What thought process should one use to find candidate moves? Do you have a thought process for finding candidate moves?

Once you find all possible candidate moves, how do you narrow it down to your final choice?

Regarding the process, do you have a certain order of things you look at or is it in a random order?

Here is a basic checklist you should always consider (in order of priority):

Examine all tactics currently available to both players on the board within the next move; these take priority. Usually, each tactic has a purpose, such as check-mate (highest priority), winning material (secondary-priority) and securing a very strong position (tertiary-priority.)

In the case of an opponent's tactics, search for "in-between" moves in the execution of the tactic. Many times one non-obvious in-between move can spell the difference between a beautiful defence and losing the game. To give an example of an "in-between" move, suppose your opponent has a discovered attack ready on your queen using a knight and a bishop. His goal is to win a rook for his knight by using the discovered attack and simultaneously attacking your rook and queen. He does not realize that your queen has an "in-between" check move allowing her to move to safety as well as your rook.
In the case of tactics available to you, also search for all "in-between" defensive moves available to your opponent. For example, suppose the previous example of the knight, bishop discovered attack on the queen was actually your tactic. After thoroughly investigating your opponent's options, you realize he can check and move his queen to safety with the in-between move. Therefore, you move your king to a square where a check is not possible, forcing the queen to move to a worse position this turn else face the wrath of the tactic the next turn.

Search all available tactics (as thoroughly as above) within 2,3,4, ... n moves where n is limited by the amount of time you have on the clock and your gut-feel for how important this position is vs. how sure you are your current best move is.
Search for guaranteed positional weaknesses in your opponent. In the lack of tactics available in the game, it can be hard to find a reason to play one move vs another. This may be a daunting task for a beginner, but rest assured there is almost always a best move. Almost all positional weaknesses deal with pawn positioning, specifically the colour your pawn chain sits on, or lack of being able to form pawn chains. In order to achieve positional weakness in your opponent, you may have to do it through a tactic so keep that in mind. I'll list some common positional weaknesses:

A knight placed where an enemy pawn can not "kick" him off is substantially stronger when placed close to an enemy king. This is called a knight on an outpost. This is mainly because it opens up the possibility of many forking tactics. Often, when your opponent has no other means of kicking your knight, such a knight is worth at least 1 rook, sometimes 1 rook and a pawn.
Doubled-pawns create long term weaknesses since they can no longer form pawn chains in one direction. DO NOT consider this a considerable weakness in the early or middle game, because it is not, it is only a weakness in the endgame. Doubled pawns near their king, especially if he is castled, are always a weakness at every point in the game.
The colour your opponent's pawn chain sits on determines their good bishop (the opposite coloured to that colour bishop is the good bishop) seek to trade their good bishop while keeping your good bishop, this is a minor advantage that becomes greater in the latter part of the game.
The first one to double rooks on a file usually owns that file for the rest of the game. There are notable exceptions and usually a great many tactics available to both sides when fighting for dominance over a file so be careful with this one!
A rook on the same file as an enemy king or queen (even if there are many pawns and minor pieces blocking) is still a valuable position for the rook, as you can usually create interesting tactical variations by removing the pieces in the way 1 by 1.
Look for "back-rank" problems in your opponent (as well as yourself!) If your king or your opponent's king can be mated with one rook attack on the back rank this makes for interesting tactical options for both sides!
Try to make your rooks "pigs." A pig rook is a rook placed on the second to back rank (either rank 7 or 2 if you are playing white or black.) A pig rook is very strong as he is usually both attacking undefended pawns as well as posing a considerable threat to the enemy king. If you can get doubled pig rooks this usually means a win or a draw for yourself. This is generally hard to accomplish as it takes a minimum of 2 moves (usually 4+), but look for tactics as this is almost always a win especially near end-game!
Rooks belong behind passed pawns, and always push your passed pawns, the closer they get to the other side the more they are worth!
The three (or four) pawns in front of a castled king are extremely important. Enticing your opponent to move them (to kick a bishop or a knight) creates a permanent weakness in your opponent's defences. Always give your opponent the option of kicking your piece with these pawns, as when he does you know that you can take advantage of the new weakness he has created.

With that last point, I would like to conclude this with two simple principles: the principle of two threats and the principle of every move leaves something behind. The first principle is easy to understand, create 2+ threats for your opponent and it will be hard or impossible for him to defend both. The second principle is much more subtle but just as important. Chess is a game of a delicate dynamic equilibrium. Every move you or your opponent makes gains some advantage but also creates some weakness, if ever so slight. Search for these weaknesses in yourself and in your opponent at all times.


Tiebreaks in the Baku Chess Olympiad How are tiebreaks calculated in the Baku Chess Olympiad?

For example, the US team took gold over Ukraine having scored 413.5 on tiebreaks vs 404.5. My gut instinct was to guess the Sonneborn-Berger score or team points, but 413.5 is too high for that. Is it some combination of the two?

The tie-break rules are listed on the FIDE website, D.II.02 paragraph G.14:

  The position of teams that finish with the same number of match points shall be determined by application of the following tie-breaking procedures in sequence ...

  (a) the sum of Sonneborn-Berger points, which are calculated as follows:
  match points of each opponent, excluding the opponent who scored the lowest number of match points, multiplied by the number of game points achieved against this opponent

So yeah, it's called Sonneborn-Berger, but it's different from the one you see in individual tournaments.

Let's see if this holds for the USA team:

GP  OPP MP   GP*MP

4   AND 10 (ignored)
3.5 SCO 12 = 42
3   ARG 14 = 42
2   CZE 14 = 28
3   SRB 13 = 39
2.5 UKR 20 = 50
3.5 IND 16 = 56
2   RUS 18 = 36
3   NOR 16 = 48
2.5 GEO 14 = 35
2.5 CAN 15 = 37.5
TOTAL:      413.5

We arrive at the same total.

(scores can be found here).


Rossolimo 3.Bb5 vs open Sicilian against c5-Nc6 sicilian Many chess players nowadays recommend the Rossolimo against c5-Nc6 Sicilian:

[fen ""]
1. e4 c5 2. Nf3 Nc6 3. Bb5

However, I find the open sicilian to be easier to play:

[fen ""]
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. Nd5 Be7 10. Bxf6 Bxf6 11. c4 b4 12. Nc2 a5 13. g3 O-O 14. Bg2

One of the reasons of my preference is that I have control over the d5 square and black has a backward pawn on d6. Moreover, I can play moves like Qd3,a3, and play on the queenside with my rooks too.

My issue with the Rossolimo is that it gives up the bishop pair for no obvious outpost for the knight like the second position in the open sicilian that I shared above.

I would really appreciate it if you can tell me why the Rossolimo might offer better winning chances with White, and why top players are attracted to it, and why Black players try to avoid it in their repertoire. Also, if you can refer me to good thematic games with Rossolimo.

Please note that the ...e5 push Black does on your line is not forced and there are plenty of other variations Black can opt for (like 4...e6, or 4...g6, or 4...Nf6 5.Nc3 d6, or even 4...e5)

Each of this alternatives requires White to be prepared as Black will probably know a lot of theory about those (and have a good understanding of the resulting middlegame positions, for instance, no d5 weak square in many of those) With the Rossolimo, White can opt for a quieter game where knowledge of precise lines is less relevant


Why is it common to castle right after the opponent castles? After watching many chess games, I've noticed that many players castle right after their opponent castles. Is this a coincidence? Or is there an unspoken benefit of this?

Edit: And by right after I also mean right before. I.e. games where both castling taking place one turn apart.

Castling is a certain 'committing' move; if you castle kingside, your king is stuck there until the late middlegame / early endgame, and you cannot easily launch a pawn storm on that side. The first allows your opponent to castle queenside and know he/she can launch a king attack (but possibly allowing your attack as well); the second allows your opponent to castle kingside and know his/her king is relatively safe.

Also, the castling move doesn't threaten anything (like capturing an undefended piece, or a fork), so if you castle, the opponent doesn't have to defend and has time to castle as well.

A final thing to note is that castling can occur as early as move 4, and really late (move 20 or later is not that uncommon), but in most games it happens between moves 6-12*. This makes the probability that both castling moves (if both players castle) happen right after each other much higher than if castling would happen throughout the entire game.

*: I'm just making an educated guess here; I'm very interested in the actual statistics.


List of plans or strategic themes I know of lists that cover tactical themes and endgame themes. I can't find a list of plans or strategic themes in the middlegame.

Could someone help me out with this list? A link would be nice.

Perhaps you can use the table of contents from classical works such as

Modern Chess Strategy, by Pachman, and

The Middlegame, by Euwe and Kramer.


Where is London Chess Classic Pool B's webpage? I don't now if here is a right place to ask this question. I think London Chess Classic has at least two different pools but I find only one of the pools in their website, is there any page which shows standings and games in the other pool(s)? Or it has only one pool? The main pool (or the only one) is the pool of super grandmasters. I'm also interested to watch weaker pool games and events. I know I can access the games from other websites like chessgames etc but it's strange if they do not associate any page to the other pool (or it's strange if there is no other pool then what is this?)

Here's how you can find the tournament results:

Link = Chess Results page

Use ctrl + F to locate Tournament selection

You'll then notice all the sections:

Super Rapidplay
FIDE Open
Weekend Open
Weekend U2000
Weekend U1800
Weekend U120
Weekday U2000
Weekday U135
English Junior Rapidplay

Hope this helps.


Is there an effective attack as white after Nf3 with e5 response in Atomic chess? I'm a typical player who enjoys the 1. Nf3 opening as white in Atomic chess games. Today in an online Atomic chess tournament, I come across a player who played the 1... e5 response. As 1... f6 is the typical response here, and 1... e5 doesn't protect the G5 square, 2. Ng5 could be played. But since 3. Ng7 allows the black queen to escape to E7, or even worse to H4 and threaten an explosion at F2 on 2... f5 2. Ng5 doesn't seem to lead to anything effective. What should be played next?

[FEN ""]
[White "Attacker"]
[Black "Defender"]
[Variant "Atomic"]

1. Nf3 e5?!

There is a very interesting website with opening theory from the very first moves of atomic chess :
https://www.unix-ag.uni-kl.de/~chess/atomic/

To answer your question, after :
1.Nf3 e5 ? 2.Cg5 f5 ! ( Qxg5 lose the queen and ...f6 3.Nf7 Qe7 4.Nd6+) 3.h4! (cover h4 square from the black queen) and then 3...c6 4.Nxh7! or 3....Bc5 4.d4 Bb6 5.Nf7 Qe7 6.Nd6 Kf8 7.Nxb7 both leads to massive destruction of Black camp.


Is the dead position problem solvable? In chess, there are some dead positions (FIDE Laws of Chess).

5.2.2 The game is drawn when a position has arisen in which neither player can checkmate the opponent’s king with any series of legal
moves. The game is said to end in a ‘dead position’. This immediately
ends the game, provided that the move producing the position was in
accordance with Article 3 and Articles 4.2 – 4.7

Arbiters or players will terminate the game OTB, but is it possible to have computer solutions for dead position detection? If it is, then how?

Computer detection of dead positions is much trickier than people think. It is unlikely that an algorithm exists that runs in reasonable time and is 100% accurate.

It is easy to check for a simple condition like insufficient material (K+B v K, K+N v K). It is less easy to check for cases with blocked pawns, for instance:

2b1k3/8/8/1p1p1p1p/1P1P1P1P/8/8/2B1K3 w - - 0 1

since there are a lot of legal moves to check. Computers aren't based on intuition like humans: you'd have to enumerate every single possible continuation for up to 150 ply without pawn moves/captures (those reset the counter) and check that none of them end up in checkmate for either side.

You could try other tricks, like trying to store the positions reached in a tree and checked that none of the reachable positions are mate. That's only 76176 positions for the example I gave, but you'd need to check that the tree is indeed exhaustive - i.e. every legal move in every position must be tried. That's not going to be efficient.

You could also try to invent some arbitrary heuristics to help your algorithm, like checking for blocked pawns and same coloured bishops. The problem with this approach is that sometimes the heuristics are wrong, or they aren't general enough. (Brian Tower's answer is an example of an attempted heuristic, but in the comments user17439 shows it fails to flag some dead positions and I show it incorrectly flags a non-dead position.)

And I would love to see any heuristic or algorithm that can distinguish between the following positions (problem by Andrew Buchanan, StrateGems 2002)

Dead:

Bb1k1b2/bKp1p1p1/1pP1P1P1/1P6/p5P1/P7/8/8 w - - 0 1

Alive:

Bb1k1b2/bKp1p1p1/1pP1P1P1/pP6/6P1/P7/8/8 w - - 0 1

The second position is alive since mate is possible after

1.Ka6 Ke8 2.Bb7 Kd8 3.Bc8 Ke8 4.Bd7+ Kd8 5.Be8 Kc8 6.Bf7 Kd8 7.Bg8 Ke8 8.Kb7 Kd8 9.g5 Ke8 10.Kc8 a4 11.Bf7#

In sum, I do not believe you can have an algorithm that is 100% accurate in distinguishing between dead and alive positions that runs in reasonable time. Brute force is the only 100% reliable method, but it is definitely not efficient. You can get a decent success rate for "practical" positions with heuristics, but it will not be 100% accurate, even for real game positions.


When to play h5 (or h4 with white) in fianchettoed position for black Imagine that we have this game
[FEN " "]
1.e4 c5 2. b4 cxb4 3. a3 bxa3 4. Bxa3 Nc6 5. Nf3 g6 6. d4 Bg7 7. h4

Do you play with Black in this case h5 or not? In my opinion, I rarely like to play h5 because it gives up the g5 square and white can plant his knight there. On the other hand, I feel like I stopped a barbaric attack temporarily. I would like to get some feedback about in which cases you think playing h5 is good defensively, and when it's bad and a concession. Not necessarily for the opening that I have mentioned above. Just in general.

I generally don't like accepting gambits as black on principle, so the position on your diagram feels already rather uncomfortable to me, but in general, there are a few typical ways to deal with h4-h5 if you have played g6 and your opponent replied with h4.

just ignore it; might be ok if you haven't castle yet. There, you're not afraid of hg hg, Rxh8 Bxh8, but you have to consider the consequences of h5-h6 harassing your bishop. You don't  usually want to play Bf8, as well as Rg8 vacating the h8 square, so you probably have to prepare Bf6 (if you can). Of more or less recent games, I saw it here: https://www.chessgames.com/perl/chessgame?gid=1926269. There is another line in Gruenfeld where black is doing this, but sorry, can't recall it now. Check Peter Svidler games w/ black if you're interested.
Indeed play h5, as you mentioned; I'd say the main danger here is not the g5 square per se (although it is also important) but whether white can play g2-g4 later, opening the files. So it depends on how strong you grip on the g4 square is. Sometimes white has already committed to f2-f4, and then I'd consider h7-h5 more seriously. Black does play this in dragon sometimes, thanks to his control of g4 with N on f6 and B on c8/d7.
just put a knight on f6 and take the pawn on h5. Depends whether white can easily chase this knight with e4-e5, so in this particular variation it is probably not so great. Also in Gruenfeld, after smth like 1. d4 Nf6 2. c4 g6 3. h4 Bg7 4. Nc3 d5 5. h5 black plays Nxh5, there was a Grischuk-Nepo game also from 2019 I suppose.
Another rather robust structure arises after h4 Bg4, h5 gxh5. If white knight is already on f3, it might be not so easy for him to get rid of the g4 bishop. Not an option here obviously. Can't think of an example to this unfortunately. If I remember the game I'll update it.
A more conservative way is probably to play h6, and meet h5 with g5. I have seen this in closed sicilian (or english with 1. c4 e5 with colors reversed); can't think of a top-level game, but this should do https://www.chessgames.com/perl/chessgame?gid=1214057. The danger here lies in the f4 attack or piece sac on g5, yet the latter is probably harmless if you haven't castled yet. In this particular variation I'd consider this to be my main idea as black. The downside of playing h6 might be that if white has a battery on the diagonal, for example, Be3 and Qd2, you could have trouble castling unless you play Ng4, so it is again important to control the g4 square.

In any of those options, if you give white enough time, he will break through whatever you choose, so you probably should aim not at closing the king side and stopping white's attack there forever but rather buying yourself a bit of time to prepare the counterattack in the center.


Does it ever make sense to stall for time? The game clock is used to prevent players from overly delaying the game (the keywords being "overly delaying the game"). Are there times in a timed game that stalling one's own development of the board makes sense, and if so, what would be the best example of this taking place?

In the bughouse variant a situation can definitely arise in which it makes sense to stall for time. If I'm facing checkmate next move on my board no matter what I do, then if my partner's opponent has less time on the clock than I do, I should just sit tight and hope that my partner can win on his board before my time runs out. (And if my partner's opponent has more time than I do in that situation, then he should just sit tight as well and force me to either accept mate or flag first.) But I realize you are actually asking about chess proper here, not bughouse.

I can't think of any scenario in which it makes objective sense, in terms of the game play, to stall for time, assuming you are talking about a situation in which: I already know what my next move is going to be (and have no intention of reviewing my decision any further), but I let my clock tick down instead of making my move immediately. But a player might have a psychological reason to stall at times.

In this interview (with accompanying videos in Russian) of grandmaster and noted commentator Sergey Shipov, conducted just recently during the ongoing world championship match, the topic arises as to the amount of time top players like Gelfand, Kramnik and Kasparov spend when making moves in positions that they've already analyzed during their home preparations. (See section "6. Kasparov puts on a show.") Shipov opines:

  For example, when, in Kazan, Gelfand thought for almost 40 minutes about one continuation in that game against Grischuk it later became clear that he’d looked at it all before. [17. Rd1 in game 6 of the candidates' final] ... he was considering some nuances, subtleties. He’d looked at the plan itself, but perhaps he was clarifying some of the concrete details. That depends greatly on the chess player. Kramnik won’t, for example, think for 20 minutes, never mind 40 minutes, about something he’s already looked at. He’ll play quickly. Kasparov, on the other hand, might do that. With Kasparov a position could be absolutely familiar to him but he’d think for 20 minutes, look at it, make various gestures, and it seemed to everyone that Kasparov was creating and coming up with something at the board. In actual fact, however, it was a one-man performance based around the creative process. (My emphasis)

Shipov doesn't indicate exactly what he thinks Kasparov's underlying motivation for this was supposed to be, but he is clearly suggesting that Kasparov wanted either his opponents or his spectators not to be sure when he was in his preparation and when he was extemporizing. So that's one possible answer.


Chess helps academic performance? Is there a study that tries to show that chess helps academic performance? How does chess help our academic performance? If any? Does playing chess make us smarter at school?

Start here: http://psmcd.net/otherfiles/BenefitsOfChessInEdScreen2.pdf

There are a number of reasons. Probably the most prosaic is that the brain is like every other muscle in your body, the more you use it the stronger it gets. Add to that the fact that chess gives you practice at breaking down a large goal into achievable steps (going from "Checkmate my opponent" to "First I need to get my pieces in position to attack, then I ...") and spatial reasoning ("A Bishop there will prevent his knight from attacking me here"). Add in teaching just a bit of empathy ("what move would I make if I were in my opponent's position") and it's a solid win all the way around.

The evidence shows that chess definitely improves performance in school. And recent research in Neuroplasticity indicates that learning chess can help an old brain stay limber longer, so there's even proven benefits for us Old Pharts(tm).


What are the consequences of an early a6 in the Sicilian? Once I encountered an opponent who used a very early a6 in his Sicilian Opening.

[FEN ""]

1. e4 c5 2. Nf3 a6

What could have been his objective with this move and how should I have have countered it?

This is called the O'Kelly variation of the Sicilian.

If white plays normally (i.e. 3.d4 cxd4 4.Nxd4 Nf6 5.Nc3), then black can eventually kick the d4 knight with ...e5 when the knight doesn't have any great squares.  In this case, 2... a6 keeps the knight from moving to the natural b5 square (as in the Sveshnikov Sicilian).  This will allow black to quickly play ...d5 with equality.

White's best plan is to play either c3 or c4 trying to prove that black's move 2... a6 is not a good developing move.  When white plays c3, the natural plan is to follow up with d4, and then if black plays ...cxd4, white will respond with cxd4, gaining a classical pawn center.  When white plays c4 instead, white's plan is to set up a Maroczy bind.

An unambitious plan for white would be to play into a closed Sicilian - in the closed Sicilian, black frequently plays a6-b5 in order to get counterplay on the queenside.  Furthermore, in the closed Sicilian, tempi matter a lot less because the position will not change radically from one move to the next.


Why is the French defence not played at the highest level? I am a French defence player and I enjoy playing almost all the lines (Tarrasch, Winawer, advance variation, ...) because I think the play that follows the opening suits my style and I feel very comfortable. I am a club player (~1800).

I have realized lately that at the very top level the French is not played. Most of the games that start with 1. e4 end up being Sicilian defences, Berlin Walls (or some other lines of the Ruy Lopez) or even some Caro-Kahn (I recall at least a game or two of Giri playing this).

If we don't consider just the very top level (which I consider to be the top 20 players in the world more or less) we can find some 2700 rated players who have played the French (I recall some game from Vallejo now).

So I wonder why is the French not played more often. Which is the line for white that gives the greatest advantage? Could anyone point me to a reference explaining how to "refute" the French with white?

Peter Svidler answered this in a recent video for Chess24:

  Why do the majority of GMs and almost all super-GMs play 1…e5 or 1…c5
  in answer to 1.e4 rather than the French Defence (1…e6)?

  Peter: I think the answer is twofold. Firstly, both the Spanish and
  the Sicilian offer you a much broader scope to choose from. If you
  play 1…e5 you’re not really limited to one structure, let alone one
  line. That’s not necessarily to say the French is one structure and
  one line, but it does limit Black’s opportunities more than the
  Spanish or the Sicilian. But I think the bigger issue with the French
  is, at least for me, that it was always a very, very difficult opening
  to understand. I didn’t do that badly in terms of practical results,
  but actually understanding what’s going on in the opening is another
  matter – even from the white side, and it’s generally accepted that
  the white side is the more comfortable side of the French Defence.

  That
  brings me to my second point. This was mainly to do with the fact that
  I played French games almost exclusively with Alexander Morozevich,
  who put a tremendous amount of work and imagination into building his
  French repertoire. If you do that it becomes a very attractive option
  against 1.e4, because people don’t encounter it that often these days.
  People are no longer very convinced with their choices and I think
  it’s very playable and also a very sharp opening that you could argue
  definitely gives you more counterchances than the Spanish. If the
  white player would prefer a quiet life he will find it harder to find
  a quiet life in the French than in the Spanish.


Can a grandmaster always draw? I was watching the Challengers championship recently and noticed that the commentators talking about Wesley So’s last game got annoyed that he was aiming for a draw and didn’t really have any fight in him.

A draw was agreed after only 20 odd moves, and that got me thinking - if a top grandmaster were to aim for a draw against AlphaZero for instance, would they always manage?
Can a Grandmaster force a draw?

No.  It may be difficult to win against a top GM who is playing for a draw, but it's by no means impossible.

If GM's could always draw at will, we could stop all championship matches once either player won a game, since the outcome would be decided.  But we don't do that, because the outcome is not decided after one player gets one win.


Converting square notation to algebraic notation programmatically I'm not sure if this is the right place to put this question, but it requires a fair amount of chess background so I decided to post it here.

Square notation describes moves by simply noting the square the piece moved from to the square the piece moved to. For example, e4 is e2-e4 and Nf3 is g1-f3.

Algebraic notation is far more common and is well-handled by most chess libraries.

Does anyone have any background working with the conversion between the two?

To do what you want, you'll need a move validator. To make things clear, let's take a look at the Stockfish iOS chess playing app. The app uses the Stockfish chess engine. The outputs from the engine would be something like:

e2e4 e7e5 ...

But that's not what we want to see. We'd need to convert the outputs to something like:

1. e4 e5

How do we do it? The open-source Stockfish app has a function called move_to_san defined. Please download the full source code from the Stockfish web site. Here, we'll briefly go through the implementation.

const std::string move_to_san(Position &pos, Move m)

This is the header of the function. It takes a position object and a move. That's why I asked you whether you have a move validator implemented. You'll need a validator for this position object as we will see.

from = move_from(m);
to = move_to(m);
pc = pos.piece_on(move_from(m));

Here, we grab the source and destination square. We also need the moving piece.

else if(move_is_long_castle(m)
      || (int(to - from) == -2 && type_of_piece(pc) == KING))
    str = "O-O-O";
else if(move_is_short_castle(m)
      || (int(to - from) == 2 && type_of_piece(pc) == KING))
str = "O-O";

Next, we check if the move is a castle move. Note that it's a good idea to store the move as "e1 to h1". This is not what we normally expect, we always do move the e1 king to the g1 square then the h1 rook to the f1 square. The conditions in the code take care of that.

str = "";

if(type_of_piece(pc) == PAWN) {
  if(pos.move_is_capture(m))
    str += file_to_char(square_file(move_from(m)));
}

This is starting to get interesting. We build an empty buffer. Once we've done it, we'd need to ask if this is a pawn move. If it's a pawn move, convert it to an ASCI character. If our move is e2e4, the buffer would have been "e" by now.

  str += piece_type_to_char(type_of_piece(pc), true);

If this is not a pawn move, we convert the piece to a character. This can be done by a dictionary if you prefer.

if(pos.move_is_capture(m))
  str += "x";

str += square_to_string(move_to(m));

Next, if it's a capture, we add an "x" to it. Then, we'll need to add the destination square.

if(move_promotion(m)) {
  str += "=";
  str += piece_type_to_char(move_promotion(m), true);
}

Promotion.

pos.do_move(m, u);
if(pos.is_check())
    str += pos.is_mate()? "#" : "+";
pos.undo_move(m, u);

Is this a check?

What have we learnt so far?

We need an internal board representation. For example, the code pos.do_move(m, u) needs a mechanism to save the board. You can implement a bitboard, a mailbox or an object-oriented design.
We need a way to tell where the move comes from, where it goes to etc. This can be done by simple logical operations.

Please download the Stockfish iOS source code. Study the code. You can post a new question if you're not sure what to do with the code and I'll help you.

Everything here is in C++. You might need to port the code to Ruby.


What to do in an opening trap In light of the recent game Nakamura vs Anand, the second time, in the recent candidate's tournament, Anand fell into Nakamura's opening preparation trap out of the reversed sicilian.

If he [Anand] had realized that he was falling into an opening trap, or opening preparation, is there any possible thing that he could have done to avoid his loss?

I ask this question to better understand how to respond to obvious opening traps out of really obscure lines, and even traps out of reasonable looking lines.

As I see it, at that level they have two options, if they suspect their opponent prepared a trap:

They trust their preparation, and their knowledge, go on as usual, and just make the best moves, and hope for the best. In the Sinquefield cup last year, or the year before, there was a game MVL-Carlsen, when this happened exactly, Carlsen was caught by MVL-s preparation, and after few moves, he found an intresting, very human move, that the engine weren't suggesting, and now MVL was fighting for survival. It was a scotch game I think, it ended in a draw, but worth to watch.
They decide to not take risk, and just chose a sideline, where maybe the other one has an edge, but they can outplay him. Tal writes in 'The life and games of M.T.' about a lot of situations like that, when he choose a sideline, because he was suspecting for some reason that his opponent prepared a suprise.


Are there known opening gambit lines for black in the French defence? I play the French defence with both colours (white and black) and generally play any of the orthodox main line openings (there are many eg Advance, Exchange, Classical,Tarrasch etc giving rise to many variations as openings and defence variation eg early ...Qb6 Wade var.).

There are some gambit openings from the White side and as white I often play the Milner-Barry Gambit and have started to reacquaint myself with the Alapin-Diemer (I sometimes face the MBG as black). So far though I have not encountered a gambit line for the black side in the French and so wonder if there are any such playable black French gambit opening lines?

If anyone knows one or more I'd be interested to hear.
I look forward to replies and comments, but meanwhile I will keep searching myself to find such a gambit for black in the French defence opening.....

There's the Poisoned Pawn variation of the Winawer:

[fen ""]

1. e4 e6
2. d4 d5
3. Nc3 Bb4
4. e5 c5
5. a3 Bxc3+
6. bxc3 Ne7
7. Qg4 Qc7
8. Qxg7 Rg8
9. Qxh7 cxd4

In general, though, it's hard to find a good pawn for Black to give away in the French.


Identifying principles and thought processes to use in locating a +3.2 or similar move [Title "indrekaavik-Swifty15, chess.com, 5/3/2021"]
[FEN ""]
[startply "29"]

1. e4 c6 2. d4 d5 3. e5 Bf5 4. Nf3 e6 5. h3 c5 6. c4 Nc6 7. cxd5 exd5 8. Bb5 Qa5+ 9. Nc3 cxd4 10. Nxd4 Bd7 11. O-O Nxd4 12. Qxd4 Bxb5 13. Qxd5 a6 14. Rd1 Rd8 Qf3 Ne7 16. Bd2 Ng6 17. Qxb7 Nxe5 18. Nxb5 Rxd2 19. Qb8+ Qd8 20. Qxe5+ Be7 Rxd2 Qxd2 22. Nc7+ Kf8 23. Nd5 Qg5 24. Qb8+ Bd8 25. Rd1 g6 26. g3 Kg7 27. h4 Qh5 28. Nf4 Qxd1+ 29. Kh2 Bxh4 30. Qe5+ Bf6 31. Qe4 Qf1 32. Nh3 h5 33. Qb7 h4 Qb3 hxg3+ 35. Qxg3 Qe1 36. Kg2 Qe4+ 37. Kf1 Bxb2 38. Nf4 Qb1+ 39. Ke2 Rh1 Nd3 Qd1+ 41. Ke3 Re1+ 42. Nxe1 Qxe1+ 43. Kf4 Qb4+ 44. Kf3 Qc3+ 45. Kg2 Qxg3+ Kxg3 Bd4 47. Kf3 f5 48. a3 g5 49. a4 g4+ 50. Kf4 Be5+ 51. Kxf5 g3 52. fxg3

I'd like to improve my thought process when considering a move, but I don't understand what rules/principles to apply to a particular situation where I got it wrong. This happened in the above game I played as black on chess.com. I am aware that I made plenty of mistakes before and after the move, but those I understand. I am rated 1200.
I discounted the rook exchange 15... Rxd1. After the game, the engine told me I would have had a +3.2 advantage if I had made the exchange. I can't work out why it creates that advantage.
I considered the exchange, but I thought I would stay disciplined and principled. I remembered GM Smirnov's rule "to take is a mistake. I have been reading in IM Silman's '"The Amateur Mind." It teaches that a simple one-move capture, attack, or check is pointless if it can be easily parried.
My thinking was that exchanging rooks MIGHT be useful if I gained a tempo by sending my opponent's knight to the back rank. But I saw when that they could just recapture with their queen and take control of the d file. It didn't seem that I had anything to gain. As such, I just continued to develop my pieces.
Can anyone explain why this was such a critical move, and the thought processes I could have used to identify it?

This position is more complicated than it first looks!  You need to see more than one move deep to understand the difference between 15...Rxd1 and other moves.
As Scounged has pointed out, you already have an advantage of about +3 because you're a piece up.  The problem is that white is attacking your pawn on b7.  So some time soon, you want to play a move like ...Bc6 to defend that pawn.  In fact, if you play ...Bc6 right away, it's almost as good as ...Rxd1.  But the computer thinks it's even better to play 15...Rxd1+ 16. Qxd1 Bc6.
With your chosen move, white missed an opportunity.
Option 1: 15...Ne7 16.  Qxb7 doesn't work for white, because of 16...Rxd1+ 17. Nxd1 Qe1+ winning the knight.
Option 2: 15...Ne7 16. Rxd8+ Qxd8 17. Qxb7, and now white has two pawns in exchange for the bishop, and the game is almost on equal terms (black is still ahead, but it's not as good as if you'd played 15...Rxd1).
Suggestion: if you don't already know the word "zwischenzug", look it up and think about how it relates to this position. Sometimes the engine isn't really telling you about the next move, but pointing out something further along the sequence.


What openings are recommendable for beginners to study? I am a beginner. With reference to opening theory, which opening should I start learning?

My friends are suggesting Ruy Lopez...

To answer your question directly, your friends aren't wrong, and it's not a bad idea at all for you to play the Ruy Lopez, from both the white side and the black side. In fact, knowing nothing much about you or your exact level of play, it's still a safe suggestion that opening with either 1. e4 or 1. d4 with white, and responding with 1. e4 e5 or 1. d4 d5 with black is a solid way to begin to get your footing in the opening phase of the game. Of course, that's just move one (and only the two most popular options for that), and there are plenty of forks in the road beyond that point. Nevertheless, while my advice to you is that playing the Ruy Lopez is a great idea, studying it (or any other opening) in any great depth is not, at least not right now.

Instead, you should focus on a few principles, like aiming to get your king safely castled in a timely manner, trying to control the center of the board with your pawns (our first moves above are a good start), and developing your pieces with the idea of using them to further control the center of the board. All of these ideas are visible in the Ruy Lopez, and that's one reason it is a good suggestion. After 1. e4 e5, we see that 2. Nf3 develops a kingside piece and helps control the central squares d4 and e5, 2. ... Nc6 fights for control of those same squares (and defends the e5 pawn), and 3. Bb5 indirectly fights for those same squares by threatening the c6 knight, while also clearing the path for the white king to castle. Part of my point is that all of these moves make a great deal of sense, just for the principled reasons given here, and can be recognized as such and played confidently without needing to get your hands dirty with a lot of opening theory.

To learn more about important opening principles, and what you should be thinking about in the opening phase of the game, you might consider checking out John Emms' book Discovering Chess Principles: Building Opening Skills from Basic Principles, which is aimed squarely at developing in beginners a good sense of how to make good moves in the opening. (You'll find good reader reviews at that link; for good measure, here's a review from Chessville as well.) In addition to that, I'd say what's most important is just to play a lot and have fun, keeping guiding principles in mind while you do, and when things do go wrong, make a point of determining why. Try to figure it out yourself, and any time you can't, seek out an explanation from someone else. (Maybe come back here and ask!)


The Evolution of the K-Factor The change in Elo ratings depends, among other things, on the K-factor (or development coefficient).

Current rules

FIDE Rating Regulations effective from 1 July 2017 give the following values:

K = 40 for a player new to the rating list until he has completed events with at least 30 games; and for all players until their 18th birthday, as long as their rating remains under 2300.
K = 20 as long as a player's rating remains under 2400.
K = 10 once a player's published rating has reached 2400 and remains
at that level subsequently, even if the rating drops below 2400.

The same values have been in effect since July 1, 2014.

Past rules

The Wikipedia page on the Elo rating mentions that FIDE used the following values before July 2014:

K = 30 (was 25), for a player new to the rating list until the completion of events with a total of 30 games.
K = 15, for players with a rating always under 2400.
K = 10, for players with any published rating of at least 2400 and at least 30 games played in previous events. Thereafter it remains permanently at 10.

My questions

When were these past rules enforced?
When was the change from K=25 to K=30 applied?
With the exception of this last change, have these values been applied since the beginning of Elo's creation?

I take the liberty of asking all these questions at once because they're related.

The USCF implemented Elo's suggestions in 1960, and the system quickly gained recognition as being both fairer and more accurate than the Harkness rating system. Elo's system was adopted by the World Chess Federation (FIDE) in 1970. Fide used k=30 factor before July 2014.


Why does Stockfish recommend this bishop exchange early on? When reviewing my games on Lichess, I very often find the Lichess engine recommending to me to sacrifice the bishop early on after checking the enemy king. I have created a sample game where you can see it happening. I don't see myself in any better position there, so I am curious what I gain by doing this.
[FEN ""]

1. e4 c5 2. Nf3 Nc6 3. c4 Nd4 4. Nxd4 cxd4 5. d3 e5 6. Be2 Bb4+ 7. Bd2 Bxd2+ 8. Qxd2

I just don't understand why it wants me to move my bishop to b4 in the first place. I'd much rather want to develop my position more by doing c5 or knight f6 or similar.

I wouldn't say it was a "sacrifice", it was more like an exchange of bishops.
My lichess engine was actually giving me ...Bd6 as the first move.

I don't understand why it wants me to move my bishop to b4 in the first place

Me neither. I doubt anyone here will have an idea. Stockfish doesn't tell us why. If I have to make a guess, I would say the bishop is being blocked by the d4-e5 pawn chain, so it makes sense to exchange the bad bishop off.


Does any country have as many GM's per capita as Armenia? Does any country have as many GM's per capita as Armenia?

If not which country is the closest? What are the some of the reasons for Armenian success in the chess world with its relatively small population?

Are there best practices from chess education in Armenia that can be utilized in other countries hoping to raise more strong Grandmasters?

It's from 2010 but you might look at

http://pogonina.com/index.php?option=com_content&task=view&id=154

where as expected Iceland is number 1, and Armenia is number 3. Number 2 might surprise you!


FICS rating vs FIDE Elo I know that is hard to establish an exact equivalent, but I was wondering what is the factor P in this equation: FICS_BLITZ_ELO * P = FIDE_ELO following personal experience. I mean, if you use to play FICS blitz games and have FIDE ELO, what is your P? I suppose that with a full hand of replies we can get an idea of P value.

In this case, I will have to quote from the FICS FAQ (http://www.freechess.org/Help/HelpFiles/fics_faq.html):

  39.My rating is over/under inflated.

  Don't worry!  Ratings are all relative anyway, not absolute. Compare your
      FICS rating only to other FICS players, not to ratings from other groups.
      Comparing your rating on FICS to a person's rating on another server or
      in a chess federation is not a valid comparison. FICS has a different
      rating system and a different player community than other organizations.
      Therefore your rating here is unlikely to match your rating somewhere
      else.

  40.I have a rating on FICS. What would my rating from in-person tournaments be?

  Ratings on FICS are not comparable to those gained from
      real life tournaments because they measure play against a different group
      of people under different playing conditions. Some users have higher
      ratings in real life, some have lower ratings.

In your question, you say FICS Elo rating, but the Elo rating system (http://en.wikipedia.org/wiki/Elo_rating_system) is a system of its own and FICS might not even be using it for its ratings. FIDE does, for sure! Also, comparing two rating systems is dubious since the opponents you meet, the time controls you use and the initial rating you get and the rating system you use will differ! But comparing the FIDE blitz rating with the FICS rating might be more valid. In this case, my guess would be that the FICS rating will be higher than the FIDE blitz rating. And I base this on absolutely nothing!


Is there any database of every position ever played in a recorded game? Is there any database of every position ever played in a recorded game? I don't ask of every possible position in chess, or "solving" chess. Only the positions that were played in a recorded game. Ideally, i would like to find for a position how many times it has been recorded to have been played and who won.

Is there any database of every position ever played in a recorded game

No database is perfect. I would say no for your question.

Sounds like you're looking for the most complete database? I propose:

Purchase Chessbase Mega Database (many games already!)
Data mine www.chessgames.com and https://www.365chess.com (you may need a script)
Download all TWIC games
Download lichess games
Download FICS games
Download MillionBase database

Perform an union operation on all those games.


strongest chess engine Can somebody tell me where can i find an updated list of the strongest chess engines. I want to find out a comparison (ordered list of engines)

Information on wiki http://en.wikipedia.org/wiki/Chess_engine is very outdated.
Typing strongest chess engine in google either gives links for 2011 year pages or to the sites of an engine with ads that it is the best. Sometimes I see tests done by random people on the laptop with a lot of fuss.

So it looks strange to me that I can not encounter official results.

The information on the Wikipedia page seems pretty up-to-date to me. I will retype a couple of the links from it.

The CCRL 40/40 list runs programs at the time control of 40 moves in 40 minutes.
The CEGT 40/120 list runs programs at the time control of 40 moves in 120 minutes.

There are four other links in the Rating List table from that Wikipedia link that may be worth exploring, though they seem to run at shorter time controls or with a smaller list of engines.

Pretty much every rating list that includes Houdini has it in the top spot.


When is it appropriate to use a program during games with a longer timeframe, such as correspondence chess? Are there rules about when a player may use a chess engine to aid his game?  Is it always frowned upon?  Do you have to specially ask?  Not that you can stop your opponent from using an engine, but is it cheating, or is it ever acceptable?  Thinking about it, I'm not sure what the point of two players using engines would be.

If you haven't agreed before the game then you should assume that it's not allowed. It will usually be regarded as cheating. If you wish to use a computer you should ask your opponent before you do so.

Playing with the assistance of a computer is sometimes called Advanced Chess. If you agree before hand that it's allowed, then there's no problem and both can use a computer freely. Some Advanced Chess tournaments are also played with standard time controls.

  Thinking about it, I'm not sure what the point of two players using engines would be.

The point of Advanced Chess is that a computer is strong at fast and accurate calculation but weak at strategy, while the human is stronger at strategy but more prone to errors in complex tactic situations. The human can use their strategic ability to guide the computer into strong strategical positions or won end game positions, while the computer can check that there are no blunders that the human may have missed. If played well, the playing strength of the human-computer team can be higher than each individual playing alone.


What are the most instructive Zurich 1953 games? I'm a club player that never really figured out the importance of studying master games. Since I want to improve my middlegame understanding I read that Bronstein's Zurich 1953 is an excellent place to start. However, going through the games takes 1-2 hours/each and I was wondering if some games illustrate the key concepts better than the other.

There are of course classics like the Averbakh-Kotov game.

But generally you get out of chess study, what you put into chess study. So you should play through games that interest and fascinate you. It should be fun, not something were you try to minimise the time spent from the outset.

For me, that meant for a long time wild tactical games. I played for example through the games in Bronstein's "Sorcerer's Apprentice", Tal's "My Life and Games", Christiansen's "Storming the Barricades" and Aagaard's "Attacking Manual".

I do own Zürich '53, but I don't think I ever spent much time on it.

But if you already own the book and want to proceed, I would recommend restricting yourself to well annotated, decisive games that feature openings from your repertoire.


What is the strategic significance of the English Opening? I enjoy playing the English opening, pushing my pawn to c4, and trying to out flank my opponent.  But I have a hard time, outside of playing normal lines, understanding the advantage it gives, and why it leads to fantastic games.  Any insights?

Since I was playing the English myself, I can tell you why I have found it a good opening for me:

Transpositional potential of this opening is stunning! You can lead your opponent out of his/her opening and draw them into the variations they do not know. One small example: 1.c4 c6 Since Black reveals to us that he plans to play Slav/Semi-Slav/Queen's Gambit we can steer the game into Caro-Kann with 2.e4!?. Now, this means nothing objectively--we just left one opening to enter into another--but the psychological effect can be devastating! It can lead to such consequences like deflating their will to play the game since the game is "boring", or you can actually transpose into an opening your opponent does not know and quickly demolish him.
The center remains fluid for a long time. This is truly gold in the hands of the experienced player and answers this part of your question:

  why it leads to fantastic games?

You see, since White restrains himself in the center, it is usually safe to play on the wings. Black usually responds by playing on the wings too, but inexperienced players forget about counter attack in the center. This possibility requires good calculation and accurate evaluation of the current position in order for a player to be able to execute this properly. Action on one wing + counter-attack in the center = crazy game. Launch your counter-attack in the center at the proper moment and you will win the game most of the time.

These are the beauties of this opening:

Its intolerance for "robotic play" and opening memorization--it requires of a player true knowledge. You must know how to play chess--opening, middle game and end game--no opening book can save you if you do not know how to play chess.
Its main feature is to give so much space to a "true" player for creating winning chances. If you are creative enough you can win in the opening, middle game and even an endgame. By "true" player I mean player who plays every game with 100% of his strength. The player who plays with knowledge and does not rely on safe patterns/30+ memorized opening moves and so on. The player who is willing to fight for victory to the very end.

Whether you play "normal" lines, or you play some side-line/transposition, the English opening will never be dull and sterile for a player who is prepared to invest all of his mental capacity to win the game.

Hopefully this answer will help you.

If you have further questions leave a comment.

Best regards.


Has a highly-rated GM ever lost to a low-rated opponent who didn't go on to become a GM? Has a highly-rated GM ever lost to a low-rated opponent who didn't go on to become a GM?

Also, currently has there ever been a GM who lost to low-rated opponents on a consistent basis?

There is a book called "Great Chess Upsets" by Reshevsky, but unfortunately most of the games are not upsets at all, but one famous player against another. Reshevsky himself, in his first major tournament, beat Janowski even though he was prepubescent. Prior to the tournament Janowski bitterly complained to the organizers that they were spoiling the gravity of the event by allowing children to play in it. After he won, Reshevsky reporting starting jumping up and down shouting, "I beat a grandmaster! I beat a grandmaster!".

Some of the more notable upsets:

In 1905 Frank Marshall, a World Championship candidate, lost to the unknown Dutch player Dirk Bleijkmanns at the Scheveningen Masters Tournament.

Joel Fridlizius beating both Alekhine and Spielmann at the Nordic Masters Tournament in 1912.

At the great St. Petersburg Tournament of 1914, the winner, Alexander Alekhine lost to German lesser light Bernhard Gregory.

In the 1923 Scheveningen Match Tournament, Spielmann lost to the little known Dutch master George Fontein.

In the 1924 Masters Tournament in Merano, Rubinstein lost to unknown player Gyula Patay.

Max Euwe lost to Vera Menchik at the 1930 Hastings Tournament, thereby becoming a member of the "Menchik Club".

The Cuban master Guillermo Estevez Morales beat Mikhail Tal after Tal blundered the exchange.

Croatian master Josip Rukavina beat Korchnoi at the 1973 Interzonal.

The unknown Ecuadorian player César Muñoz beat Bobby Fischer at the 1960 Leipzig Olympiad.

Bernardo Wexler beat Fischer at the 1960 Buenos Aires tournament.

An unknown player named Robert Burger beat Bobby Fischer in 12 moves in a simul after Fischer fell into a surprising trap of the queen.

Israeli Alexander Huzman beat Kasparov in the 2003 European Clubs Cup in 24 moves after Kasparov blundered two pawns because he missed a mate threat.


Carlsen-Anand, game 8 -> how can Black repel 25.Rc7? Instead of 25.Rfc1 as played in the game, why not 25.Rc7 to try for slight advantage or small initiative ( Ne5 could follow or trying to bring other rook to the seventh rank... )?

[White "Anand, Vishwanathan"]
[Black "Carlsen, Magnus"]
[Event "WCC 2014"]
[fen ""]
[Result "1/2-1/2"]

1.d4 Nf6 2.c4 e6 3.Nf3 d5 4.Nc3 Be7 5.Bf4 O-O 6.e3 c5 7.dxc5 Bxc5 8.a3 Nc6 9.Qc2 Re8 10.Bg5 Be7 11.Rd1 Qa5 12.Bd3 h6 13.Bh4 dxc4 14.Bxc4 a6 15.O-O b5 16.Ba2 Bb7 17.Bb1 Rad8 18.Bxf6 Bxf6 19.Ne4 Be7 20.Nc5 Bxc5 21.Qxc5 b4 22.Rc1 bxa3 23.bxa3 Qxc5 24.Rxc5 Ne7 25.Rfc1 Rc8 26.Bd3 Red8 27.Rxc8 Rxc8 28.Rxc8+ Nxc8 29.Nd2 Nb6 30.Nb3 Nd7 31.Na5 Bc8 32.Kf1 Kf8 33.Ke1 Ke7 34.Kd2 Kd6 35.Kc3 Ne5 36.Be2 Kc5 37.f4 Nc6 38.Nxc6 Kxc6 39.Kd4 f6 40.e4 Kd6 41.e5+  1/2-1/2

It is definitely worth considering, and probably an equally good move, but unfortunately it only leads to a similar simplification of the position (rather quickly), so Rc7 wouldn't really give an edge because black is well prepared to face it, as Ne7 prepares it. Either black replies by 25.Rc7 Bc6, locking the rook in to force the exchange, e.g. 26.Nd4 is just met by Rc8. Alternatively black can just exchange on f3, and play for minor activity himself, e.g. Nd5 or Rd2 after gxf3. (not necessarily a desired double-pawn structure for white either). Instead Anand went for activating his other rook and double his c-file, but black is just prepared enough to challenge it with an immediate Rc8, so long story short, the position just doesn't have much left in it to play for.

[White "Anand, Vishwanathan"]
[Black "Carlsen, Magnus"]
[Event "WCC 2014"]
[fen ""]
[Result "1/2-1/2"]

1.d4 Nf6 2.c4 e6 3.Nf3 d5 4.Nc3 Be7 5.Bf4 O-O 6.e3 c5 7.dxc5 Bxc5 8.a3 Nc6 9.Qc2 Re8 10.Bg5 Be7 11.Rd1 Qa5 12.Bd3 h6 13.Bh4 dxc4 14.Bxc4 a6 15.O-O b5 16.Ba2 Bb7 17.Bb1 Rad8 18.Bxf6 Bxf6 19.Ne4 Be7 20.Nc5 Bxc5 21.Qxc5 b4 22.Rc1 bxa3 23.bxa3 Qxc5 24.Rxc5 Ne7 25.Rc7 Bc6 (25...Bxf3 26.gxf3 Rc8 27.Rfc1 Red8 28.Be4 a5 29.f4 Kf8) 26.Nd4 Rc8 27.Rxc8 Rxc8 (27.Ra7 Bd5) 28.Rc1 Bb7


openings for white which don't involve a central pawn push It appears that black has more choices with regard to openings rather than white. While white would typically start with either e4 or d4, or sometimes c4, black has numerous choices for each of these openings. So a black player has a greater chance to out-prepare his opponent. I would like to know about openings white can play which don't involve a central pawn push, but which are nevertheless solid. This can take the black player out of his preparation. I do play the KIA (King's Indian Attack) sometimes. I don't really like the Reti so much though. Any other suggestions?

Since, you're already familiar with the King's Indian Attack and are looking for a solid line, I recommend playing the Nimzowitsch Larsen Attack, by first playing 1. Nf3.

Normally, the Larsen Attack starts directly with 1. b3, but after 1...e5, I wouldn't describe the resulting positions as "solid" for White, but rather more "dynamic".

  [FEN "rnbqkbnr/pppppppp/8/8/8/8/PPPPPPPP/RNBQKBNR w KQkq - 0 1"]

  1. b3 e5 2. Bb2 Nc6 3. e3 Nf6 4. Nf3 (4. Bb5 Bd6 5. Na3 $5 Na5 $5)
 (4. c4 d5 5. cxd5 Nxd5) (4. d4 exd4 5. exd4 d5) 4... e4 5. Nd4 Nxd4 6. Bxd4 Be7 *

1. Nf3 avoids the 1...e5 line, while at the same time maintaining the flexibility of transposing either into the King's Indian Attack or the Nimzowitsch Larsen Attack.

You can get positions similar to the Colle System (very solid and easy opening for White to play, without needing much preparation). Here, I give some sample lines where you can play the Nimzowitsch Larsen attack (often transposing to Colle), or, if you don't prefer certain types of positions, transposing back to King's Indian Attack (although rare).

     [FEN "rnbqkbnr/pppppppp/8/8/8/8/PPPPPPPP/RNBQKBNR w KQkq - 0 1"]

     1. Nf3 Nf6 (1... g6 2. e4 c5 3. d3 Nc6 4. g3 Bg7 5. Bg2 e6 6. O-O) (1... c5 2.
     b3 d5 3. e3 Nc6 4. Bb2 Bg4 (4... a6 5. d4 Nf6 6. Bd3) 5. Be2 (5. h3 Bxf3 6.
     Qxf3 a6 7. d4 e6 8. Nd2 Nf6 9. Bd3 cxd4 (9... Nb4 10. dxc5 Bxc5 11. O-O) 10.
     exd4 Nb4 11. O-O Nxd3 12. Qxd3) 5... Nf6 6. O-O e6 7. c4 (7. d4 cxd4 8. exd4
     Bd6 9. Nbd2 O-O 10. c4) (7. Ne5 Bxe2 8. Qxe2 Nxe5 9. Bxe5 Be7 10. c4 O-O 11. d3
     ) 7... Be7 (7... d4 8. Nxd4) 8. cxd5 Qxd5 9. Nc3 Qd7 10. Na4 b6 (10... O-O 11.
     Bxf6) 11. d4 cxd4 12. Nxd4 Bxe2 13. Qxe2) (1... d6 2. d4 Bg4 3. Nbd2 Nd7 4. h3
     Bh5 5. b3 Ngf6 6. Bb2) (1... d5 2. b3 Nf6 (2... Bg4 3. Bb2 (3. Ne5 $5 Bh5 4. d4
     Nd7 5. Nd3 e6 6. Nf4 Bg4 7. h3 Bf5 8. e3 Ngf6 9. Bd3 Bxd3 10. Nxd3 Bd6) 3...
     Bxf3 4. exf3 e6 5. g3 Nf6 6. f4 Be7 7. Bg2) 3. Bb2 Bg4 4. e3) 2. b3 d5 (2... d6
     3. d4 g6 4. Bb2 Bg7 5. e3 O-O 6. c4) (2... g6 3. Bb2 Bg7 4. e3 (4. g3 $5) 4...
     d5 5. d4 O-O 6. Nbd2 Bf5 7. Bd3) 3. Bb2 e6 (3... Bg4 4. e3 e6 5. h3 Bh5 6. c4
     c6 7. Be2 Nbd7 8. O-O Bd6 9. d4) 4. e3 c5 5. d4 Nc6 6. Bd3

EDIT:

This is a funny yet practical suggestion. If you really want to take the Black players out of their preparation, then why not try Anderssen's opening? (lol)

     [FEN "rnbqkbnr/pppppppp/8/8/8/8/PPPPPPPP/RNBQKBNR w KQkq - 0 1"]

     1.a3!?

Indeed the great Anderssen himself, in his match with Morphy (the greatest player of that era), tried this opening and scored one win, one loss and one draw, which is not a bad result at all against a player of Morphy's caliber.

Objectively speaking, the opening doesn't offer White any advantage, but it doesn't make White's position worse either. White essentially plays as Black, as though Black had played an extra move 1...a6. As you know, the move 1...a6 is quite useful in openings like the Ruy Lopez, Najdorf Sicilian, Benoni, Benko Gambit, Slav, etc. White's aim therefore is to play as Black and try to get into these type of positions to make sense of the move 1.a3. Practically, this move is worth a try if you want to disrupt Black's preparation or like playing certain positions as Black where 1...a6 is useful.

I give some sample lines where White tries to get into the desired positions mentioned above.

      [FEN "rnbqkbnr/pppppppp/8/8/8/8/PPPPPPPP/RNBQKBNR w KQkq - 0 1"]

      1. a3 d5 (1... c5 2. c3 (2. b4 $5 cxb4 3. e4) 2... d5 3. d4 e6 (3... Nc6 4.
      dxc5 $1) 4. Nf3) (1... Nf6 2. Nf3 d5 3. e3 g6 4. c4) (1... e5 2. c4 Nf6 3. d3
      Nc6 4. Nf3 d5 5. cxd5 Nxd5 6. e4) 2. Nf3 Nf6 3. e3 c5 4. c4 d4 5. b4 *


Why is Apronus allowing the White king to castle through an attacked square? I was using Apronus to make a new chess puzzle for Puzzling Stack Exchange, but then it did something odd.
[FEN ""]

1. Nh3 f5 2. e4 fxe4 3. d3 exd3 4. Be2 Kf7 5. Qd2 dxe2 6. O-O

It's letting the White king castle through a square that is attacked by a Black pawn-that is an illegal move! One should know that our replayer is not built to detect checks and whatnot, so I am able to show it here just fine. However, just shouldn’t be happening in a properly built PGN editor, which Apronus is.
Does anyone have any idea why this is happening?

I happen to be the author of the chessboard editor under discussion. Let me clarify the issue.

This editor is supposed to enforce legal moves but it has a bug which prevents it from being able to make a pawn capture onto the final rank. Therefore it cannot notice that a black chessman controls the f1 square. If you place a black bishop on the a6-f1 diagonal then it won't allow White to castle.

There is a newer chessboard editor that is free from this bug: https://www.apronus.com/chess/puzzle/editor.php?editpuzzle=0, which is meant as a powerful puzzle editor but it can serve as a PGN editor, too.

The "position setup" interface can be used to illustrate an arbitrary sequence of chessboards, not necessarily legal or illegal moves. If you tick the checkbox "Animation sequence" you will see that it keeps a record of all board positions like frames in a movie. It allows you to delete certain frames which effectively allows you to set up an arbitrary sequence of board position and generate an animated GIF diagram. I am the author of this tool.


Maximum number of pieces on board in dead position It is possible in a chess game to have a dead position in which both players have all eight pawns, one bishop, and a king--20 pieces total.  If the two players' pawns are interlocked in "zig-zag" fashion and each player's bishop is the same color as his pawns, each player's army will be forever stuck behind his own wall of pawns, with no way to ever reach anything on the other side.

[FEN "4kb2/8/1p1p5/pPpPp1p1/P1P1PpPp/5P1P/8/4KB2 w - - 0 1"]

What is the largest number of pieces that can be on the board in a legally-reachable position such that either:

The side on move has at least one legal move, but no sequence of legal moves would produce checkmate.
It would be possible to play an arbitrary number of legal moves, but no sequence of legal moves would produce checkmate.
No legal sequence of legal moves would produce checkmate or stalemate.

I would guess that the first of those might be possible with as many as 28 pieces on the board, but most escape-proof positions rely upon immobilized kings to block opposing pawns, making it hard to allow anything other than pawns to move safely.  What are the actual limits?

I've come up with 23, in the following position, with promotions:

[Event "?"]
[Site "?"]
[Date "????.??.??"]
[Round "?"]
[White "?"]
[Black "?"]
[Result "*"]
[FEN "nb2k3/2p5/1pP5/1Pp5/2P1p1p1/3pPpPp/3P1P1B/4KNBN w - - 0 1"]

*


Help! I cannot understand this game’s notations! I was surfing across Tim Krabbe’s website, as I usually do on occasion, and I found his article DE KOEWEITSE ONSTERFELIJKE," a very interesting tidbit. A game of 34 moves is mentioned in the last paragraph and notations for all of the moves are given. However, I do not understand them at all. There are strange letters for the pieces, such as P T, and D. K is understandable as the King. I suspect that P is for pawn.
Can anyone please explain to me what these symbols mean, and tell me what kind of notation variation that this is? A link to a site that explains it, such as its history, would also be helpful to have. I would also like it if you could put the game in the replayer so that I may better understand the notation.

Can anyone please explain to me what these symbols mean?

These are the abbreviations for the pieces in Dutch. I believe they are almost the same as the German ones (with the exception of the knight = Springer (jumper) in German and = paard (horse) in Dutch (Pferd = horse in German), which are -

T = Turm (= Castle, Rook)
P = Pferd (= Horse, Knight)
L = Laufer (= Runner, Bishop)
K = Koenig (= King, King)
D = Dame (= Queen, Queen)

  I would also like it if you could put the game in the replayer so that I may better understand the notation.

[fen ""]

1.g4 e5 2.Nh3 Ba3 3.bxa3 h5 4. Bb2 hxg4 5. Bc3 Rh4 6. Bd4 exd4 7. Nc3 dxc3 8. dxc3 g3 9. Qd3 Rb4 10. Nf4 g5 11. h4 f5 12. h5 d5 13. h6 Bd7 14. h7 g2 15. h8=B g1=R!! 16. Bd4 Ba4 17. Rh4 Rg3 18. Bg2 gxf4 19. Be3 fxe3 20. Be4 fxe4 21. fxe3 exd3 22. exd3 c5 23. Rc4 dxc4 24. dxc4 b5!! 25. cxb4 Qa5 26. cxb5 Na6 27. bxa5 O-O-O!! 28. bxa6 Rd4 29. exd4 Rb3 30. cxb3 Ne7 31. bxa4 Nd5 32. dxc5 Nb6 33. cxb6 Kb8 34. bxa7 Ka8


Is it possible to get results/crosstables from USCF-rated events before 1990? In my school days in the early 1980's I played in a few USCF-rated tournaments. Once school was over, I dropped out of tournament play and even dropped my USCF membership.

Now, to support my child who is playing in tournaments, I've re-joined USCF. I see that crosstables for tournaments seem to be available going back to 1990. Is it possible to get results from tournaments before then? If so, how?

I personally doubt it, since those were early computer days when I don't think that much of that information could be easily stored long term. I would however suggest contacting the USCF for definitive information. They have moved their headquarters since then, from NY to Tennessee, but it's possible that some records may have survived.

USCF Telephone:  (888) 512-4377 (CHESS)

Customer Support
Monday through Friday - 9:00 A.M. until 5:00 P.M. (Central)

Facsimile: 256.851.0560

Electronic Mail: customerservice@uscfsales.com


What is the "stonewall formation"? I use PyChess to play. It talks sometimes about how White or Black moved their pawns into "stonewall formation."

How do they do that, and what are the position's advantages/disadvantages?

Black usually reaches the Stonewall formation from the Dutch Defense (though QGD is an option as well, if he/she postpones Nf6) and involves putting pawns on c6, d5, e6 and f5. These pawns guarantee a strong grip on the light squares in the center (especially e4, which is often occupied by a knight later on), but weaken the dark squares. Another problem for Black is the light-squared bishop, which is severely limited by its own pawns. A typical Stonewall position is the following:

[FEN ""]

1. d4 f5 2. g3 Nf6 3. Bg2 e6 4. Nf3 Be7 5. O-O O-O 6. c4 d5 7. Nc3 c6

It's hard for White to crack Black's center, but he has many options, of which my favourite is to exchange some pieces and take advantage of Black's bad bishop in the late middlegame and endgame.

As @user1583209 notes, if White tries to reach this formation it's called the  Stonewall Attack – see the linked question for more details.


Where to find chess coaches? I tried my local chess club but they don't have any good recommendations. Could someone recommend a good website to find coaches?

It would be even better if it has sections to match local coaches as well.

Chess.com has a list of chess coaches, searchable by location, rating and other stuff.

In the ICC store you can also hire chess coaches.


How do you checkmate with a rook? How do you checkmate with a Rook and King versus King? Is there a good and fast method? Can you explain it in a good way? Thanks!

I know you're a FIDE Master :), so I suppose you're more interested in this question from a teaching perspective.

The simplest way to understand a checkmate with King and Rook vs King is the idea of the rectangle of the opposing king. Consider this position-

Here, the Black King is restricted by the White Rook in this giant rectangular area of the chessboard. For simplicity, I am not considering the area restricted by the White King, which would be like this -

A simple way (I'll deal with optimizations later) to checkmate is to ensure that this rectangle gets smaller and smaller, so that the Black King is pushed to a corner of the board (more visual representation below with diagrams).

    [FEN "8/8/8/8/4k3/8/8/K6R w - - 0 1"]

     1. Re1+ Kd4 2. Kb1 Kd3 3. Kc1 Kd4 4. Re2 Kd3 5. Kd1 Kd4 6. Kd2 Kc4 7. Re3 Kd4
     8. Ke2 Kc4 9. Rd3 Kc5 10. Ke3 Kc4 11. Ke4 Kc5 12. Rd4 Kc6 13. Rd5 Kb6 14. Kd4
     Kc6 15. Kc4 Kb6 16. Rc5 Kb7 17. Kb5 Ka7 18. Rc6 Kb7 19. Kc5 Ka7 20. Rb6 Ka8 21.
     Kc6 Ka7 22. Kc7 Ka8 23. Ra6#

1. Re1+ Kd4

2. Kb1 Kd3 3. Kc1 Kd4 4. Re2 Kd3 5. Kd1

5...Kd4 6. Kd2 Kc4 7. Re3 Kd4

8. Ke2 Kc4 9. Rd3

9...Kc5 10. Ke3 Kc4 11. Ke4 Kc5 12. Rd4

12...Kc6 13. Rd5

13...Kb6 14. Kd4 Kc6 15. Kc4 Kb6 16. Rc5

16...Kb7 17. Kb5 Ka7 18. Rc6

18...Kb7 19. Kc5 Ka7 20. Rb6

Ka8 21.Kc6 Ka7 22. Kc7 Ka8 23. Ra6# 1-0

Of course, with this method, the one mistake that White must avoid is stalemate -

Rb7?? stalemate!

Optimizations and Tricks.

More experienced players can get to smaller rectangles quicker by looking further ahead.

One trick is to trap the king in a smaller rectangle if it comes too close to the rook. For this, White also has to use the king more actively.

   [FEN "8/8/8/8/4k3/8/8/K6R w - - 0 1"]

   1. Re1+ Kd4 2. Kb2 Kd3 3. Kb3! Kd2 4. Re4! Kd3 5. Rc4

Another trick is to give a rook check when the kings are in opposition.

   [FEN "8/8/8/2k5/8/2K5/8/4R3 w - - 0 6"]

   1. Re5+!? (1. Rd1!) Kd6 2.Kd4

This trick is not necessarily optimal. In the above example, White can actually mate faster with the move 1. Rd1!

   [FEN "8/8/8/2k5/8/2K5/8/4R3 w - - 0 6"]

   1. Rd1! Kb5 2. Rd5+! Kc6 3. Kc4

The above optimization is also made possible by the rook-waiting-move trick. If, in the above position, instead of going to c6, the Black king tries to escape via a4, then the following checkmate is possible.

 [FEN "8/8/8/1k6/8/2K5/8/3R4 w - - 0 7"]

 1. Rd5+ Ka4 2. Rc5! Ka3 3. Ra5#

One more idea is to use king-opposition (in combination with the rook) to push the enemy king behind.

 [FEN "8/8/8/2k5/8/8/2K5/4R3 w - - 0 4"]

 1. Kc3! (1...Kd5 2. Re3!) Kc6 2. Kc4! Kd6 3. Re4

Combining these different ideas, here are two of the most optimal mates possible from the starting position -

   [FEN "8/8/8/8/4k3/8/8/K6R w - - 0 1"]

   1. Re1+ (1. Kb2 Kf4 2. Kc3 Ke5 3. Re1+ Kf6 4. Kd4 Kf5 5. Re4 Kf6 6. Re5 Kg6 7.
   Ke4 Kf6 8. Kf4 Kg6 9. Re6+ Kg7 10. Kg5 Kf7 11. Re5 Kg7 12. Rf5 Kh7 13. Kf6! Kg8
   14. Rh5 Kf8 15. Rh8#) 1... Kd4 2. Kb2 Kd3 3. Kb3! Kd4 4. Kb4 $3 Kd3 5. Kc5! Kd2
   6. Re4 Kd3 7. Re5 Kc3 8. Rd5 Kb3 9. Rd3+ Kc2 10. Kc4 Kb2 11. Rd2+ Kc1 12. Kc3
   Kb1 13. Kb3 Kc1 14. Rd3 Kb1 15. Rd1# *


Playing solely against chess engine? I don't have many friends to play chess with that are at my skill level so many times I am forced to play against the computer. It seems like the computer plays much differently than a human, or at least, so I hear.

Is it necessary to play against humans to increase your ability or can playing against the computer yield the same result?

Playing against an engine is definitely still good practice for your chess. You can typically scale the strength of the engine to make it harder or easier depending on your level. In my experience it tends to be bit boring since most engines tend to favour particular openings and a fairly aggressive style of play.  To combat this you can tell the engine to play a certain line, but this also takes some of the excitement out since you know in advance what the engine will play.

Aside from engines there are always plenty of online options to find a game. For example chess.com is a free site where you can play against basically any strength player. It also offers live matches as well as correspondence games. You can filter by ELO rating to find games against opponents who would suit your skills.


Is castling a king move or a rook move? Most computer chess games consider castling to be a king move. You click on the king and it shows an option to castle.

What do the FIDE's rules say about this though? Is castling a king move, a rook move, both, or neither?

The FIDE rules say this about castling:

  This is a move of the king and either rook of the same colour along
  the player’s first rank, counting as a single  move of the king


Ideas to improve chess books usability in the XXI century I enjoy reading a book of chess on the outside, with my iPhone (and Stockfish) to explore situations. However, I spend too many time setting up the board manually. So here's a crazy idea (patent-free): Encode board positions (FEN) in QR-Codes! Example:

What other simple ideas could improve the usability of current (printed) books?

I've long felt that scripting short systems of moves in their chess notation would be very helpful as a teaching tool as well.  There are many, many projects out there that can replay a set of instructions, and it would make it much easier to not only show how to set up some of the basic openings, but also explore their ramifications in response to different positions.


Assigning Engines in Arena How does one assign a specific engine to a specific color in Arena?  I load a PGN file and move to a specific point in the game.  At that time I want to assign Engine A to play black and Engine B to play white.  Then when I hit the calculate or demo buttons the game proceeds (after selecting "New Variation").  I've spent half the day searching for the answer with no luck.  Any guidance would be greatly appreciate.

Are you looking for setting up two engines playing against each other? In that case you can use the following in Arena 3.5: Engines > Tournament.


Use of transposition tables in chess engines I hope this is the right place to post this question. So I like to implement things myself without using libraries and one of my first projects was a chess engine and I would like to improve this one.

I got multiple questions:

  How are transposition tables used? Usually the serch algorithm has a
  fixed depth so we cannot "evaluate" non-leafs with the transposition
  tables, right? So the only purpose would be to hash the board
  evaluation of the leafs. Is this correct?

  I am using Java without multithreads. Is it worth to look into magic bitboards and switch to C++? They seem to be pretty messy at the first glance.

  How many nodes per second are realistic to reach with a "simple" engine. I got up to 1E6. I know that Stockfish reaches 80E6. Is it more worth to improve on nodes per second or on the algorithm itself?

I am very happy for any help.

Depends on the program and how they implemented it. Many have memorized openings and transpositions later on in the game are usually short enough that the depth of analysis handles it.
Not for me.  But I am old school when it comes to programming.  You may or may not like C++.
Nodes/sec depends on the hardware, opsys, language, and your coding.  The algorithm is far more important for good results.


Novice question about openings Although I think I've played a lot of games, my ability is still very low. I've never read any books on chess. Perhaps this explains my poor games.

As I'm starting to research some chess online, I'm left wondering why people focus on particular openings. Surely these are all well researched by people, and you'd end up just playing through the motions of what a computer would do in certain situations. Why don't people open with more randomness, in a sort of pieces scattered to the wind style? Surely opponents won't be expecting it and games will be played anew for both players.

Should you think the above is rubbish, please point towards a book/site that I should read.

Openings have been classified roughly as being very "tactical and sharp" versus "positional and dull". For example: e4-e5 (king's pawn), e4-c5 (sicilian defense) fall under the former category, whereas d4-d5 (queen's pawn), e4-c6 (caro-kann defense) under the latter. But not all games strictly follow the above thumb rule, each opening can transpose to either tactical or positional depending on the lines chosen in the middle game.

That said, players chose their liking of openings and study various lines originating from the opening. Once the number of moves reaches 2 or above, the possibilities grow exponentially and hence most of the times will not result in the exact same game that the people had studied earlier, even at the grandmaster level, let alone amateurs.

You could open randomly, but in doing so you will be violating the basic opening principles and hence will most likely lose the game against an experienced player. You can check out the following link for some opening guidelines-

http://www.danheisman.com/opening-principles.html


Looking for pgn openings file I am looking for a file containing several (>50 let's say) popular openings in PGN format.

The aim is to use it with cutechess to do engine testing on different opening scenarios.

I would recommend that you take a look at the Silver Openings Suite by Albert Silver. It's a hand-crafted set of 50 opening positions designed for balanced play, based on some non-trivial statistical analysis using ChessBase.

Cheers!


Is there a difference between +W -L =D and +W =D -L? Is there a difference between a player's tournament or match result being reported in the format +W -L =D and in the format +W =D -L? (where W is number of wins, D is number of draws, L is number of losses)
Obviously they're functionally equivalent and I feel like I have encountered both, but I'm not entirely sure if one is more standard/common or more technically correct/official than the other (or was originally considered to be so). Is there any difference in the circumstances where you use one or the other, or are they always mutually equivalent?

The only difference is the sequence they are written down.
Some like WLD so you can easily see the difference in scores.
Some like WDL as that goes from best to worst in sequence, but makes it harder to compute the difference at a glance.
Compare to TV channels showing football scores.
some have score1 team1  score2 team 2
others have team 1 score1  score2  team 2
some might even have score1 team1 team2 score2
clearly the middle one is easiest to see at a glance how the game score is without having to search and ensure you matched the right score to each team.  You know who is playing and all you need is the two scores and which one belongs to one team.  The middle one does that best.
It is just preference. And PHBs are not good at considering things like ease of use or other significant factors.


Why isn't 3.e4 more popular in the QGA? According to the chess.com DB, 3.e4 is the third most popular reply in the Queen's Gambit Accepted - but why isn't it the most popular by a long shot? Isn't the entire point to remove black's central d-pawn so white can play a strong e2-e4? The moves 3.Nf3 and 3.e3 seem passive almost, but surely I am missing something. Maybe e2-e4 is taking up too much space too early, and you end up overextending yourself?

I'm not sure which database you are looking at: I see 3.e4 as the second, not third, most popular choice on chess.com, though not by much:

Here's what one author says about 3.Nf3:

  Throughout the history of the Queen’s Gambit Accepted, this has been
  White’s most popular move in this position. White does not hurry to
  win back the pawn that he has sacrificed. He calmly develops his
  pieces and offers his opponent as few targets for an immediate
  counterattack as possible.

Sterren, Paul Van der. FCO: Fundamental Chess Openings (Kindle Locations 1487-1489). Gambit Publications. Kindle Edition.

and about 3.e4:

  For a long time this very natural reaction to 2... dxc4 suffered the
  same fate as 3 e3 and 3 Nc3: it was thought to be inaccurate because
  of 3... e5. The difference is that in this case White has the
  promising pawn sacrifice 4 Nf3! exd4 5 Bxc4!, when his development is
  swift and aggressive and Black will have to take great care in getting
  his king into safety. This is in fact a lively variation with chances
  for both sides.

  [...]

  Another standard device for counterattacking against the white centre
  consists in 3... c5.

Sterren, Paul Van der. FCO: Fundamental Chess Openings (Kindle Locations 1438-1441). Gambit Publications. Kindle Edition.

My take is that it is not that 3.e4 is bad (it actually has better statistical results for White!), but it is a matter of taste and more people prefer to play more solidly.


Must one say "queen check" before capturing a queen? I was playing a friend and I took her queen. She said that I didn't say "queen check" beforehand. I have never heard of this. Is it a rule?

The official FIDE laws of chess do not know about a queen check. Announcing a  "queen check“ might even be considered a case of "to distract or annoy the opponent“ (11.5). Even announcing a "king check“ is not recommended.
That’s for tournament chess. In informal games, it is not unusual in some groups to announce a check and a "queen check“ (by "gardez“, French for "keep attention“). Even there it is not a rule, but a courtesy. Not announcing a check or gardez is considered impolite, but you may take the queen anyway.


Is there some online chess board where you can teach a kid how to play? A family friend wants to teach her grandchild how to play chess. The problem is that, due to the pandemic, they live apart from each other, so she has to do this online. Is there some website where the players can set up the board by themselves and only then start playing i.e. a website where you start the game as you would if you were playing OTB, which is by first setting up the board?
I am aware of Lichess' board editor (https://lichess.org/editor), which can be tweaked to work in the specific case from above (the kid can clear the board, set up the pieces by himself, send the invite link and then they may play), but I wonder if there is some better resource that I don't know of.

The websites lichess.com and apronus.com are your best options to chose from. They both do the same thing, but I suggest you use apronus.com.
You can set up the board by yourself, send an invite link, and do other things just like you want.


Shocking queen sacrifices? I am a chess beginner and I find queen sacrifices are the most shocking moves I have ever seen.

Please, can you provide me with some shocking examples of queen sacrifices. It need not be a big list, a handful would work just fine.

My favourite is this one, it has a nice anecdote attached to it, too. Supposedly, in the situation shown on the board, due to his overwhelming advantage, the white player has kindly asked his rival on which square he would like to receive the checkmate. The black player responded:

   g1 (as this he thought least likely within the foreseeable future)

[White "Edward Lasker"]
[Black "George Alan Thomas"]
[FEN "rn3rk1/pbppq1pp/1p2pb2/4N2Q/3PN3/3B4/PPP2PPP/R3K2R w KQ - 0 1"]

1. Qxh7+ Kxh7 2. Nxf6++ Kh6 3. Neg4+ Kg5 4. h4+ Kf4 5. g3+ Kf3 6. Be2+ Kg2 7. Rh2+ Kg1 8. Kd2# {Some sources say 8. 0-0-0#} 1-0

Another shocking queen sacrifice comes from this game, which is by some called the most beautiful in the history of chess. The result of the sacrifice is an instant resignation.

[Event "18th DSB Kongress"]
[Site "Breslau GER"]
[Date "1912.07.20"]
[EventDate "1912.07.15"]
[Round "6"]
[Result "0-1"]
[White "Stefan Levitsky"]
[Black "Frank James Marshall"]
[fen "rnbqkbnr/pppppppp/8/8/8/8/PPPPPPPP/RNBQKBNR w KQkq - 0 1"]

1.d4 e6 2.e4 d5 3.Nc3 c5 4.Nf3 Nc6 5.exd5 exd5 6.Be2 Nf6 7.O-O Be7 8.Bg5 O-O 9.dxc5 Be6 10.Nd4 Bxc5 11.Nxe6 fxe6 12.Bg4 Qd6 13.Bh3 Rae8 14.Qd2 Bb4 15.Bxf6 Rxf6 16.Rad1 Qc5 17.Qe2 Bxc3 18.bxc3 Qxc3 19.Rxd5 Nd4 20.Qh5 Ref8 21.Re5 Rh6 22.Qg5 Rxh3 23.Rc5 Qg3 0-1

Fischer's "Game of Century" - played by him when he was only 13 years old!

[Event "Third Rosenwald Trophy"]
[Site "New York, NY USA"]
[Date "1956.10.17"]
[EventDate "1956.10.07"]
[Round "8"]
[Result "0-1"]
[White "Donald Byrne"]
[Black "Robert James Fischer"]
[fen "rnbqkbnr/pppppppp/8/8/8/8/PPPPPPPP/RNBQKBNR w KQkq - 0 1"]

1. Nf3 Nf6 2. c4 g6 3. Nc3 Bg7 4. d4 O-O 5. Bf4 d5 6. Qb3 dxc4 7. Qxc4 c6 8. e4 Nbd7 9. Rd1 Nb6 10. Qc5 Bg4 11. Bg5 Na4 12. Qa3 Nxc3 13. bxc3 Nxe4 14. Bxe7 Qb6 15. Bc4 Nxc3 16. Bc5 Rfe8+ 17. Kf1 Be6 18. Bxb6 Bxc4+ 19. Kg1 Ne2+ 20. Kf1 Nxd4+ 21. Kg1 Ne2+ 22. Kf1 Nc3+ 23. Kg1 axb6 24. Qb4 Ra4 25. Qxb6 Nxd1 26. h3 Rxa2 27. Kh2 Nxf2 28. Re1 Rxe1 29. Qd8+ Bf8 30. Nxe1 Bd5 31. Nf3 Ne4 32. Qb8 b5 33. h4 h5 34. Ne5 Kg7 35. Kg1 Bc5+ 36. Kf1 Ng3+ 37. Ke1 Bb4+ 38. Kd1 Bb3+ 39. Kc1 Ne2+ 40. Kb1 Nc3+ 41. Kc1 Rc2# 0-1

The "Swindle of the Century" game. Perhaps not very spectacular, but how shocking it must have been to the black player!

[Result "1/2-1/2"]
[White "Larry Melvyn Evans"]
[Black "Samuel Reshevsky"]
[fen "2Q5/5Rpk/8/1p2p1qp/1P2Pn2/4rPPP/7K/8 w - - 0 1"]

1. h4 Re2+ 2. Kh1 Qxg3 3. Qg8+ Kxg8 4. Rxg7+ 1/2-1/2

The "Immortal Draw" game:

[Event "Vienna"]
[Site "Vienna"]
[Result "1/2-1/2"]
[White "Carl Hamppe"]
[Black "Philipp Meitner"]
[fen "rnbqkbnr/pppppppp/8/8/8/8/PPPPPPPP/RNBQKBNR w KQkq - 0 1"]

1. e4 e5 2. Nc3 Bc5 3. Na4 Bxf2+ 4. Kxf2 Qh4+ 5. Ke3 Qf4+ 6. Kd3 d5 7. Kc3 Qxe4 8. Kb3 Na6 9. a3 Qxa4+ 10. Kxa4 Nc5+ 11. Kb4 a5+ 12. Kxc5 Ne7 13. Bb5+ Kd8 14. Bc6 b6+ 15. Kb5 Nxc6 16. Kxc6 Bb7+ 17. Kb5 Ba6+ 18. Kc6 Bb7+ 1/2-1/2

You can find many more in these game collections:

http://www.chessgames.com/perl/chesscollection?cid=1002707
http://www.chessgames.com/perl/chesscollection?cid=1022437
http://www.chessgames.com/perl/chesscollection?cid=1000116


How do you read this opening table presented in Modern Openings? How do I read this table presented in the book "Modern Openings"? Specifically, what do the rows, columns and the dashed lines represent? Finally, there are also little letters like (a) which are probably related to explanations that come up later in the book.

The columns represent the main variants which continues the movements at the head of the table. White's moves are followed by Black's in the same column. The numbers to the left of the table are the movement numbers.
The ellipsis are there to group the variants. For example, after 3 Nf3 g5 you can play 4 h4 or 4 Bc4. If White chooses the continuation 4 Bc4 he will find that Black's most sensitive responses are 4 ... Bg7 or 4 ... g4.
The lower case letters in parentheses are notes, which follow the table, which show alternative lines considered less important or that show possible pitfalls. The mark in the last move of each column refers to the model game. The evaluation of the final position is expressed with words instead of symbols such as = (equal) or + / = (the target is slightly better).


Draws, en passant, and the FIDE's 2014 rulebook revision Effective July 2014, the FIDE has revised its Laws of Chess.  Some questions occur regarding the revision, including one re draws and en passant.

[Title "Black to move"]
[FEN "1rb1kbnr/ppppqppp/6n1/4P3/8/1PN5/P1PP2PP/1RBQKBNR b kq - 0 1"]

1... d5 2. Ra1 Ra8 3. Rb1 Rb8 4. Ra1 Ra8 5. Rb1

After Black pushes his queen pawn two squares, White could capture en passant, except that the capturer is pinned against its king.  So instead (just to illustrate the point), our players start shuffling their rooks back and forth.

After 5. Rb1, can Black write 5... Rb8 on his scoresheet, stop the clocks, and claim draw by repetition?

Another way to ask the question: is the en passant position Black's move 1 introduces effectively an en passant position after all, according to the FIDE's revised Laws of Chess?

DISCUSSION AND REFERENCES

Laws of Chess, sect. 9.2:

  The game is drawn, upon a correct claim by a player having the move, when the same position for at least the third time (not necessarily by a repetition of moves): (a) is about to appear, if he first writes his move, which cannot be changed, on his scoresheet and declares to the arbiter his intention to make this move, or (b) has just appeared, and the player claiming the draw has the move.  Positions are considered the same if and only if the same player has the move, pieces of the same kind and colour occupy the same squares and the possible moves of all the pieces of both players are the same. Thus positions are not the same if ... at the start of the sequence a pawn could have been captured en passant....

To me, this says that Black can indeed claim the draw mentioned above.  However, decades of experience suggest that different players can understand the same rulebook language differently, especially in obscure cases like the present one.  Is it possible to read this rule differently?  One would like to be sure.

Related, earlier questions and answers on StackExchange, predating the FIDE's July 2014 revision, include this.

Further reading: Geurt Gijssen.  Arbiter's Notebook.

Positions are considered the same if and only if the same player has the move, pieces of the same kind and colour occupy the same squares and the possible moves of all the pieces of both players are the same.

After 5...Ra8, the same player has the move, pieces of the same kind and colour occupy the same squares and the possible moves of all the pieces of both players are the same. Therefore, Black can claim a draw.

  Thus positions are not the same if ... at the start of the sequence a pawn could have been captured en passant....

At the start of the sequence the pawn could not be captured en passant.


In chess engines (A.I) how are the values for Piece-Square Tables for simplified evlaution function determined? I wanted to know how are the values for piece square table are determined for simplified evaluation function in chess A.I engines

For example

Source :

https://medium.freecodecamp.org/simple-chess-ai-step-by-step-1d55a9266977

They're mostly based on mobility, and have been modified by repeated test cases.  Knights have more squares available when on the center 16 squares(8) than in the corner(2), therefore the central square have a higher value.  After the computer plays many games, these values are adjusted based upon how well the pieces actually preformed on the various squares.  Beginners are taught that the more centralized piece is better placed, and the computer is taught this basic rules via these tables.

Extra table talk:  King Tropism is a table, usually written dynamically, that indicates king safety.  It adds up the score of the squares around the king based upon how many times their attacked and defended.

Chess based table:  The table being static is a poor valuation tool.  The b5 square is normally a good place for the bishop.  However, when there's no knight on c6, the bishop is useless on b5.  In the French defense, where there's pawns on d5 and e6, the bishop is less than useless as it gives black both a target and the opportunity to exchange his bad bishop.


In the shown position, should I push pawns or trade material? In the following (now finished) game, I was unsure at this point how to proceed. One thought was to take the pawn at d4 with the rook, in order to entice a rook/rook trade since I'm up on material. But I was also thinking that I could use my advantage at that point to start pushing the abc pawns.
I ended up taking the pawn, and it worked, but I'm still not sure what the best approach in that situation was. Despite being ahead, I had no idea how to organize my forces into a coherent attack.
[FEN ""]
[StartPly "53"]
[StartFlipped "1"]
[White "SpartanDonut"]
[Black "almo2001"]
[Result "0-1"]
[WhiteElo "1085"]
[BlackElo "1143"]
[TimeControl "1/604800"]

1. d4 d5 2. Bg5 f6 3. Bh4 Nc6 4. e3 Bf5 5. Bd3 Nh6 6. h3 e6 7. Nf3 Nb4 8. a3 Nxd3+ 9. cxd3 Bd6 10. Nc3 O-O 11. e4 dxe4 12. dxe4 Bg6 13. O-O Be7 14. g3 f5 15. e5 Bh5 16. Kg2 g5 17. Qb3 gxh4 18. Qxe6+ Kg7 19. Nxh4 Bxh4 20. gxh4 Bf7 21. Qf6+ Qxf6 22. exf6+ Kxf6 23. f4 Rad8 24. Rad1 Bd5+ 25. Nxd5+ Rxd5 26. Rfe1 Rfd8 27. Re5 Rxd4 28. Rxd4 Rxd4 29. Kf3 Nf7 30. Rb5 b6 31. Ke3 Re4+ 32. Kf3 Nd6 33. Re5 Nc4 34. Rxe4 fxe4+ 35. Kxe4 Nxb2 36. f5 Nc4

Should I push pawns or trade material?

Good question. You are winning either way but it's always more relaxing to win the easy way rather than the hard way.
The key in these sorts of endgames is how active the pieces are. Black's knight on h6 is terrible. It is doing nothing really useful and has no prospects unless it moves somewhere else. White's rook on e5 is very active. The rook on d1 is passive, albeit it is doing an important job of trying to defend the d4 pawn. The d4 pawn is undefendable so white would do well to jettison it in return for activity. White's next move should probably be Rde1 almost regardless of what black does. The two black rooks are attacking the white pawn and so are reasonably active.
If you were to start immediately pushing the queenside pawns then the obvious first move would be c5 because the d4 pawn is pinned. The idea would be to take with the c pawn and have a protected passed pawn but I don't think it is that good move. There is no rush. White's d pawn is yours whenever you want it. Try and look for better ideas.
The one really annoying thing about white's position is that rook on e5. So, for me the best move is Nf7 kicking it away. It also starts the process of moving the knight to a really good square. To my eye e4 looks like an excellent square for the knight. That is really going to annoy white and make life difficult. I would aim to get my knight there first and then think of taking the free pawn on d4.
Maybe something like this:
[fen "3r4/ppp4p/5k1n/3rRp2/3P1P1P/P6P/1P4K1/3R4 b - - 0 1"]

1...Nf7 2. Re3 (2. Rxd5 {alternatively} Rxd5 3. Kf3 c5 4. Ke3 Nd6 {Nc4+ is calling me} 5. b3 {stopping that idea} cxd4+ {Nb5 was another way of winning the pawn} 6. Rxd4 Rxd4 7. Kxd4 Nb5+ 8. Kc5 Nc7 {Nxa3 is also good} 9. Kd6 Ne6 10. b4 Nxf4 11. Kc7 Nxh3 {and the f pawn will queen long before white can get anywhere near queening on the queenside}) Nd6 3. Rc3 c6 4. b4 Ne4 (4...Nb5 5. Rcd3 Rxd4 6. Rxd4 Rxd4 7. Ra1 Rxf4 {and it is just hopeless for white}) 5. Rcd3 Rg8+ 6. Kf3 Rg3+ 7. Ke2 Rg2+ 8. Kf3 Rf2+ 9. Ke3 Rh2 {and the h pawns are falling and white is still tied up in knots}


How has the frequency of FIDE rating lists changed over the years? Today FIDE publishes a new rating list once a month. When FIDE first started publishing official lists in 1971 they came out once a year. How has the frequency changed over the years? When did the frequency change and by how much?

The period before 2001 is documented on the Olimpbase site. The period from 2001 on is documented on the FIDE rating site.

To find the details for pre-2001 go to the Olimpbase site and about a third of the way down on the right hand side under "PLAYERS & TEAMS" click on "Elo lists 1971-2001".

To find the details for 2001 and after go to the FIDE rating download site and halfway down click on the dropdown box "Download old files from Archive - Please select your period and press GO".

Both these sites give the possibility to download the lists in zip file format.

Pre-2001

Unofficial lists were published in -
June 1967, April 1968, 1969 (no month given), 1970 (no month given) and January 1971

Official lists were published in July of the following years:
1971, 1972, 1973.

This switched as a one-off to May in 1974 before settling down to full lists published in January in 1975 through to 1980 with the addition of three supplementary lists in July of 1978, 1979 and 1980. These supplementary lists included less than 10% of players.

In 1981 FIDE switched to publishing lists twice a year, in January and July, and this continued from 1981 through to 1999.

This period was also significant for the introduction of a number of new features:

FIDE IDs in 1990, although the first attempt in January 1990 only had
5 digit IDs. This was clearly going to be inadequate and the length
was extended in July 1990.
With the break up of the USSR new federation codes were introduced
for ex Soviet, Yugoslav and Czechoslovak republics.
"Active / Inactive" flags were introduced in July 1992.
The rating floor for men was lowered to 2005 in January 1993.
Ratings stopped being rounded to the nearest 0 or 5 in January 1999.

In 2000 three rating lists were published in January, July and October.

In 2001 the frequency changed to 4 times a year. Lists were published in January, April, July and October from January 2001 up to July 2009.

From September 2009 through to July 2012 lists were published every two months in January, March, May, July, September and November.

In January 2013 they changed to being published monthly through to the current day.

Although it should be noted that the actual download files themselves are updated on an almost daily basis. For instance, I am posting this on 9th September 2019 and that is also the date on the download file. Two days ago the date was 7th September. The information in the two files is almost the same. The differences are minor corrections and additions. The data in the September files is still significantly different from the August files in that the August files reflect data reported in July while the September files reflect data reported in August.


Order of pieces in one-dimensional array To store pieces inside an array of 64 squares (inside a one-dimensional chessboard), I would simply convert squares like:

0 is a8
1 is b8
2 is c8

...

63 is h1

This order would be natural for me, as we can then easily loop and display each square to represent the board on a document, having at the bottom the white perspective.
But looking at some documents on the computer chess, such as the 0x88 board representation, it seems that the standard way to order pieces in rather this:

0 is a1
1 is b1

...etc.
Do you think I should definitivly use this same ordering?
Or would it make more sense to adopt the more natural order (0 is a8)?

They're both equally natural, they just start at a different square. But that choice is arbitrary anyway. Printing to a terminal is one of the least critical things a chess engine does with a board, and looping can go in the other direction just as easily.
If you want to be able to easily copy algorithms or code from examples or other engines (the license of which allows you to do that), it can be helpful to use the same conventions as most people do. But that's completely up to you.