Why is Ne4 considered as an inaccuracy whereas it is one of very few moves which saves d3 pawn? [FEN "r2q1rk1/1p3ppp/p4n2/2Pp4/1Pn5/P1Bp3P/3N2P1/R2QN2K b - - 4 21"]

With Black to move Ne4 is not even in top 5 moves and engine says its an inaccuracy. I know it considers fastest winning moves and positional moves too but Ne4 should be a move not an inaccuracy. Ne4 is also a forcing move with many threats.

Calling it an "inaccuracy" is nothing more than the engine saying that it evaluates the position after one move to be a certain amount better than after another move. It doesn't necessarily mean a move is "bad".
Both d-pawns cannot be kept no matter what Black does. After 1...Ne4, if White plays Nxe4, the recapture will leave the c4 knight without a defender, and it doesn't have a lot of places to go. White can win the pawn on e4 and attack that knight. And the dark squares around the Black king are just a bit weak. Black is still winning though.
If instead Black plays ...d4, this forces some trades. Simplifying the position seems like a good idea for Black, since they are winning. Overall Stockfish likes this option better.
Here's a comparison showing what the next few moves might look like for each option:
[FEN "r2q1rk1/1p3ppp/p4n2/2Pp4/1Pn5/P1Bp3P/3N2P1/R2QN2K b - - 4 21"]

1...Ne4 (1...d4 2.Nxc4 dxc3 3.Qxd3 Qxd3 4.Nxd3 ) 2.Nxe4 dxe4 3.Qg4 g6 4.Qxe4 *


Is there any good app for learning openings? My great fail is that I cannot learn opening or initial play.

Normally I only play when I can connect to my mobile app (Chess Free on iOS), and play at a very low level (adjusted as a single bar), and repeat that level until I have some domain of it. Unlike a human player or a friend, that sort of games cannot teach me which are the errors I am repeating consistently (some adaptive app?).

I've tried puzzles, but they are so artificial, I can't learn how to start with them.

I normally can defeat some people in apps such as chess.com, but very fast I reach a level superior than my real one, when I do not defeat anybody, and I don't get how to improve. After that the app download me again into trivial opponents, and the same repeats over and over.

So I don't increase my level, and I've been stuck in that from years, without any advance when facing real players.

Which I would like is to freeze the difficult level, and play let's say 100 times with players at my very exact, and me being the person to decide when it is time to move onto better players, let's say by raising 50 points only?.

Or equivalently, is there some app playing with strong focus on a specific selectable opening, let's say for example, the Dutch defense, and the game could go in turn of such opening? Making me able to play 100 times an specific opening, before increasing the level of such opening and/or before changing such opening?

In terms of apps, other than the good suggestions made so far, I definitely recommend most of "Chess King" apps, and specifically for openings:

Chess Opening Lab (1400-2000)
Chess Opening Blunders

These apps have a theory section, where various types of openings are discussed (closed, open, etc) and a practice section where you get to solve small problems specific to each opening (which you will be able to choose from).

On another note, from your description I gather your difficulties may not be necessarily opening related, but a tad more fundamental. So what you can always consider, specially at a beginner's level, is to learn basic principles about opening up the game, and not necessarily memorizing specific known opening lines. What this entails usually can be roughly summarized with the following points:

Deciding on your own style of play: open positions (e.g., 1.e4), closed position (such as 1.d4, more positional style) or the various other semi-open/closed ones.
Piece development: whatever strategy you have in mind, you first need units to execute it with, so prioritize piece development at the beginning, get out the minor pieces, occupy the centre, ...
King safety: the cliche is that you should always castle as early as possible, which is not a bad advice, but in general what matters is that you consider your king safety, and not naively undermine its importance.
Create useful space: Big part of development phase is to occupy parts of the board (often the centre) that are most accessible to your pieces (specially the minor pieces). For example, if you ignore occupying the centre of the board with your central pawns, you will have a lot of difficulties to establish centralized knights. This is often a very difficult aspect of the opening phase, as it is non-trivial and different for each opening. But think simple, you want to have active knights and bishops, so always ask yourself during your play: what structure do I need in order to post my knight here or there, or in order to have this or that diagonal open for my bishop.
Improve piece coordination: Your pieces (specially minor ones at the start) need to speak to each other, and opening theories in short provide optimized recipes to this end while refuting/limiting your opponent's play (but this is another discussion). Meaning, you have to think in terms of your collective pieces if you want to execute some plan or strategy. Amateur players tend to just opt for small tactical plans that they execute with 1 or 2 pieces: e.g., a queen and a bishop, a knight and a bishop (e.g., a bishop of f4 and a knight on b5, a typical attack on c7). Such small size attacks are often easy to parry once spotted, so try to involve as many pieces as you can for your attacks, this will make it harder and harder for your opponent to hold off. You may ask: but so when are the aforementioned "small" types of attacks useful: well, think about them in this way: on the one hand, these are small maneuvers that allow you to potentially perturb your opponent's desired setup and on the other hand, they can be seen as forceful means of rerouting your pieces to better posts. Forceful here suggests that the rerouting is without loss of tempo.
On the more practical side of things, and more related to the first point on style, you have to give different structures sufficient trials until you fully understand an opening to its nitty gritty details, details that may only at a higher level become relevant, but the good thing is the better you understand a line, the easier it will be for you to adapt if your opponent tries to refute something or deviate abruptly.
So pick up a theme of a opening you like, and play it as much as you can until you master it, then try something else, and the same routine again. This way, very soon you will have a rough idea of what to play vs many different openings, e.g. you will have a basic system vs e4, d4, and ... Again there's no recipe for what I referred to as "your basic system", because what it really means is that you will know in what terms to assess different openings and on your own out of the principles you pick up along the way, you will naturally come up with good responses.
Let me give two basic examples: Catalan (c4, d4, g3) players really like their bishops, hence the double fianchetto that often results from this line (idea being to preserve the bishops and reduce opponent choices of exchanging them), but to actually know how to leverage the two bishops takes a lot of experience and positional understanding in order to know e.g., how and when to break the centre, do I play Rc1 before c4, do I take back with knight or pawn on d4 if they take ..., and a great deal of tact, as otherwise a good opponent will easily find ways to force trade of bishops. Another opening like the Dutch: primary emphasis of the Dutch is to control the light squares on d5, e4 and the latter without having to play d5, so you preserve the possibility of playing d6 if you so desire, or if the position demands for it. With this in mind, white wants to counter these very reasons, and regain better grip over central d5,e4 squares, so first thing white annoyingly and smartly does is to give up the dark square bishop for the strong knight on f6 (which is a good re-enforcer of d5,e4 squares), e.g., 1.d4 f5 2.c4 Nf6 3.Nc3 e6 4.Bg5 Be7 5.Bxf6...
Pawn structure: its importance cannot be emphasized enough: pawn moves are the most committal moves in chess, mainly because pawns move irreversibly. This means that you need to make sure to what pawn structure you want to commit and not naively reduce your choices of expansion or defense. That's why the English opening is so powerful: it's one way of being conservative about your pawn structure, in order to have more options in reaction to what your opponent goes for. Other example, in sharp Sicilian positions, an experienced player on the black side knows not to impulsively move either the h,g and f pawns impulsively to fend off white's push, instead you have to wait until you really have to play h6,h5, g6 and so on (these are very tempting defensive moves when white is coming at you with all they have, which is the case in sharp Sicilian lines). The sooner you commit, say to g6, the earlier you've created an unamenable target weakness for your opponent to aim for. To showcase, here's a beautiful game by Kasparov (black) vs Adams:

[Title "Michael Adams vs Garry Kasparov - 2005"]
[fen "rnbqkbnr/pppppppp/8/8/8/8/PPPPPPPP/RNBQKBNR w KQkq - 0 1"]

1.e4 c5 2.Nf3 d6 3.d4 cxd4 4.Nxd4 Nf6 5.Nc3 a6 6.Be3 e6 7.Be2 Qc7 8.Qd2 b5 9.a3 Bb7 10.f3 Nc6 11.O-O-O b4 12.axb4 Nxb4 13.g4 Be7 14.g5 Nd7 15.h4 Nc5 16.Kb1 Rb8 17.h5 O-O 18.g6 Bf6 19.Rdg1 Ba8 20.Bg5 Be5 21.gxh7+ Kxh7 22.Nb3 Nxc2 23.Nxc5 Na3+ 24.Ka2 Qxc5 25.Na4 Nc2 26.Kb1 Qa3 0-1

Notice Kasparov's king-side pawns until the end ;)

Anyways, the list goes on of course and by no means should you take the above points as complete, but hopefully they do give you some pointers and I have to stop at some point :)
But what is important for you to take away, is the ways you can think about the opening phase without ever having to sit down and memorise lines, instead, from now on whenever you see a new opening being played, try to look at it with the above points in mind.


Is it better to take the knight in this position? This position is from a game I played.

I played Bxa1. I'm wondering if instead of Bxa1 I played Bxe5 then he might have played fxe5 then I play Bd3+. Is that a better continuation?

I didn't like his pawn on e5 threatening my knight and wasn't able to find a way to get anything out of the position beside his rook, so i decided to play the simpler move, Bxa1

In the initial diagram position, Black is already so much material ahead that either 1...Bxa1 or 1...Bxe5 keeps an overwhelming advantage. But 1...Bxa1 is the most straightforward, and in any case White need not allow 2...Bd3+ after 1...Bxe5 2.Nxe5. Black can first kick the knight with 1...b5 before following with 2...Bxe5 to get the ...Bd3+ idea in; that also keeps a huge plus for Black, but still the simple 1...Bxa1 is cleanest.

[Event "?"]
[Site "?"]
[Date "????.??.??"]
[Round "?"]
[White "?"]
[Black "?"]
[Result "*"]
[FEN "3r1rk1/pp2npp1/4pn2/4Nb1p/2Nb1P2/1P4PP/P3K1B1/R4R2 b - - 0 1"]

1...Bxa1
    ( 1...Bxe5 $6 {Black starts out ahead so much material that this is
    perfectly fine, but it is not best, and sloppy if nothing else.} 2.
    Nxe5 {Covering d3, so Black cannot pick up the additional exchange via
    ...Bd3+.}
        ( 2.fxe5 Bd3+ 3.Ke1 Nd7 {Black is winning handily, but won't be up
        a whole rook and pawn immediately as in the main line.} 4.Bxb7
        Bxc4 5.bxc4 Nxe5 )
    )
    ( 1...b5 {An attempt to improve on the 1...Bxe5 line, but to no avail,
    and still not as good as just snapping off the rook immediately.} 2.
    Ne3 Bxe5 {Black's first move has deprived White of the knight
    recapture, but we end up in much the same position as after 1...Bxe5
    2.fxe5 Bd3+ 3.Ke1 anyway.} 3.fxe5 Bd3+ 4.Ke1 Nd7 5.Rf2 Nxe5 )
2.Rxa1
    {Black is simply up a rook and pawn with an easily winning position.}
*


Chess.com's daily problem-Why doesn't 1...Nf8 win the Nh7? Shouldn't 1...Nf8 win here too? Why not?

[FEN "r2qk2r/pp1nnp1N/4p1pQ/3pP3/4b1PP/P1B5/1PP1B3/R3KR2 b Qq - 0 1"]

1...Nf8??

Frankly, you overlooked a major detail...Nf6+ in reply is mate. It is important to notice your "opponent's" moves too.

 [FEN "r2qk2r/pp1nnp1N/4p1pQ/3pP3/4b1PP/P1B5/1PP1B3/R3KR2 b Qq - 0 1"]

 1... Nf8 $4 (1... Ng8! 2. Qg7 (2. Nf6+ Qxf6 $1) 2... Qxh4+ 3. Kd2 Qxh7) 2. Nf6#


The King's ability to promote a piece If the King makes it to the eighth rank and then back to the first rank, can he promote a piece like a pawn can when it reaches the eighth rank?

No. The whole point of the game, the way you win, is by checkmating the opponent's king. If your opponent could exchange the king for another piece then you would no longer be able to win.
In any case, all the pieces except the pawns can move backwards. Without promotion any pawn which reached the 8th rank and couldn't promote would no longer be able to move. That doesn't apply to all the other pieces.
FIDE, the international chess federation publishes the laws of chess on their website. The first 5 articles describe the rules for general play. The articles from 6 onwards describe additional rules which apply to official competitions.


What is the piece value heuristic in atomic chess? In regular chess a queen is worth 9, rook 5, knight 3, etc. What is the equivalent heuristic in atomic chess?

The answer is, as expected, "it depends". To answer directly first, 2016 Atomic World Championship (AWC) winner, tipau, put the values as:

Pawn - 1
Knight - 1.5
Bishop - 1.5
Rook - 3
Queen - 6

As a somewhat strong player myself (two top-8 finishes in the AWC) who has extensively analysed atomic chess endgames, I would tend to agree.
The king has no value, but outside of stopping passed pawns in endgames and a few other special zugzwang compositions, it is almost useless.

Now to go deeper into the topic, do note that the piece values change during the game. General experience would give the following points to support the piece values:

In an endgame, a minor piece is only slightly more than a pawn; if one side has N pawns + 1 minor piece while the other side has N+1 pawns, the side with the minor piece has a slight advantage (which may not be enough to win, depending on the position).
In the middlegame, a minor piece is worth more than a pawn, but usually less than two pawns.
A rook is generally worth more than a minor piece, especially when there are more open files for invasion. A minor piece + pawn can compensate for a rook in the endgame though, generally forcing the side with the rook to take a draw by perpetual check.
Knights are generally better than bishops in the very early opening and endgame, but not in the middlegame.
The bishop pair is much stronger than the knight pair or a knight + bishop.
The queen's value is hard to pin down. Depending on the position, she can be worth less than B+N, or more than R+B+N+P, as seen in several common opening lines. It largely depends on the solidity of both sides' positions.
Factors like piece activity, pawn structure, passed pawns and other non-material considerations also matter in any given position.

I would therefore recommend using the following rules of thumb instead of exact point values:

B ~ N (depends)
N/B slightly > P
B+B > 2 minors
R > N/B
R ~ N/B + P
R > P+P
R < B+N
Q somewhere between B+N and R+B+N+P


How do I learn a new opening? Often times, when I find myself going through the lines of a new opening, one that I would like to start using in my games I hit the concrete wall after a couple of days of studying it.

Due to the fact that this is new to me, I simply don't understand every strategic line behind it, and since I've never played it I don't know what to expect in a real game. So my question is:

During the first stage of leaning a new opening, just memorize the different possible variations?

Or

Deep dive in the theory behind each move until you acquire a thorough comprehension of the tactical and strategical motifs?

The following suggestions will work for players in the 1600-2000 elo range. If you are above 2000, you probably already have better techniques than these. And if you are 1600 or below, tactics is arguably a lot more useful to learn.

Here's an assortment of things I used to try when I wanted to learn a opening. Note: I had access to Fritz and Chessbase and that helped.

Get a book (or a chess video) on the major ideas in the opening or variation that you are interested in.
This is fundamental. Watch it, or read it multiple times to absorb the themes.
Get hold of a bunch of games with your opening of interest. (Chessbase or Fritz makes this really easy). Sort them in different ways into smaller databases for your own reference.
Play through the games in various speeds. Click the steps fast, every few seconds, or very slow to absorb what's going on.
(Ideally, you want to focus on the games where your color of choice wins. That way you'll know the winning themes.)
I often learned by playing through games of players who were a 100-200 points above me, rather than from GM's. The reason was that my opponents would deviate from theory very early on, and I could see how players of strength comparable to me handled the positions.
Pay attention to the minor pieces and see which squares they usually occupy. Chessbase has a cool feature that plots the probability of a piece occupying each square in your opening of choice. I found that very useful.
Play through the games paying attention mainly to the pawn structure.
For me, it was usually enough to learn the first 10-12 moves and then the ideas. If you play the same opening enough, you can increase that to a few more moves.
I learned this technique from Silman's book. I'd print out a position (from the opening I was trying to get familiar with) and then stare at it and try to write down a very detailed evaluation of it. This was surprisingly difficult for me. I could come with a few basic points, and then I 'd go over someone's annotations and see that they could look much much deeper into the position. Doing this often can be quite beneficial.
I'd run my games through Fritz's analysis and watch in horror at the things both me and my opponent had missed. But I also learned not to miss those things the next time.
Keeping your own annotations is extremely useful. I'd write notes and keep adding to it as I learned more. Reading my own notes was often more helpful than reading the IM's and GM's who had much deeper knowledge.

Hope that helps.


Why 7. Bd3 in the 3 knights opening? In this line of the 3 knights opening

[fen "start"]

1. e4 e5 Nf3 Nc6 Nc3 Bc5 Nxe5 Nxe5 d4 Bd6 dxe5 Bxe5

the best continuation according both to my engines and to databases is 7. Bd3. Why? For instance, can anyone explain why that's better than 7. Be2 or 7. Bc4?

Below some of the reasons I found by myself, but I would love to have confirmation or hear more:

If the pawn on e4 moves, the bishop would attack the h7 square which might be helpful for a mating attack in case black castles king-side. 7. Be2 doesn't attack any important square
7. Bc4 would attack f7, but the bishop is undefended on c4 and might become a target
7. Bd3 gives extra protection to the e4 pawn (useful in case white needs to move the knight on c3), neither 7. Bc4 nor 7. Be2 does that

A light-squared bishop move here is in order so that white can castle soon. The choices that you mentioned are definitely the only ones that aren't dumb/lose a tempo.

Be2 is probably the worst of the reasonable choices. Its only result is to allow castling, and it kind of clogs up white's middle - potential moves like Ne2 or Qe2, which may show up at some point, are off the plate.

Bc4 and Bd3 are both solid, I think. There likely wasn't much of a difference in the engine evaluation for these moves, and depending on the tools you used to conduct this analysis, the difference may be within the margin of error for the program. Essentially, I'm not sure there is a measurable difference between these moves in terms of evaluation.

Assuming that there is an actual difference, you might also consider that engines are fairly notorious for NOT playing attacking chess. It has been argued that they focus too much on material imbalances and not enough on position/pressure/psychology. The move Bc4 "feels" scary, but the engine sees that with perfect play, it isn't much of a threat. The pressure on the e4 pawn, however, will be real with perfect play, and it moves to defend that pawn.

Essentially, Bc4 might be more practical in a game between imperfect people, but the attack it provides is not real enough to matter in a perfect game - thus Bd3 is technicallybetter.

Play whatever you're more comfortable with.


Chess engines' .dll files usable in C# projects Are there any free/paid chess engine .dll files that could be used in a C# project as a reference?

Take a look at the C# port of Stockfish by bpfliegel. To my knowledge it is complete (was able to compile and run it) and even though it has not been updated in 11 months at the time of this post it is certainly much stronger than the other engines listed. When I tested its perft function it on my machine it was only a factor of 1.5 slower than the original C++ implementation.


It's true that a middle game plan is to push the rest of central pawns? A master 2250 said to me that i should put my pieces so all
my central pawns to be pushed.

For example if I have e4 d5 with white, a valid plan is advancing c4 and f4. Or with black if I have for example d6, e5, I should prepare f5, d5, and c5. Is this a plan for general middle game positions? Advancing e4,d4,c4,f4 for white and e5,d5,c5,f5?(Order doesn't matter).

This might be a valid plan, if you opponent doesn't fight for the centre at all. But in almost all games such a plan is either impossible or carries the risk of overextending.

It is true that pawn levers are important. Such a pawn lever might be the advance f4-f5 or c4-c5. But usually you only play a pawn lever at the side of the board where you are stronger and ready to exploit the opening of the position. Not just everywhere …

In my view it would be much more correct to state the building of an ideal pawn centre as a standard plan. But the "ideal pawn centre" consists only out of the e and d-pawn, both advanced two squares. And even the building of this modest 2-pawn centre is usually fought tooth and nail by your opponent.

[FEN ""]
[Event "Nanjing Pearl Spring Tournament"]
[Site "Nanjing CHN"]
[Date "2010.10.24"]
[EventDate "2010.10.20"]
[Round "5"]
[Result "1-0"]
[White "Magnus Carlsen"]
[Black "Veselin Topalov"]
[ECO "C78"]
[WhiteElo "2826"]
[BlackElo "2805"]
[PlyCount "63"]

1.e4 e5 2.Nf3 Nc6 3.Bb5 a6 4.Ba4 Nf6 5.O-O Be7 6.d3 b5 7.Bb3
d6 8.a4 Rb8 9.axb5 axb5 10.Nbd2 O-O 11.Re1 Bd7 12.c3 Ra8
13.Rxa8 Qxa8 14.d4 h6 15.Nf1 Re8 16.Ng3 Qc8 17.Nh4 Bf8 18.Ng6
Na5 19.Nxf8 Rxf8 20.Bc2 Re8 21.f4 Bg4 22.Qd3 exf4 23.Bxf4 Nc4
24.Bc1 c5 25.Rf1 cxd4 26.cxd4 Qd8 27.h3 Be6 28.b3 Qa5 29.Kh2
Nh7 30.e5 g6 31.d5 Nxe5 32.dxe6 1-0

Take this brilliant game as an example: On move 14 Carlsen creates the "ideal pawn centre", it persists until move 30, where is proves its power by advancing and initiating a deadly attack. There is even a pawn lever thrown in at move 14, which opens up the f-line for the rook. But Carlsen didn't try to just move his c,d,e and f-pawn forward. He created the ideal pawn centre, which controls a lot of squares and can at times advance with deadly effect. He used a pawn lever to open up lines for the attack. Every move had a purpose.


As a beginner, how do I learn to win in "won" positions? I'm fairly new to chess (~3 months) and I have almost entirely been playing on chess.com where my rating sits somewhere between 1000 and 1100. Recently, I decided to sign up for lichess.org, where I was placed at ~1650 as I haven't played many games yet, and unsurprisingly I lose quite often.
But facing higher rated players made me realise I don't know how to win a game of chess.
On chess.com, the people I face will almost always trade pieces if offered, so if I have a material advantage it is very easy to trade off all other pieces then staircase checkmate and win. Facing higher rated players on lichess made me realise that if they don't cooperate like this I have no idea what to do. I know I sound pretty stupid here but somehow I have just never had a game like this before.
In this game, by the end Stockfish says it was -3.1 (I played the black pieces) when my opponent lost on time, but if they didn't, I have no idea how I was going to win if they didn't at least trade queens.
[Event "Rated Rapid game"]
[FEN ""]
[StartFlipped "1"]
[Date "2020.12.13"]
[White ""]
[Black "Me"]
[Result "0-1"]
[UTCDate "2020.12.13"]
[UTCTime "08:02:31"]
[WhiteElo "1655"]
[BlackElo "1645"]
[WhiteRatingDiff "-6"]
[BlackRatingDiff "+10"]
[Variant "Standard"]
[TimeControl "600+5"]
[ECO "C48"]
[Opening "Four Knights Game: Spanish Variation, Classical Variation"]
[Termination "Time forfeit"]

1. e4 e5 2. Nf3 Nc6 3. Nc3 Nf6 4. Bb5 Bc5 5. O-O a6 6. Ba4 b5 7. Bb3 O-O 8. a3 Bb7 9. Re1 Ng4 10. Rf1 Nd4 11. Ba2 Nxf3+ 12. Qxf3 Qh4 13. h3 Nf6 14. b4 Bd4 15. Bb2 Bxe4 16. Qe2 Bxc3 17. Bxc3 Qg5 18. f3 Bxc2 19. d4 Qg6 20. dxe5 Bd3 21. Qb2 Bxf1 22. Rxf1 Ne8 23. f4 Qb6+ 24. Bd4 Qc6 25. Rc1 Qh6 26. Be3 d6 27. exd6 Nxd6 28. Rxc7 Rac8 29. Ra7 Ra8 30. Qf2 Rxa7 31. Bxa7 Qf6 32. Bd4 Qh6 33. f5 Qc1+ 34. Kh2 Nc4 0-1

So I'm not really looking for somebody to tell me the best continuation of this game so I could win, but is this a problem with playing too passively? As in, "I should be actively attacking the king more" is my assumption, but I'm unsure how to learn about how to do that. I came across Vukovic's Art of Attack in Chess when searching online but according to the /r/chess wiki that book is for 1800-2000 rated players. So my question is what should I be focusing on to be able to win in these positions?

There are two key things you need to do.
The first is to know how to win a won endgame. You do that by studying endgames. That will do two important things for you. Apart from teaching you how to win a won endgame, it will also teach you to recognise which endgame positions are won, and which are drawn, despite your material advantage. That way when you are in a winning middlegame you know what kind of endgame you are aiming for.
The second really important thing to do is to keep on fighting. The aim is not to get a winning middlegame position, it is to win the game. To that end a winning middlegame position is just one stop on the way to your real desired destination.
If you are driving to visit friends or family and you stop two thirds of the way there for petrol (or gas if you live in the US) you don't stop because you think you have arrived. You carry on after the stop, in just the same way as you did before the stop, except that you are no longer worried that you are going to run out of fuel (or not win the game).
This tendency to sit back once you have a theoretically winning position is something which affects all players. You have to fight it by trying even harder to not let your opponent back into the game and to win it yourself. Perhaps one good way of doing this is by starting each think about your next move by asking yourself "Why did my opponent do that? What are they trying to do? How can I stop them?"


PGN viewer / replayer for Atomic Chess I'm looking for a PGN viewer that works with the Atomic chess variant, in that captures removes adjacent pieces. However, PGN viewers I've found so far have little to no support for chess variants, less to Atomic chess specifically. It doesn't matter if it works online as a web service or a separate program; what options are there?

Winboard/XBoard should do the job.

http://www.tim-mann.org/xboard.html


Why do players play this move (bishop to b6) in bullet chess? I've often seen (on lichess, I play only bullet, at ratings 1800ish) black play the f8 bishop to c5, and then if white challenges it by playing their c1 bishop to e3, black retreats their bishop from c5 to b6, and then if white captures, black recaptures with the a7 pawn.

rnbqkbnr/pppp1ppp/8/8/8/8/PPP1PPPP/RNBQKBNR b KQkq - 0 1

1. Bc5  Be3 2. Bb6 Bxb6 3. axb6

Why is this a good move? I've see it CONSTANTLY in a variety of openings, and I myself never play this way.

It seems a bad move for black to me because

a) you lose a tempo.

b) you double your pawns.

c) yes, you do get an open file for your rook, but ... so what, quite frankly? It's a bullet game. You are probably not going to have the time to think of some ingenious rook lift in the middle of the game. It just seems too risky to utilize that a-flank with the rook in a bullet game, at least for the players at my level. Indeed, I can confirm that I can't recall a single game where black utilized the strategy above and actually got something worthwhile out of it. The rook never made an impact on the a-file in a single bullet game that I've played where black played above strategy.

So why do players do this?

Actually, ..Bb6 is a sound move not just in Blitz. The Italian and Scotch game are filled with it. There are plenty of reasons why you would make it:

After 1.e4 e5 2.Nf3 Nc6 3.d4 exd4 4.Nxd4 Bc5 5.Be3 White is threatening to win a piece, so Black can retreat to b6 and prevent his bishop from hanging.
Let's assume a central formation like e4+d3 vs e5+d6, with a Black bishop on c5 and a White bishop on e3. It is good for Black to retreat to b6 (even if ...Bxe3 or even just leaving it on c5 could sometimes be considered) in order to trade them on that square and open the "a" file. In your post you give a lot of importance to the fact that this doubles pawns and very little to the opening of the file. But I would say that, specially in Blitz, the file is way more important! White will have to worry about the a8 rook for the entire game.
Finally, Black could have retreated to b6 (or a7) to prevent a trade and keep a powerful bishop on the a7-g1 diagonal.


How to assess chess game composition? Most chess literature offer sets of moves based on themes, but do not offer a method of accessing your performance in composing sets of moves relative to the flow of the game itself.

What would be the best way to segment sets of moves, and then assess the effectiveness of their composition relative to the board's state?

I would try breaking your games down by sub-goals and examine the moves leading up to achieving that sub-goal which gives you an easy metric on how well the set of moves performed.  Of course, the harder part is to assess your sub-goals.  Did you have the right overall plan?  Did your sub-goals improve your position?  I'm not sure if breaking your evaluation down to the "set of moves" level will ultimately be useful.

For instance, you can set a sub-goal of controlling the c-file so the set of moves that contribute to doubling the rooks on the c-file evaluate as "good".  However, if your opponent is invested in an attack on the king-side, your sub-goal might be faulty.

Take a look at some middlegame books, games collections, and/or tournament books.  Try something like IM Jeremy Silman's "How To Reassess Your Chess" and/or GM Bronstein's annotations of the Zurich 1953 tournament.

The former will give you some ways to approach thinking about your position and formulating goals while the latter will delve into the thought process behind the moves of real games of grandmasters.


A chess player's weakness assessed How can I discover my weaknesses in chess and order them from biggest to smallest? I'm guessing a strong GM could analyze a couple of my games and do this for me. But I'm not sure it's worth the economic investment. Is there another way for me to do this?

Made two self-assessment book recommendations to a related question (How to automatically evaluate a player's performance in a game?). Igor Khmelnitsky's Chess Rating Exam is pretty thorough at evaluating every aspect of your game.

BTW, really like that you are approaching this in a analyzing/organizing your "biggest weaknesses" manner rather than embarking on the fairly commonplace it must be the openings, so I need to study openings knee-jerk/inefficient study plan.


Minimal number of moves before castling in Chess960 As you know, in the initial position Chess960 the king lies between the two rooks. Here are the rules for castling.

For a starting position P, let n(P) be the minimal number of moves that White needs to legally castle kingside. How many positions are there such that n(P)=1?, n(P)=2, and so on?

There are cases where we can castle n the first move, namely when the King on f1 and the rook on g1. There are also other extreme cases with the king on b1 and the rook on c1, so then we have to make space.
Maybe some engines can solve this question.

The three first steps:
There are 90 positions where n(P)=1
For White to be able to castle short at once, he needs to have Kf1, Rg1 in the initial position. Then there are 5 possible spots from the second rook, 3 for one bishop and 2 for the other one, and finally 3 remaining spots for the queen. The knights go to the last two spots.
There are 64 positions where n(P)=2
36 of them with Kf1, Ng1, Rh1: White can play 1.Nf3 or 1.Nh3 and 2.0-0
28 of them with Rg1, Nf1, Ke1: White can play 1.Ng3 or 1.Ne3 and 2.0-0
There are 242 positions where n(P)=3
please double-check this part
Here are the different configurations and the number of relevant positions:
xxxxxQKR 18
xxxxxBKR 36
xxxxxRKR 18
xxxxxKQR 18
xxxxxKBR 24
xxxxKNNR 8
xxxKNNRx 6
xxxKNRNx 6
xxxKRNNx 6
xxKRxNNx 4
RKRxBNNx 2
EDIT: Now I have a doubt for these two cases. Is castling allowed in Chess960 in spite of a piece being "on the way" on e1 ?
xxxxKBRx 24
xxxxKQRx 18
xxxxKRBx 36
xxxxKRQx 18
Total:242
Once we reach n(P)=4, we cannot ignore Black's play anymore: for instance, QNRNKBBR looks like it should have n=5, but actually it has n=4 because of the sequence 1.f4 b5 2.Bxa7 Qxg2 3.Bxg2 Nc6 4.0-0. Counting by hand becomes too fastidious and hazardous: a software program is needed.

On the other hand, after clarification by the OP, I believe 7 to be the maximum value of the function P->n(P).
If Black wasn't allowed to "help" we could build only 2 positions with n(P)=9; Here is one, the other is similar with RKBBNNQR on the first rank.
[FEN "rkqnnbbr/pppppppp/8/8/8/8/PPPPPPPP/RKQNNBBR w - - 0 1"]

In a series problem where White plays alone he would need 9 moves in order to castle. But since Black moves are taken into account, White actually can castle on move 7 from that diagram if the game goes something like 1.b3 d5 2.Qa3 Qe6 3.Nb2 Qxe2 4.Nd3 Qxf2 5.Bxf2 Nc6 6.Be2 0-0-0 7.0-0.


Nimzowitsch specific game with Nf6-g8 Is there any way to search for games by a player where the move "x...Ng8" took place?

I'm looking for a specific game.

And no, it's not Saemisch - Nimzowitsch, Berlin 1928.

If you have your database in clear text format such as pgn, and if you are satisfied with any knight move to g8, you could just search for the string "Ng8" (and potentially "Nfg8", "Nhg8" and "Neg8") in the pgn.

This does not help if you want to filter for Nf6g8 only, unless there is a way to save the pgn with long algebraic notation. Also you would find both black and white knights moving to g8 (probably a lot more black than white moves though).


How is the 2016 Zurich Chess Challenge "new classical" format different from rapid chess? For the upcoming (2016) Zurich Chess Challenge, a new time control will be put in place. According to chess24,

  Six players including former World Champions Vladimir Kramnik and Viswanathan Anand compete in a "new classical" and blitz round-robin event with a novel format and time control.

which is later clarified as

  A five round-robin tournament in which players receive 40 minutes plus 10 seconds per move for the entire game.

How is this different from a standard rapid time control? And will this section of the tournament affect the players' classical ELO rating?

This is not different from rapid chess and will be rated only for the rapid Elo.

The name "new classical" is part of a push to shorten the classical time controls. Originally the idea was to have a time control with around 60 min per game, but in the end they decided to shorten it a little to make the games eligible for the rapid rating at least.


How should I play wiith White and Black in the Sicilian Dragon? How should I play with White and Black in the Sicilian Dragon?

[FEN ""]
1. e4 c5 2. Nf3 d6 3. d4 cxd4 4. Nxd4 Nf6 5. Nc3 g6 6. Be3 Bg7

My personal opinion:
If you are really annoyed of your opponents opening preparation of early dragon then just avoid it in the beginning. There is a friend of mine who crammed the dragon at length. I was extremely annoyed. To avoid the dragon I started to play Morra's Gambit. Morra's Gambit is quite effective. It can take your opponent out of the opening. You can try Morra Gambit if you are an attacking player otherwise do not go for it. You need to play quite sharp in Morra's Gambit. If you lose your tempo then the Gambit will go in vain and the opponent will get a clear advantage of 1 pawn.

Short answer:

If you want to deal with the position after 6...Bg7 then you will have to learn the theory. The main options are  7.Bc4,Be2,f4,f3.  Other option are 7.Bb5+, even moves like 7.a3,a4  or  7.h3,h4 are playable. 7.h4 is quite attacking and 8.h5 can be sacrificed for a open file. 7.g3 is also playable but it seems like a dull move because Bg2 won't be very effective because black's Night can soon jump at g4.

In 7.Be2 or Bc4 line sometimes after some moves there is an option of retreating the bishop on f1.

There is so much theory that a full fledged book can be written.

In some lines you may go for opposite castling but you will loose your small opening advantage. It will be still playable because the game will become highly tactical and attacking for both the sides. If you are good in tactics you can try this.

If you do not like very much Black's dark bishop on g7 then you can double your bishop with Queen(7.Qd2) and force Black to trade the bishops. Again doing this will give up your opening advantage.

If you are not playing at GM level then small opening advantage doesn't matter. Infact the whole opening doesn't matter.

The real answer to your question is read a book of dragon variation and use latest stockfish engine to analyse different lines :-)


How long to get a 200 rating point increase from serious chess study alone according to this academic paper? In the academic journal article "The Role of Deliberate Practice in Chess Expertise" from APPLIED COGNITIVE PSYCHOLOGY Appl. Cognit. Psychol. 19: 151– 165 (2005)

At the top of page 162, the authors state that

  "...each log unit of serious study alone yields about 200 rating
  points compared to 33 rating points for log tournament play. Hence,
  players ought to devote the majority of their time to that activity."

I have gone over this academic paper several times, but I cannot decipher what "each log unit" represents. What time span is a "log unit" in this context where studying chess alone gave the chess players in this academic paper 200 ratings points vs 33 ratings points from playing in tournaments? Is it 6 months, 10 months, a year?

The first paragraph of the RESULTS section on p. 155 says

  We applied log-10 transformations to three variables (cumulative study alone, cumulative tournament play, and chess book library size) prior to correlation and regression analyses.

The log-10 (logarithm base 10) of a number is what power you have to raise 10 to in order to produce that number; e.g. log 100 = 2, log 1000 = 3, etc.

So the sentence

  each log unit of serious study alone yields about 200 rating points

means that, all other things being equal, if player A studies ten times as long as player B, his rating will be about 200 points higher. (Another student who studies a hundred times as long as player B will have a rating of about 200 points higher than player A.) So there is no constant time span per 200-point gain; the required time to gain a particular amount of rating improvement gets larger and larger as you improve. (Another way to put this is that chess study produces diminishing returns.)

(In a sense, the Elo rating system is logarithmic as well, so you could claim that the relationship between study time and playing skill is actually linear. But since everybody measures playing skill by Elo rating, that's not so productive.)


Deviating from standard Danish gambit I like to play the Danish gambit opening. Frequently, black won't take the last pawn to complete the standard opening, but instead plays the knight as shown below. I'll generally play Queen to b3 or f3. But then black plays Knight to a5 or e5, respectively, which results in losing the c4 bishop. Is there a nice way for white to respond to Nc6?

[fen "r1bqkbnr/pppp1ppp/2n5/8/2B1P3/2p5/PP3PPP/RNBQK1NR w KQkq - 0 1"]

Just develop your pieces. 5.Nf3 makes sense, preparing to castle. 5.Nxc3 is also reasonable; if Black refuses to play ... cxb2, you'll probably have to play Nxc3 at some point anyway. These are the only two regularly played moves in the given position.


When should black make the cxd4 move in French? [FEN ""]
1. e4 e6 2. d4 d5

Following the structures with black pawn on c5, there is a tension in the center. When does black usually decide to take the d4 pawn, what is usually the trigger?

Generally speaking, resolving tension helps the defender. White is the defender as far as the d4 square is concerned so Black should not aim to play c5xd4 unless he gains some follow-up advantage by doing so. One such advantage might be access to the b4 square for a knight or bishop after the reply c3xd4.


Polyglot opening book: getting incorrect moves I am in the process of adding an opening book to my C++ engine and I hit a problem. Here is what I have:

The Perfect2021.bin opening book that I would like to use.
The function that creates the polyglot hash for the board. I tested this with many boards, and it is correct.

Now I would like to retrieve and for now only print all the moves my engine can make in a position, according to the book. I tried it with the following method:
move opening_book::getBookMove(const chessboard& board, const game_information& info) {
        uint64 boardKey = polyKeyFromBoard(board, info); //get key for board
        std::cout << "Finding moves for board key: " << std::hex << boardKey << std::dec << std::endl;
        unsigned short moveKey;
        //list moves from the book
        for(polyglot_book_entry* entry = entries; entry < entries + entriesNumber; entry++) {
            //apparently I need to swap bits for these
            if(boardKey == swap_uint64(entry->boardKey)) { //found the board in the book
                moveKey = swap_uint16(entry->move);
                unsigned short fromFile = (moveKey>>6)&7, fromRank = (moveKey>>9)&7,
                               toFile = (moveKey>>0)&7, toRank = (moveKey>>3)&7;
                unsigned int fromSquare = (8 * fromRank) + fromFile,
                             toSquare = (8 * toRank) + toFile;
                std::cout << "Move found: " << createSquareName(fromSquare) << createSquareName(toSquare) << std::endl;
            }
        }
        return move(); //not returning actual move right now
    }

But when I for example make my engine play black and I open the game on white with the move e2e4 then the following is printed upon the engine checking the opening book:
Finding moves for board key: 823c9b50fd114196
Move found: c2c4
Move found: e2e4
Move found: c2c3
Move found: e2e3

The board key is correct. It is one of the test cases on this site. However, as you can see the moves that are found seem to be for white.
Can someone please help me out? Thanks.

I have found the problem: my board representation was different and while my ranks are also from 0-7, but they are counted from the black side, while in the polyglot encoding, they are counted from the white side (which makes sense).
So I had to invert my ranks like so:
unsigned short fromFile = (moveKey>>6)&7,
                          fromRank = 7 - ((moveKey>>9)&7),
                          toFile = (moveKey>>0)&7,
                          toRank = 7 - ((moveKey>>3)&7);

Files remain unchanged. I am now getting reasonable output:
Finding moves for board key: 823c9b50fd114196
Move found: c7c5
Move found: e7e5
Move found: c7c6
Move found: e7e6


What are some good chess calendars? I am having a hard time keeping up with recent tournaments. Are there any good online calendars?

Here's a link to the fide calendar: https://www.fide.com/calendar

Also, this link includes the tournaments which will feature some of the top super GMs (e.g., the Olympiad, Sinquefield Cup, Altibox Norway Chess): https://chess24.com/en/read/news/2020-chess-calendar


What openings are closed and defensive? Which openings would be regarded as leading to a closed position and being defensive?  Specifically, openings that would be drawish, even against stronger players, but there is still always a possibility of squeezing out a win if played carefully and the opponent goes wrong.

The openings which are considered more drawish are usually openings where you have no central tension and symmetric pawn structure, something like the exchange French/Slav.  It's asymmetry and tension that gives room for complications.  I can't think of many huddled, solid defensive lines where the goal is just to be closed and impenetrable, though you could argue a tamely played and unambitious Stonewall, Colle, or London could fit the bill.  Still, by playing this way, you are creating an imbalance in space and activity which isn't in your favor.  Not recommended.


Vienna Game: Struggling to find a good response to 2...Nc6 I am starting to pick up the Vienna Game but I'm struggling to find a satisfactory response to 2...Nc6, the Max Lange Defense. The main moves according to theory here are 3. Nf3, 3. Bc4, 3. f4, 3. g3.

Nf3 just transposes into Four Knights territory, and I do not want to play the Four Knights because it just looks really symmetric and boring to me.

Bc4 is what I want to make work, but it seems to me like Black can equalize too easily if they know a move or two. After 3...Nf6 4. d3 Na5! you lose the bishop pair, and according to Lichess this doesn't have a great winrate for White. Any move other than 4. d3 results in 4...Nxe4 5. Nxe4 d5!

f4 is essentially a delayed King's Gambit due to the lack of a knight on f6, so it seems kind of risky to me.

I'm not familiar with the positional ideas behind 3. g3. As a beginner, I guess I'm looking for something more aggressive (but sound)?

I picked up the Vienna Gambit a year ago and ran into the same quandary over 2. ... Nc6, I generally agree with your assessment of each candidate move, and I don't see that you have much real choice apart from those four.  Taking into account that your preferred line is the Vienna Gambit, and that you'd like to be able to deal with alternatives to 2. ... Nf6 in a similar spirit:

Nf3 definitely isn't what you want!  If you were comfortable/happy with 3. Nf3, you'd play 2. Nf3 instead of the Vienna.

Bc4 is a pity.  Before switching to the Vienna Gambit, I was originally drawn to the 3. Bc4 Vienna because of the fairly reliable prospect of getting 5. f4 without gambitting the pawn, but indeed, Black can and should spoil your fun by trading off your bishop with Na5 as soon as you've played d3.  The resulting position is playable, but as with the Four Knights, generally not much fun for the sort of player who'd opt for the Vienna to begin with.  In practice, a lot of players unfamiliar with the Vienna will instead give you 3. ... Bc5 4. Qg4!, so this could be a workable choice in club-level blitz, but "hope chess" should never be the basis of a repertoire decision.

g3 is a much slower and less forceful way to achieve f2-f4 and results in positions of a very different character from developing the Bf1 to c4 or b5.  Once again, playable, but not in the spirit of the Vienna Gambit.

My recommendation is to take a closer look at 1. e4 e5 2. Nc3 Nc6 3. f4.  Granted that it's a transposition to the King's Gambit where Black can take the pawn freely without fear of 4. e5 ideas found in the Vienna Gambit, but I think you'll find that the character is about as close as you're going to get to the Vienna Gambit without risking the boring Na5 lines of 3. Bc4, and in chess we don't have the luxury of always getting exactly the flavor of game we'd like.  If your concern is that it's riskier than you prefer, consider the following:

Going back to the Vienna Gambit proper, remember that Black can accept the gambit and walk into 4. e5.  It's a bad decision, but it's not an instant loss, it's hardly risk-free for White, and it will require some technique from you to fully take advantage of Black's misstep.  By playing the Vienna Gambit, you sign on to occasionally play the crazy King's Gambit-ish positions that result from Black accepting the gambit.  In this sense the 2. ... Nc6 3. f4 lines are similar in character to the Vienna Gambit.
With Nc3 and Nc6 having been played, a quick d7-d5 is ruled out.  You're playing a King's Gambit where Black doesn't have access to the Falkbeer Countergambit 2. ... d5 or the Abbazia Defense 2. ... exf4 3. Nf3 d5.  Black has fewer credible replies, and can't really decline the gambit except in ways that permit you to keep your pawn on f4 and transpose into 3. Bc4 Vienna lines where Black hasn't played Na5, which should be pleasant enough for a Vienna Gambit player.
If Black does accept the gambit, presumably you're going to respond 4. Nf3; if you're happy with Vienna Gambit levels of risk but not King's Gambit levels of risk, then allowing 4. ... Qh5+ and having to move your king is probably not your cup of tea.  So now we're looking at the 3. Nf3 King's Gambit proper, except the presence of Nc3 and Nc6 limits Black's options and slightly modifies the character of the remaining choices, a small plus to the Vienna player in terms of familiarity that should decrease the risk.  You're also one move closer to being able to castle long, generally desirable both for safety and for achieving positions closer to what you would have gotten out of the Vienna Gambit main lines from 3. ... d5 4. fxe5 Nxe4.  In many cases you have a decent prospect to fight for d2-d4 and Bxf4.

There are two main issues for you to consider in the lines after 1. e4 e5 2. Nc3 Nc6 3. f4 exf4 4. Nf3.  If you can reconcile these with your tastes and aptitudes, then I think 3. f4 should be absolutely fine for you.

Just as in the King's Gambit, even if you opt for Nf3, Black may play Be7 and uncommon Bh4+ ideas that will require you to either move your king or (if you played Bc4 in advance) castle short in a tricky position where you have neither f nor g pawns and Black is bearing down on you.  The database stats are encouraging either way, but you will need to know what you're doing and you will need to be comfortable playing in some really madcap positions.
Nc3 and Nc6 aren't solely an improvement for White; the presence of Nc6 means that if Black holds the f4 pawn with 4. ... g5 (by far the most popular choice), and then pushes 5. ... g4 (popular if you play 5. d4 or 5. Bc4, all but guaranteed if you play 5. h4), now you can't simply play Ne5 and preserve some degree of sanity.  With Black's Nc6 preventing you from escaping to e5, you basically need to be prepared to sack the knight, whether that's 5. d4 g4 6. Bc4 gxf3  (or Bc4 first and then d4) in the style of the Muzio Gambit, or 5. h4 g4 6. Ng5 h6 7. Nxf7.  Just about the only alternative to sacking the knight (aside from retreating it...) is 4. ... g5 5. d4 g4 6. Ne5 Nxe5 7. dxe5 Qh4+, which to me looks considerably weaker.  Good news, both knight sacks are playable if you know what you're doing.  Bad news, most likely neither of them is perfectly to your taste if you opted for the Vienna Gambit over the King's Gambit.

In the end, no opening is going to give us exactly what we want 100% of the time.  1. e4 players get to pick their poison between the Ruy (the Berlin stifles the greatest attacking players), the Italian (3. ... Bc5 can be a slog, unless you like the Evans Gambit), the Scotch (3. ... Bc5 again...), various gambits of the d4 pawn, the King's Gambit with Black's numerous strong retorts and White's razor-thin margin for error, and the Vienna with the potential drawbacks you've noted in each major variation.  The other possible first moves for White all have their own equivalent issues.  Take your pick, either based on which troublesome lines you're most likely to meet, or based on which troublesome lines you would most prefer to never meet.  I've tried most everything listed here and found that my personal preference is the Vienna Gambit, with 3. f4 in the case of 2. ... Nc6, and while it's certainly not a choice without drawbacks, you don't have any choices that are wholly without drawbacks.  My advice is to examine the 2. ... Nc6 3. f4 lines a little more closely and decide whether potentially being forced to sacrifice a knight every now and then is preferable to your grievances with the alternative third moves.


Is playing stronger oppenents useful as a beginner? I have signed up to a chess websites and there are very few people who are as bad as I am (rating around 800), so I have to resort to playing against people who are much better (1200+) and end up beating me very quickly.

I do analyze the games to see what went wrong but I am wondering if it's even worth going up against players much better than me, since I don't get to even the end game stage.

As long as you're also playing players of your rating (and lower) along with the higher rated players it's okay. You don't want to be discouraged by losing every single game you play. Ideally you want to play people higher rated than you more than lower rated because it's like getting a free lesson - a higher rated player will be able to take advantage of your mistakes more than a lower rated player.

At a 800 rating, you'll want to focus on basics (basic opening principles, tactics, safety, thinking processes etc.) and review your games for common mistakes to pinpoint weaknesses and then eradicating them.

Of course, you'll also want to play slow time controls more than fast time controls as you want to be able to think about your moves and then be able to go back and correct your thinking. Faster games involve a lot of intuition and at your rating you won't really have a lot of it. So you'll want to develop that by playing slow time controls. Besides, you don't want to mess up games and then excuse yourself by saying that you didn't have enough time on your clock.

Also, you should begin reviewing some (master) chess games. A decent beginners book is Logical Chess by Irving Chernev. Don't review modern GM games yet as those are generally a lot more difficult to understand.


What is an example of a very difficult one-move checkmate? Usually one-move checkmate puzzles are easy. However, I am wondering if there is a relatively more difficult one-move checkmate puzzle. Here are a few thoughts:

There are many legal moves.
One or several legal moves are tempting but incorrect. Especially under time pressure, an inexperienced player tends to choose such a "wrong" move.
Finding the checkmate move requires some out-of-the-box thinking. It is a move that most players will not normally consider, expecially under time pressure.

Anyone knows a good "difficult" one-move chekmate problem?

Very difficult is relative and given enough time players of most strength should be able to find a mate in one.

I don't have a concrete example, but in my view the following features would make it more difficult (some of these exclude each other):

a large number of possible moves (i.e. lots of pieces on the board and an open position)
the mating move is done by a piece moving to the back (towards the mating player)
it is a non-standard mate (not one you have seen before in your tactics excercise, but rather of a studies type)
the mating move is a move where the moving piece uncovers a piece that helps in the check mate (either by taking away squares from the king, or more tricky by pinning a possible defender)
lots of pins are involved that prevent defenders from defending
there are tempting moves that don't work for not-too-obvious reasons
the move is an en passant capture or an underpromotion or castling
(not sure this counts) the mate requires retrograde analysis to prove that en passant capture is allowed or that castling is allowed
large distances are involved, both in the move itself and in the attacking of the king (say moving a queen from h8 to a1 to check mate a king on a8 might not be that obvious)
the position is such that the pawns move unexpectedly in a direction you would not expect (down, left, right)
asking for a mate in one  for black (without specifying that it is black's move) This can be particularly tricky if it looks as if white could mate as well.


Improvement of chess engines over time Chess engine strength has increased considerably over time due to increase of computer strength, but also improvement in algorithms/parameters.

Is there any statistics or graph out there which shows this improvement? Perhaps something like computer Elo vs time and compared to computer strength!?

There is a post about Stockfish improvement over the years.

http://talkchess.com/forum/viewtopic.php?t=62822


Stalemating the opponent in order to not lose There are some defensive ideas to get one's own king stalemated in order to not lose the game (mostly in the endgame, but sometimes also in the middle game).

Have (master) games been played where the only idea not to lose was to stalemate the opponent?
What about any legal position (which need not have occurred in a real game)?
What if you forget about the "only idea" requirement?

Edit: Although there is already a totally fine answer, I would not mind more answers using another patterns.

It's possible to build a bit on magd's answer. Consider the following position.

 [Title "White to move"]
 [SetUp "1"]
 [FEN "8/8/8/8/8/1N6/pk1K4/8 w - - 0 1"]

 1. Na1! Kxa1 2. Kc1

The only way to draw is 1. Na1! Kxa1 2.Kc1 (or 2. Kc2) stalemate. I think there are some nice studies with this theme, but I can't find them right now.


How can minimax chess engines do alpha-beta pruning without reaching the final positions? In order to calculate far ahead, minimax chess engines must perform alpha-beta pruning, where they don't calculate positions that are obviously winning or obviously losing. Without doing pruning, engines would have to deal with over a billion positions in the first 4 moves / 8 ply of the game.

My question is how do minimax engines perform alpha-beta pruning without evaluating the final positions? How does an engine know whether a position is completely won / lost without calculating as deep as it can go? For example:

e4 e5 2. Nf3 d6 3. Bc4 Bg4 4. Nc3 Nc6 5. h3 Bh5 6. Nxe5 Bxd1

At this point, White's two moves away from checkmate. Assuming the engine wasn't aware of the Legal's Mate, wouldn't it apply Alpha-Beta pruning and just stop calculating at this point, assuming the position is won for Black?

I'm aware of quiescence search, where the engine won't stop calculating until the position is considered "quiet". In this position, White is able to play Bxf7+ and Black's King is in danger, so this position wouldn't qualify as a quiet position.

But if an engine has to perform quiescence search everytime it needs to decide whether to perform Alpha-Beta pruning and stop calculating further, doesn't this defeat the purpose of pruning in the first place? Since you need to calculate ahead to check to see if you don't need to calculate ahead.

EDIT: There are two answers to this question that I found very useful. Look at SmallChess' answer for info on issues with the depth-limit of engines' calculations. See RemcoGerlich's answer for an excellent description of what Alpha-Beta pruning is. When I wrote this question I didn't truly know what it was.

If a chess engine isn't aware of the mate, then it will be happy to play the moves as Black. By the time it sees the checkmate, it'd be too late. Game over. 1-0.
Fortunately, your scenario is quite simple. A good engine should have sufficient depth to see the mate. The iterative deepening depth-first algorithm will allow searches with increasing depth limits: d,d+1,d+2,d+3... I believe any decent chess engine should be able to handle it, it's not a very deep search.
While your example is simple, pruning does cause problems for tactical positison. Take a look at Chessbase's article:

https://en.chessbase.com/post/houdini5tacticalmode
...Suppose there is a complicated position in which you just feel there must be a tactic. You could be right, but sometimes even the monster engines can miss it at first...

"Tactical mode" is a fantasy term for applying passive pruning.


Kasparov's Immortal Game. Flawed? 24...Kb6! Suggest an improvement for White Kasparov's immortal game vs Topalov is often regarded as one of the best games in chess history.

However, after analyzing it, I find that objectively speaking, Kasparov played some bad moves and got into a slightly worse position. Here, in this position below, Kasparov sacrificed his rook on d4 and Topalov made a mistake by capturing it.

    [White "Garry Kasparov"]
    [Black "Veselin Topalov"]
    [FEN "b2r3r/k4p1p/p2q1np1/NppP4/3p1Q2/P4PPB/1PP4P/1K1RR3 w - - 0 24"]

    1. Rxd4 cxd4 2. Re7+ Kb6 3. Qxd4+ Kxa5 4. b4+ Ka4 5. Qc3 Qxd5 6. Ra7 Bb7
    7. Rxb7 Qc4 8. Qxf6 Kxa3 9. Qxa6+ Kxb4 10. c3+ Kxc3 11. Qa1+ Kd2 12. Qb2+ Kd1
    13. Bf1 Rd2 14. Rd7 Rxd7 15. Bxc4 bxc4 16. Qxh8 Rd3 17. Qa8 c3 18. Qa4+ Ke1
    19. f4 f5 20. Kc1 Rd2 21. Qa7 1-0

However, if Topalov had played 24...Kb6! then Kasparov's initiative would have come to nothing.

    [White "Garry Kasparov"]
    [Black "Veselin Topalov"]
    [FEN "b2r3r/k4p1p/p2q1np1/NppP4/3p1Q2/P4PPB/1PP4P/1K1RR3 w - - 0 24"]

    1. Rxd4 Kb6! 2. b4 Qxf4 3. Rxf4 Nxd5 4. Rxf7 cxb4 5. axb4 Nxb4 6. Nb3 Bd5 7. Rf6+
    Nc6 8. f4 Rhf8 9. Rxf8 Rxf8

and Black is slightly better.

If we compare this position to the position after move 16, White does seem slightly better.

   [White "Garry Kasparov"]
   [Black "Veselin Topalov"]
   [FEN "r3k2r/1b1nqp1p/p1pp1npQ/1p2p3/3PP3/P1N2P2/1PP1N1PP/1K1R1B1R w kq - 0 13"]

The question therefore is, where did Kasparov misplay the position? How did he lose his small positional advantage. Where is the improvement for White? Or is White's positional advantage an illusion? Is the position objectively equal or even better for Black?

The question therefore is, where did Kasparov misplay the position?

No, he did not. All the lines give Black equal chances, no matter what move White chose to play.

  How did he lose his small positional advantage.

He did not lose advantage because there was none in the first place. White position just looks "prettier". He can not stop the freeing d5 break, which means that Black will eventually equalize.

  Where is the improvement for White?

At this point I see no improvement, but maybe some super computer or creative GM can find one. Time will tell.

  Or is White's positional advantage an illusion?

White has healthier pawn structure, but you do not consider Black's dynamic resources such as development advantage and active piece placement. They counterbalance White's healthier pawn structure.

After Black gets d5 break it all depends if White can punish Black for pushing too many pawns forward. To do that, he need an endgame with better pieces but that will never happen with proper play because Black has better posted and more active pieces.

White does not have an advantage, but his position is "prettier" due to the healthier pawn structure. Again I point out that black has better piece placement, and can liquidate the d6 backward pawn after which things are unclear.

  Is the position objectively equal or even better for Black?

I will quote Mr.Kasparov himself from Chess Informant 74 :

[fen "2kr3r/1b2qp1p/pn1p1npQ/1pp5/4P3/PNN2P2/1PP3PP/1K1R1B1R w - - 2 16"]

1.Na5 ( 1.a4?! b4 2.a5 bxc3 3.axb6 Nd7=/+ ) 1...d5 2.Nxb7 ( 2.g3 b4∞ ) 2...Kxb7 3.exd5 Nbxd5 4.Nxd5 Nxd5 5.Bd3 f5 6.Rhe1 Qc7 7.Bf1 c4∞

Here is the zip file that holds almost every published analysis of this game, including Kasparov's comments after the game. It was also instructive to go through the comments of top GMs as well as other "lesser players" who used engines for the analysis. Just click on the spinning red box:

SUMMARY:

Although White has better pawn structure, he is behind in development and his queen is misplaced.

Black does have a backward pawn on d6 and has compromised his pawn structure on both wings but that is not so bad for him since his pawns restrict the opposing light pieces. He has more space on the queenside and a chance to obtain initiative on that part of the board, while his holes on dark squares on the kingside can not be effectively exploited. He has wonderful piece coordination and activity and will achieve the freeing d5 break, eliminating the weakest piece in his setup, thus achieving full equality.

I evaluate this position as sharp/unclear with equal chances for both sides.

As for Topalov losing this one, you must be aware that Kasparov tried a3 as a novelty, which probably threw Topalov out of balance a little, so he misplayed it in the end. He was probably in time pressure, or simply lost focus due to calculating all the possibilities in a new position which is always a difficult task. Up until cxd4? he played well, even Kasparov had to award exclamation points for some of his moves.

Hopefully this helps. If you have further questions leave a comment.

Best regards.


Is this endgame winnable (for White)? I ran into this position during a game against a computer, but I'm not sure if its winnable (I'm, White). Also, any comments on my play/computer's play would be highly appreciated.

I'm not sure how to use this site's chess diagrams, so I'll just post the PGN file here:

[FEN ""]
1. e4 e6 2. d3 d5 3. exd5 exd5 4. c3 Bd6 5. g3 Ne7 6. Bg2 O-O 7. Nf3 Re8 8. O-O Nbc6 9. Be3 Nf5 10. Re1 Nxe3 11. Rxe3 Rxe3 12. fxe3 Qe7 13. Qe2 Bg4 14. Nbd2 Re8 15. e4 f5 16. Re1 fxe4 17. dxe4 Ne5 18. Qe3 Bxf3 19. Nxf3 Nxf3+ 20. Qxf3 c6 21. a3 Qe6 22. b4 Kh8 23. Qd3 Bc7 24. Kh1 Kg8 25. Qd4 Bb6 26. Qd3 Bc7 27. a4 b6 28. Qd4 Qe5 29. Kg1 Qe6 30. Qd2 Qe5 31. Re3 Re6 32. Qf2 Re8 33. Kh1 Qe6 34. Qf3 Kh8 35. h3 Kg8 36. Kh2 c5 37. Qg4 Qe5 38. Qd7 Rd8 39. Qf5 Qxf5 40. exf5 cxb4 41. cxb4 Kf7 42. Rd3 d4 43. Be4 Be5 44. Kg2 Kf6 45. g4 Rc8 46. Kf3 Rc4 47. Bd5 Rc1 48. Bg8 h5 49. Bb3 Rf1+ 50. Kg2 Rf4 51. Bd1 a6 52. b5 axb5 53. axb5 Re4 54. Ra3 Re1 55. Rd3 Re4 56. Ra3 Re1 57. Rd3 hxg4 58. hxg4 Re4 59. Kf3 Rf4+ 60. Kg2 Ke7 61. Kh3 Rf2 62. Kh4 Kf6 63. Rf3 Rxf3 64. Bxf3 d3 *

Obviously, white can't win. Let white do any move except g5+ (Kh5, for example)
65... g5 66. fxg6 Kg7 Now black bishop will move on squares c5 and g1 and white can't do any progress because pawns are blocked.

Moreover, I like black's position more,


Is there an engine evaluation technique that factors in 'time'? An interesting game played out between Wesley So and Levon Aronion1:
[title "Wesley So vs Levon Aronian"]
[fen "rn4k1/p2bP1b1/2q5/1pp2p1Q/2p5/8/PP3PPP/3R1RK1 w - - 0 1"]

So was in a far superior position according to the computer, but had only ~1 minute compared to Aronian's ~5 minutes.
Is there any established system for evaluating positions taking into account time for both players?
1 Link to game: https://www.chess.com/events/2021-magnus-carlsen-invitational-prelims/06/So_Wesley-Aronian_Levon

Is there any established system for evaluating positions taking into account time for both players?

No, there isn't. This is for two main reasons:

There is no objective measure for how time affects a player's ability to play any given position.
Such evaluations would be useless. They would literally tell you nothing useful

Let me give an example from a game one of my clubmates (rated about 1800 at the time) played a few years ago in the UK National Universities Championships.
In the blitz section (3+2) in one of his games he reached a KBN vs K endgame with less than 30 seconds left on the clock. He knows that endgame (he has a strict coach who makes him learn that kind of stuff) and so blitzed out the win with plenty of time to spare on his clock.
I also have stronger clubmates (2100+), however, who don't know that endgame. They would never be able to mate in so little time. Give them 20 minutes on the clock and maybe they'd succeed. There have even been IMs who have failed with plenty of time on the clock.
Bottom line: even with as simple a position as this there is no way to provide a meaningful evaluation of the position that takes time into consideration.


Latest time to castle in a tournament game In a casual game I played, my opponent castled around the 80th move. I want to know what was the latest move in which a player has castled, in an official game. I don’t think that there is an entry for this on Krabbe’s record site.

This web page claims that "[the] latest castling was performed on move 48 in two games: Neshewat – Garrison, Detroit 1994 and Somogyi – Black, New York 2002."
According to https://www.chessgames.com, the first was Michigan Class A (1994), Detroit, MI USA, rd 2, Jan-15. That site gives that second game here with no tournament or match citation. These are actually both on Tim Krabbe's record page under the title "Latest castling" in the "Moves" section.
Game 1: Kingside Castling
[Title "Neshewat-Garrison, Detroit, 1994"]
[FEN ""]

1. d4 Nf6 2. c4 c5 3. Nf3 cxd4 4. Nxd4 Qa5+ 5. Bd2 Qb6 6. Nb3 Ne4 7. e3 Qf6 8. Qf3 Qxf3 9. gxf3 Nxd2 10. N1xd2 Nc6 11. a3 d6 12. Be2 g6 13. Rb1 a5 14. O-O a4 15. Nc1 Bf5 16. e4 Be6 17. Rd1 Bh6 18. Kg2 Nd4 19. Bd3 Ra5 20. Nf1 Rg5+ 21. Ng3 Nxf3 22. b4 Bg7 23. Be2 Nh4+ 24. Kh1 Bh3 25. f4 Bg2+ 26. Kg1 Bxe4 27. Nd3 Bd4+ 28. Kf1 Rxg3 29. hxg3 Nf5 30. Rdc1 Nxg3+ 31. Ke1 Be3 32. Rd1 Nf5 33. Rb2 Bd4 34. Ra2 Ne3 35. Rc1 Ng2+ 36. Kf1 Be3 37. Rc3 Bd4 38. Rc1 Be3 39. Rb1 Nxf4 40. Rd1  Ne6 41. Nf2 Bf5 42. Bd3 Nd4 43. Bxf5 Nxf5 44. Ke2 Bh6 45. Ne4 Bg7 46. c5 dxc5 47. Nxc5 Nd4+ 48. Kf2 O-O 49. Nxa4 e5 50. Nc5 Nb5 51. Rd7 b6 52. Rb7 Nc3 53. Rc2 e4 54. Rxb6 e3+ 55. Ke1 Rd8 56. Rc1 h5

Game 2: Queenside Castling
[Title "Somogyi-Black E., New York, 2002 "]
[FEN ""]

1. e4 g6 2. d4 Bg7 3. Nc3 b6 4. Nf3 Bb7 5. Bf4 Nf6 6. Bc4 Nc6 7. O-O Nxe4 8. Nxe4 d5 9. Bd3 dxe4 10. Bxe4 e6 11. c3 Qe7 12. Ne5 Bxe5 13. dxe5 Na5 14. Bd3 a6 15. Qg4 h5 16. Qg3 h4 17. Qe3 Qd7 18. f3 Nc6 19. Rad1 Ne7 20. Bg5 h3 21. g4 Nd5 22. Qf2 c5 23. a3 Qc7 24. c4 Ne7 25. Qg3 Nc6 26. Bf6 Rh7 27. Rf2 Nd4 28. Bf1 b5 29. b4 bxc4 30. Bxc4 Qc6 31. Rd3 a5 32. b5 Qd7 33. a4 Bd5 34. Rc3 Bxc4 35. Rxc4 Qd5 36. Rc1 Nb3 37. Re1 c4 38. f4 Nc5 39. Qa3 Qd4 40. Qf3 Qd5 41. Qxd5 exd5 42. Rd1 Ne4 43. Rc2 Nxf6 44. exf6 Rh4 45. g5 Rg4+ 46. Kh1 Rxf4 47. Re2+ Re4 48. Rde1 O-O-O 49. Rxe4 dxe4 50. Kg1 Kb7 51. Rc1 Rd2 52. Rxc4 e3 53. Rc1 Rg2+ 54. Kh1 Rg4 55. Re1 Rxa4


What is the longest forced mate optimally played in documented competition? There are tons of questions about the longest forced mate on here and other chess forums. Usually the answers are the 2 Knights forced mate and another one that evidently takes 549 optimal moves. Ultimately those discussions often devolve into debate about the 50 move rule.

However as a novice player it often boggles my mind when, in real games, players are able to recognize unavoidable checkmate on a non-empty board dozens of moves in advance. Hence, what I am wondering about is: what is the longest forced mate optimally played in documented competition? In other words, in competitive play (international, national, league, etc.), what comes to mind as the furthest time (in moves) from checkmate when resistance is futile? Something a la "that's mate in 15."

Edit: I imagine that this situation usually brings about resignation, so I should clarify that I'm not interested in if it was ever played out, but rather what the maximum number of moves was in advance of checkmate when this futility was ensured.

I discovered a game from a few weeks ago features a forced mate in 13 moves that was actually played out on the board.

The game in question is Dubov-Svane, and the claim for the mate in 13 comes from Agadmator’s analysis video of the game.

Testing the given position with the chess.com engine yields a mate in 13, so Agadmator is correct. But Black made a mistake in the real game, shortening the game, but overall, it is still a forced mate in 13 moves in my opinion.

What Black should have played is included as a sideline.

[Title "Daniil Dubov-Rasmus Svane. European Team Championship, Batumi, Georgia, 10/31/19"]
[FEN ""]
[startply "58"]

1. c4 e6 2. Nc3 d5 3. d4 Nf6 4. Nf3 Be7 5. Bf4 O-O 6. e3 b6 7. Qc2 Ba6 8. O-O-O dxc4 9. Ng5 Nc6 10. a3 g6 11. h4 Bd6 12. g3 Qe7 13. h5 e5 14. hxg6 hxg6 15. Bg2 exf4 16. Bxc6 fxg3 17. Kb1 Rad8 18. f4 Bc8 19. Rde1 Kg7 20. Nd5 Nxd5 21. Rh7+ Kg8 22. Rxf7 Rxf7 23. Qxg6+ Kf8 24. Qh6+ Rg7 25. Bxd5 Ke8 26. Qh5+ Kd7 27. Qh3+ Ke8 28. Qh5+ Kd7 29. Be6+ Kc6 30. Qf3+ Kb5 31. Bxc4+ Ka5 32. Qd5+ Bc5 33. b4+ Ka4 34. Qg2 (34... Bf5+ 35. Ka2 Rd5 36. Qxd5 Qd7 37. Qb7 a5 38. Ne4 Bxd4 39. exd4 Bxe4 40. Qxe4 Qf5 41. Qxf5 axb4 42. Bb3#) Bxb4 35. Qc6+ Kxa3 36. Bb3 Bd7 37. Qc1+ Kxb3 38. Qc2+ Ka3 39. Qa2#


Are there any opening traps that result in a windmill? Are there any opening traps where your opponent can blunder into a windmill?

I did some deep, deep searching and found few results. It seems that there are no actual windmill traps that are quick and widely known. This is unless you somehow manage to run through long and arbitrary sequences that are extremely unlikely to occur in actual play. Even then, it is a matter of your opponent who actually falls for it.
If you still consider it a trap though, the one genuine such trap that I have discovered so far occurs in the Russian Game, Damiano Variation.
[FEN ""]
[startply "26"]

1. e4 e5 2. Nf3 Nf6 3. Nxe5 Nxe4 4. Qe2 Qe7 5. Qxe4 d6 6. d4 dxe5 7. Qxe5 Qxe5+ 8. dxe5 Nc6 9. Bb5 Bd7 10. Bxc6 Bxc6 11. O-O O-O-O 12. Bf4 g5 13. Bxg5 Rg8 14. Bxd8 Rxg2+ 15. Kh1 Rxf2+ 16. Kg1 Rg2+ 17. Kh1 Rg3+ 18. Rf3 Bxf3#

The trap occurs when Black plays 13... Rg8. If White strikes the false prey with the move 14. Bxd8?, thinking they have won an exchange, then Black can play 14... Rxg2! and commence a mate in 4 using the windmill tactic.
Another alternative, as @supercat suggested in a comment, is that Black could troll some and have fun demonstrating the power of the windmill.
[FEN "2kB1b2/ppp2p1p/2b5/4P3/8/8/PPP2PrP/RN3R1K b - - 0 1"]

1... Rxf2+ 2. Kg1 Rg2+ 3. Kh1 Rxc2+ 4. Kg1 Rg2+ 5. Kh1 Rxb2+ 6. Kg1 Rg2+ 7. Kh1 Rxa2+ 8. Rf3 Bxf3+ 9. Kg1 Bc5+ 10. Kf1 Rxh2 11. Ke1 Be3 12. Nd2 Bxd2+ 13. Kf1 Be3 14. Ke1 Rh1#


Promotion race between three non-confronting pawns Two evenly matched players have reached the endgame after exchanging off all their pieces except the King and 3 Pawns. Having castled on opposite sides, we have now reached the following interesting position.

8/pppk4/8/8/8/8/4KPPP/8 w - - 0 1

Quite clearly, this is now a race for pawn promotion. What should be the strategy in this position (for both players)? Should your King go after the enemy pawns, or lead your own pawns to promotion?

The two previous answers both suggested that this position is a draw, but I believe it's a win for White.

Stockfish 5 evaluates the position at more than +10 if left to run for long enough (e.g., to depth 40), which sounds pretty decisive, but of course Stockfish isn't infallible. I generated a FinalGen tablebase for the position, but unfortunately it wasn't able to solve the position fully, though it did show that the moves 1.Kf3 and 1.Kf1 lose. Stockfish evaluations for the positions after 1.Kf3 and 1.Kf1 eventually drop below -10, which suggests that Stockfish does understand what is going on here, and its evaluations (at depth 40 or more) should be taken seriously.

The question, of course, wasn't about the game-theoretic status of the position, but about the strategy. The basic strategy is to block the opponent's pawns and aim for zugzwang. White's first move appears to give him a decisive advantage in doing this, provided he starts by moving his king towards the queenside (1.Kd1, 1.Kd2 or 1.Kd3). Here's a sample line:

[FEN "8/pppk4/8/8/8/8/4KPPP/8 w - - 0 1"]

1.Kd3 Ke6 2.h4 Kf7 3.h5 Kg7
( 3...a5 4.Kc4 a4 5.Kb4 b5 6.f4 c5+ 7.Ka3 c4 8.Kb4 Kg7
( 8...Kf6 9.g4 Kg7 10.f5 )
9.f5 Kg8 10.g3 Kg7 11.g4 Kg8 12.h6 Kh7 13.g5 Kg8 14.g6 Kf8 15.f6 $18 )
4.g4 Kh6 5.Kc3 a5 6.f4 a4 7.f5 Kg5
{ The kingside is now mutual zugzwang: Black can't move there without allowing promotion, and White can't move there without losing a pawn. Play therefore switches to the queenside. }
( 7...b5 8.f6 $18 )
8.Kb4 b5 9.Ka3 c5 ( 9...c6 10.Kb4 c5+ 11.Ka3 c4 12.Kb4 $23 { Zugzwang. } )
10.Ka2 b4 11.Kb2 a3+ 12.Kb3 c4+ 13.Ka2 c3 14.Kb3
{ The queenside is now also mutual zugzwang, so Black to move loses. }
14...c2 15.Kxc2 a2 16.Kb2 b3 17.Ka1 Kf6 18.h6 Kf7 19.g5 Kg8 20.g6 Kf8 21.f6 1-0

Black could try to avoid zugzwang by mimicking White's moves, but he can't mimic checks, and this is in any case a recipe for losing a direct race to promote. Here's a sample line:

[FEN "8/pppk4/8/8/8/8/4KPPP/8 w - - 0 1"]

1.Kd3 Ke6 2.h4 a5 3.Kc4 Kf5 4.h5 a4 5.g4+ Kg5 6.Kb4 b5 7.f4+ Kh6 8.f5 c5+
9.Ka3 c4 10.f6 c3 11.g5+ Kxg5 12.f7 b4+ 13.Ka2 b3+ 14.Kb1 a3 15.f8=Q a2+
16.Ka1 c2 17.Qc5+ 1-0


How many initial moves are possible in Chess, 20 or 21? Each pawn, of which there are 8 white, can move 1 or 2 squares forward.
Each knight, of which there are 2 white can move forward and left or forward and right.

That gives 20.

But white can also resign, and in some tournament situations this might be sensible.

But is resignation a move?

I sometimes attend quiz nights and this is a common question, and the answer is always said to be 20. I,  however, always say it is really 21 because of the resignation option. But, is resignation actually a move?

Your question essentially reduces to asking whether resignation is considered a move or not. To be exact, you are asking about legal moves, the topic of which is addressed in (and defined by) Article 3 of the Laws of Chess. Resignation isn't mentioned there, so it's not a move.

A heuristic argument: you are allowed to make a move and then resign immediately, i.e. if resignation was a move, you have effectively made two consecutive moves, which is not allowed.

Or more simply: since you can resign even when it's not your move, it follows that resignation is not considered a move.


Who did Kasparov call a talented amateur? I heard that Kasparov called some strong player a talented amateur? Who was that? Thanks.

I will answer in the first line of the next paragraph, but there is a lot of history that happened right around the time Kasparov made this comment, so I will add in some of that too.

At the Tilburg tournament in November 1997, Kasparov was not known for holding his tongue, and he called Grandmaster Shirov, who was 2700 and 8th in the world, a "talented amateur". Shirov did not appreciate the remark. Kasparov’s comment is ironic since it was only about a year later that Shirov would upset Kramnik in a match (5.5-3.5) to win the right to play Kasparov for the PCA (Professional Chess Association) World Championship in 1998, but the match never took place because there was no sponsor since Intel, and later Linares organizer Luis Rentero, pulled out, and the money could not be secured. The PCA collapsed. Shirov was probably not without blame as it is alleged that he refused to play since his cut was too small.

My opinion is that if you are not champion, you should play, and if you win, then you have more leverage…get paid big down the line. That said, it is a big stretch to think that Shirov would have beaten Kasparov anyway as Shirov was Kasparov’s “customer”, meaning that Kasparov beat him like a drum throughout their career. The lifetime record was 16 wins, 15 draws, and zero losses for Kasparov.

After this happened, a new sponsor, BrainGames.com, was eventually secured for a Kasparov match, but unfortunately, the sponsor tried to sign Anand to play Kasparov, but this fell through too. Shirov was naturally upset that he was not signed, and called Anand a “pickpocket”, and he felt that Kasparov had to play him before he played any other matches. It turned out that since even that match never took place, Kasparov ultimately played Kramnik in 2000, and well, we know how that turned out: Kramink, a heavy underdog, used the Berlin Defense to the Ruy Lopez, and won by a score of 8 1/2–6 ½. Anand would go on to win the separate FIDE World Championship knockout event that year as Kasparov had previously broken away with the classical title in 1986.


chess24 castling rules Can someone explain to me, why on chess24.com white cannot castle in the situation in the picture? King never moved, neither did either of the rooks. When the queen was moved to d2 castling was not allowed queenside either. When I take the moves from the game and import to lichess, castling is allowed there. What am I missing?

After clicking on the king, the rook is outlined in green, as shown in your both your own image, and mine below.

If you click the rook after clicking the king, castling will occur, shown in the image below:


How do i prevent blunders? Playing Online Chess seems to get rid of my bad blunders but after playing with little kids on a real match, I've made a very stupid blunder that decided the game.

Can't post the game, not recorded since It's a game played with kids.

You need to stop playing "Hope Chess" and start playing "Real Chess."

Dan Heisman gives the definition of Hope Chess as follows:

  "HOPE" Chess - This is NOT when you make a move and hope your opponent
  doesn't see your threat. Instead, Hope chess is when you make a move
  and don't look at what your opponent might threaten on his next move,
  and whether you can meet that threat on your next move. Instead, you
  just wait until next move and see what he does, and then hope you can
  meet any threats. In my first 3 tournaments I played Hope chess and
  never won more than 1 game in any of the three. The speed at which you
  can play Hope chess also explains why I usually took only about half
  an hour for each game in these tournaments, even though the time
  control was 50 moves in 2 hours. Most high school level players play
  hope chess, but almost always lose when they run into a serious player
  who plays "Real Chess."

NM Heisman gives his simplified "Real Chess" thought process:

1) How the opponent's move changed the position and if threaten to do something positive.

2) What the goal/plan is for the position.

3) What the candidate moves are. A candidate move is a move that might do something positive, so you should at least look at it.

4) Which of the moves are safe. Omitting this step is Hope Chess.

5) Which of the safe candidates moves is best. At the end of this step, do a blunder check.

If you wait until the blunder check to make sure all responses to your move do not cause you to lose the game, this will limit your results. I used to play this way and could not get over 1300.


Building a chess using magic bitboard... how do I know if the movement is valid OK I have read a lot of things on the web most of them using Java that doesn't have unsigned int. I am working on Objective-C that has unsigned int.

Lets consider the following scenario.

The board is like this:

A1 is on the lower left and is the least significant bit and H8 is on the top right and is the most significant bit.

I have constructed the bitmasks for the movements of all pieces for all positions on the board.

Suppose the following simple situation:

the game will start. All pieces are on their initial positions.
the user tries to move the knight on G1 to E2.

Obviously this movement is impossible because there is a pawn on E2.

How do I discover if a movement is valid?

Ok I have the bitmask of all pieces that is this:

1111111111111111000000000000000000000000000000001111111111111111

and I have the bitmask of the possible movements for the knight at G1 that is

00000000
00000000
00000000
00000000
00000000
00000X0X
0000X000
00000000

or in bits

0000000000001000000001010000000000000000000000000000000000000000

if I AND these two

1111111111111111000000000000000000000000000000001111111111111111
0000000000001000000001010000000000000000000000000000000000000000

I get

0000000000001000000000000000000000000000000000000000000000000000

all I know is that there is a piece at that point but I am not seeing how this tells me if that is a valid move or not.

Another question is this: suppose this move would let my king under attack. Obviously the move would be technically possible under the knight rules of movement but impossible because I cannot do a move that puts my king under attack.

How do I get these informations? Thanks

Make a bitboard of all the white pieces.  If the AND of the possible knight move and the white pieces is TRUE, then the move is illegal--attempting to capture your own piece.

The simplest way is to make the move and check if the King is in check.

The method I use is a little more complicated.  First I check is the King is in check now.  If the King is in check, I can delete all non-king moves which do not finish on the line the check is coming from.  If the King is not in check, I only have to check the line if the piece moves from the line.  The code seems harder to write, but the validating routine runs less lines.

To explain the latter case better.  If the King on f1 is not in check, and I move the Knight on f3, I only have to examine if a check was masked by this Knight.  If a Bishop moved from d3, I only have to examine if the opponent's Bishop or Queen is checking from c4, b5 or a6.


Defensive strategy relying on a wall of pawns I have been playing chess again for two or three months, after a period of about twenty years of interruption. In a game against a human adversary, I noticed that my opponent was taking the time to build a large wall of pawns similar to the following picture, while I was on my side playing with stronger pieces.

8/8/8/8/P1P1P1P1/1P1P1P1P/8/8 w KQkq - 0 1

I found quite difficult to play aggressively against such a wall. Recently I tried the same and found this strategy rather efficient (of course the wall is never perfect but the picture gives the idea).

I would like to know a little more about this style of playing. Does it have a name? Is it known to be efficient?

I would say that type of formation leaves a lot of weak squares, as enemy pieces can occupy pretty much any dark square they want (mainly b4, d4, f4, h4) and start an attack from there with help from the pawns. These pieces will never ever be kicked away. White's light squared-bishop will also suffer because he has nowhere to go, so, for that strategy to be effective:

White needs to have traded his light-squared bishop beforehand, or else pretty much any bishop vs knight endgame will be lost.
White must keep his dark-squared bishop at all cost, or else Black's bishop could be very harmful
White needs to know what to do about enemy knights on f4 and d4.
Pawn breakthroughs near White's king must somehow be prevented (for example, if Black castles in the kingside, ...h7-h5 must be somehow prevented)

In short, I don't like that kind of "wall" at all. And we haven't even talked about the at least eight moves it requires to build it, in which you can develop pretty much all of your pieces. Sometimes a c3-d4-e3-f4 formation is built (Stonewall Dutch), but this is only four moves and only leaves one weak square (e4) rather than four. So, occupy the dark squares, open a file and checkmate your opponent! If you want, post an example game where you've struggled against the "wall", and we can see what else could have being played


Which FIDE rule forbids pressing the clock before taking captured pieces off the board? A long time ago I used to play OTB blitz chess at a chess club. We  had club blitz tournaments  [5 mins each with no increment because the clocks were old-school chess clocks]. I was new to blitz. I had a habit when taking off material, such as an exchange, of pressing my clock with my hands still on the board and being yet to take off the material. This ate into my opponent's time. One strong opponent who was an official chess arbiter once responded by pressing my own clock and saying "move on your own time".

I agree that my habit was wrong. I tried to stop doing it. Where in the FIDE laws of chess would it cover this habit?

It sounds like you were breaking the rules on several fronts.

According to the FIDE Laws of Chess:

  6.2.3 A player must press his clock with the same hand with which he made his move. It is forbidden for a player to keep his finger on the
  clock or to ‘hover’ over it.

You would probably be punished under the illegal move rules:

  7.5.2 If the player has moved a pawn to the furthest distant rank, pressed the clock, but not replaced the pawn with a new piece, the
  move is illegal. The pawn shall be replaced by a queen of the same
  colour as the pawn.

  7.5.3 If the player presses the clock without making a move, it shall be considered and penalized as if an illegal move.

  7.5.4 If a player uses two hands to make a single move (for example in case of castling, capturing or promotion) and pressed the clock, it
  shall be considered and penalized as if an illegal move.

  7.5.5 After the action taken under Article 7.5.1, 7.5.2, 7.5.3 or 7.5.4 for the first completed illegal move by a player, the arbiter shall give two minutes extra time to his opponent; for the second
  completed illegal move by the same player the arbiter shall declare
  the game lost by this player. However, the game is drawn if the
  position is such that the opponent cannot checkmate the player’s king
  by any possible series of legal moves.

It sounds like you were either moving with one hand and pressing the clock - 6.2.3 or using two hands to make the move - 7.5.4


How many 2200+ FIDE rated players are there? Are there any sources for the recent numbers of players rated over 2200 byFIDE?

According to FIDE, there are 20,763 players rated 2200 or above (as of May 2021). 9,460 are currently active


Refutation to the Stafford Gambit "magic line" I thought I had finally discovered a cure-all to the mainline Stafford gambit that's made waves on youtube, but as soon as I felt like I found lines where black can't possibly get enough play, the biggest Stafford exponents of this so-called "magic line" seem to have found improvements that still give black chances. The line I am discussing here begins after 8...Qh4!:
[FEN ""]
1. e4 e5 2. Nf3 Nf6 3. Nxe5 Nc6 4. Nxc6 dxc6 {The Stafford Gambit. White has many tries, but there's really only one way black can make white's life uncomfortable in the mainline that I am trying to analyze - the so-called "magic line":} 5. d3 Bc5 6. Be2 h5 (6... Ng4?! 7. Bxg4 Qh4! 8. g3 Qxg4 9. Qxg4 Bxg4 10. Nd2 O-O-O 11. O-O Bh3 12. Re1)  (6... O-O?? 7. c3 Re8 8. O-O) 7. c3 Ng4 8. d4 Qh4 9. g3 Qf6 10. f3 h4 11. fxg4 {I believe this is white's best move and I'm mostly looking for improvements beyond this point} hxg3 12. Be3 12... Rxh2 13. Rg1 Qh4 14. dxc5 (14. Nd2!? 14... Be7 15. Nf3 Qh7 16. Nxh2 gxh2 17. Rh1 Qxe4 18. Kd2!!) 14... Be6 (14... Bxg4? 15. Bxg4 Rd8 16. Bd4 g2+ 17. Kd2 Qf2+ 18. Kd3!! (18. Kc1?? Rxd4!! 19. cxd4 Qxg1!! 20. Qxg1 Rh1)) 15. Na3 Rd8 16. Bd4 b6!! {Leela suggestion that keeps the position uncomfortable} 17. cxb6 axb6 18. Qd3 c5 19. O-O-O cxd4 20. cxd4

There are certainly many alternatives for both players throughout this analysis. One extremely interesting game between Jonathan Schrantz and Stockfish occurred after 11. dxc5 Be6!! 12. Qd4 Ne5! and he was able to get a draw (https://www.youtube.com/watch?v=Qp75rbkIAYU). Another interesting game between IM Eric Rosen and IM halfnatty on lichess went 15. Nd2? O-O-O 16. Qa4?? Rxe2 and black won immediately (https://www.youtube.com/watch?v=68H5DnAVQwo). I inserted my only game in this line into the above analysis, where we both made mutual blunders on move 14 and 18 just to highlight some of the ways this can go horribly wrong (https://www.youtube.com/watch?v=qcfifxkyC8A).
Looking forward to people's feedback on these positions. Did I miss any important tries for black? Are there easier ways forward for white? Throughout this line, Stockfish says +5 or more, but Leela seems to like black's chances a lot more... needless to say, it's all incredibly complicated.

one improvement could be on move 11. Rg1 rather than 11.f.g4, though they are both good,
also on move 15. Na3 doesn't make sense, 15Bd4 with the idea of Qd3 is more playable, aslo g5 could be considered too,
but I'd agree with the comments by Pablo, it is not worth your time and it is a dubious gambit, just play either Nc3 and get a playable game, there are much more to learn that just some second hand gambit, unless you just want to play blitz and have no ambition to be better OTB player.


Concentration during games I've noticed that I lose sight of pieces' positions very fast during games, also, for some reason, I fail at having an "objective" view, some kind of an eagle eye, i.e I find myself concentrated on where the action is, the 3 or 4 squares related to the last move, this is obviously a default in me and would really wish to get helpful advice from you lots.

I think I am the best person to answer this question as I have come across a similar kind of situation.

I would suggest you to first focus on whether you are losing your pieces by any opponent's strategy. Don't directly play with a high level opponent . For increasing your alertness, you can play chess on computer at a lower level and then gradually increase it once you start winning. 'Chess titans', for example, on Windows 7 is an excellent game to improve firstly your alertness, then the logical skills , and finally patience. Try to analyze what is happening on the board instead of narrowing your vision to 3-4 squares. This will greatly benefit you, my friend.

Now, we turn to logical skills. The most important thing here is to predict your opponent's move and develop your strategy to make him/her fall into your trap. Try to think simple rather than complicating situations. I would also suggest you to be calculative while playing. Here I mean to say that you should be able to think what is going to happen on the board after 2-3 moves. Thereafter, increase the count. I know that it is not possible in all situations, but try to exploit the situations where it works.

Finally,  patience. Patience , in any work, is the key to success. You can also calculate and plan your next moves while your opponent is planning his/her next move. Also you can try to be ahead of your opponent in calculations. For example , if your opponent has calculated what is going to happen in the next three moves, and if you have calculated upto 4 moves, then you have an edge over your opponent.

These simple techniques have helped me in overcoming my problems and I hope these will be beneficial for you too.


What's the oldest age at which a grandmaster played their first rated game? Of all grandmasters past and present, what is the oldest age at which any of them started playing chess?
Define started playing chess:

The day that person played their first (FIDE, or equivalent) rated game

This isn't an answer to the exact question posed, but it may nonetheless help.
Lajos Portisch learnt to play aged 12.
Akiba Rubinstein learnt at 14 or 16. (Sources vary.)
Harry Pillsbury learnt at 16.


11. ..Qg5 in Svesnikov possible? As a Svesnikvov player (rated ~1800) the following idea was shown to me recently:

[Title "11. ..Qg5!?"]
[StartFlipped "1"]
[fen "rnbqkbnr/pppppppp/8/8/8/8/PPPPPPPP/RNBQKBNR w KQkq - 0 1"]

1.e4 c5 2.Nf3 Nc6 3.d4 cxd4 4.Nxd4 Nf6 5.Nc3 e5 6.Ndb5 d6 7.Bg5 a6 8.Na3 b5 9.Bxf6 gxf6 10.Nd5 f5 11.Bd3 Qg5!?

It seems quite interesting. At least 12. Nc7+ grabbing the rook leads to a nice game for Black. However White is not forced to do that.

g3 is the obvious alternative, when 12. ..Rb8 seems playable. Maybe one can sac the rook even here?

However 12. ef is the computer‘s choice. The tactical point is that 12. ..Qxg2 13. Nf6+ K somewhere Be4 is just horrible for Black – and in many other variations he has problems getting the pawn back. After guarding the fork with Kd8 (or sth. else? Maybe saving the rook ist not necessary here?) White can castle. And whenever Black tries to get his pawn Back, White plays f4 with a great game. The best I found here was some line where Black got an ending with a horrible Bishop and worse pawn structure – also not very satisfying.

I‘d like to apply such a move against stronger opponents (rated 2000+, even 2200+ [in a Swiss tournament I could face such opponents]), where my "normal" winning or even drawing chances are not that great. So it is not that big of a deal if I get a slightly worse game, but I want to have great fighting chances – and the advantage that I have pre-analysed the position at home. I am also willing to give away "some" material (the f5 pawn, the a8 rook) for a nice attack. I just do not want to play the line the computer recommends after 12. ef – that‘s definitely not a position I can hold against a stronger opponent.

So my question is: Do you have any experience playing this line? Are many players aware of 12. ef or find that move on the board? Is there a more fighting continuation (which may be objectively worse, but where White has to play very precise)? If White does not grab the rook right away with 12. Nc7+, do I really have to protect it next move? For example, after 12. g3, does Black have (crazy?) attacking chances, if he gives up his rook?

I do not want to discuss the concept of playing an objectively worse move against a stronger opponent just to get some chances, if he fails to find the best moves. Both "Forget about 11. ..Qg5, just spend your time on analysing 11. ..Be6 and try to beat your opponents there" or "play the board, not the player!" may (or may not) be reasonable suggestions, but they are of no interest here.

I looked at that line a few years back, with the same intention of surprising stronger players. But I never played it in a tournament game and my blitz games didn't lead to particularly positive emotions …

I think 12.ef definitely can be found by a decent player and the only reason why people probably won't play it is, that there is an abundance of good other, more solid, moves. If I remember correctly even 12.g4 can be played.

No strong player will just grab the rook against a weaker player, if he has never seen the line before. Actually I think, that this kind of semi-bluff works better if grabbing material is the only decent way to continue.

So my conclusion was that 11…Qg5 means taking a risk without having a realistic hope of getting a reward. You would have to prepare against 12.Nc7, g3, g4, ef, Qf3, 0-0 and none of these moves is even an outright blunder for white!

If you want to lead your opponent on a very narrow path through the jungle, that only one can leave alive, make sure the path is not just narrow for yourself.