Is there an easy way to find out the name of a variation? I want to know the names of the variations in the Ruy Lopez Chigorin, for example:

[FEN ""]
1.e4 e5 2.Nf3 Nc6 3.Bb5 a6 4.Ba4 Nf6 5.O-O Be7 6.Re1 b5 7.Bb3 d6 8.c3 O-O 9.h3 Na5 10.Bc2 c5 11.d4 Nd7

I look at the opening classification on Chessbase but it's not very detailed with names. Also chess365.com.

Is there anywhere else I can see names of variations?

My free, open-source software, pgn-extract, provides a file eco.pgn that provides names for ECO codes. This file can be used with pgn-extract to add ECO tags to game scores: see its -e flag. For instance, the tags it produces for the moves: 1.e4 e5 2.Nf3 Nc6 3.Bb5 a6 4.Ba4 Nf6 5.0-0 Be7 6.Re1 b5 7.Bb3 d6 8.c3 0-0 9.h3 Na5 10.Bc2 c5 11.d4 Nd7 * are:

[ECO "C96"]
[Opening "Ruy Lopez"]
[Variation "closed, Keres (...Nd7) defence"]

That might provides some degree of what you are looking for.


Encyclopaedia of chess openings in machine readable form I am building an app that allows the user to track openings in visual form. They will make moves on the board and the name of the opening and common next moves will be displayed. Now I need some data to do this. First is a database of games to search so I can work out the most common next moves. This I have done by downloading PGN files.

Secondly, I need data on the opening names. I understand there is an Encyclopaedia of Chess Openings which has named and categorised thousands of openings. Does anyone know if this encyclopaedia is available in machine readable form (eg an xml or db file)? Either free or for a small fee?

SCID has a text file that you can use. It begins like this:

# scid.eco
#
# Encyclopaedia of Chess Openings file for Scid vs. PC
#
# Copyright (C) 1999- Shane Hudson and others.
# Last updated: Febuary, 2014
#
# In addition to standard ECO definitions, scid.eco allows for extensions:
# Each basic code can have a lower case letter extension (a-z), and an extra
# level (1-4). So the order of ECO codes for A00 is:
# A00, A00a, A00a1, A00a2, A00a3, A00a4, A00b, A00b1, ..., A00z4.
#
# You can convert this file to PGN format with the "eco2pgn.py" script,
# and to EPD with the "eco2epd" (use "make eco2pgn").

A00a "Start"  *
A00b "Barnes Opening"  1.f3 *
A00b "Fried fox"  1.f3 e5 2.Kf2 *
A00c "Kadas Opening"  1.h4 *
A00d "Clemenz Opening"  1.h3 *
A00e "Ware Opening"  1.a4 *


Chess challenge from a newspaper in 1927 (win in 2 moves) I have been trying to solve this for a long time, but can't find a solution. How can white force a checkmate in 2 moves?

1R6/4p3/2pkB3/4n1N1/8/1N2K1B1/8/8 w - - 0 1

Ask yourself: what would Black do if he were to move? After 1... Kc7, 2. Bxe5 is mate. His other option is 1... c5, threatening to escape with 2... Kc6.

The solution:

   1. Nc5! blocks the c-pawn. Black gets the additional option of 1... Kxc5, but after that, 2. Ne4 is mate.

(I can post an interactive version, but that doesn't work with spoilers. And it's a good visualization exercise.)


Is there any android app or software that allow me to create my own chess puzzle so I can solve or study it later on? I want to improve my tactics skills; is there any Android app or software that allows me to create my own chess puzzle so I can solve or study it later on?

LiChess or Chess.com have apps accessible to Android, in which you can find an analysis board and study from there. You can save the boards as well until further use.
Plus, there are a lot of features, such as finishing game with computer, analysis from engine etc.


How does engine strength scale with hardware? Say I run Komodo on my 4-core machine. How much stronger would Komodo be if I used an 8-core machine? A 40-core machine? A 4000-core machine?

Is there a general relation for this? Also, does this scaling depend on which engine is used, and if so, why?

Multicore is important for chess engines, but it doesn't scale forever.

Up to certain depth, no matter how much hardware you have, you just don't have enough computational power
Yes. Scaling is heavily implementation dependent. For example, a simple mutex would make multithread programming much easier (any decent programmer will agree here), but that'd also make the engine run much slower than another engine runs without mutex locking.
40 cores machine will play stronger than an 8-core machine, although it's hard to state how much. A 4000 core machine should also play stronger than a 40 core, but it's harder to justify the costs for smaller Elo improvement.


Moving two pieces together Can one open by moving two pawns at a time, one square forward for each? (I hope you don't think I'm being funny-I was taught this when playing at school and have always played with this option).

Not in a regular chess.

There are some "homemade" rules at least in some parts of the world that allow you to open with two moves (so only at the start of the game), but those are not used on any serious level.

So no, you can't move two pawns in the same move.


If there was perfect play from both sides, will it be draw or win for one? If there was perfect play from both the colors, will white win because of the first move advantage or will it be a draw?

Most Grandmasters will argue that chess is a draw with perfect play from both sides. However, in practice it is shown that white has higher win rates than black, but this is due to the first-move advantage. This is because white technically gains a small advantage from having the first move, and black will equalize with their move.

It is possible that a first-move could cause a disadvantage with perfect play, because despite having perfect information, the black player could potentially be able to counter any strategy white attempts to play. It is more likely however that if one side were to have a forced win, it would be for white.

The answer to this question will not be known for a long time because only in 2012 were endgame tablebases able to solve any position with 7 pieces perfectly (including the 2 kings). For comparison of how impressive this feat is, 6 pieces was only solved in 2005. Obviously, this problem is exponential because with more and more pieces, the complexity increases further and further, until eventually the game is solved for 32 pieces. One could argue that the starting position is static so we don't have to consider every combination of 32 pieces on the 64 squares, but the number of possibilities is still enormous and will take a long time to know for certain.


Centre pawn vs. side pawn? Chess theory suggests that pawns whose file is nearer to the central files are more powerful. This is somewhat obvious for the rook's pawn, which can attack only one square as opposed to the other pawns, which can each attack two squares. However, in practice, even the rook's pawn turns out to be somewhat useful as a pawn at a3 or h3 can deter the opponent bishop coming to b4 or g4.
In practice, are the pawns on central files really more powerful than the pawns on the side files? What is the reason? Does the situation change during the end game as opposed to the openings?

The more pieces on the board,  the more powerful the center pawns. This is typical for most opening and middlegame positions. The most convenient place for pieces to travel is usually through the center of the board, and the center pawns help to control that area.

The less pieces on the board, the more powerful the wing pawns. Less pieces on the board means less need to control pieces travelling through the center. A passed wing pawn is harder to stop than a passed center pawn. Your opponent needs to go further to the edge to defend against it. This can really stretch out and discoordinate his pieces if he has to defend against another weakness on the other side of the board. The outside passed pawn is like a decoy.

Generally speaking, you can think of Center pawns becoming weaker and weaker as pieces are exchanged, and wing pawns stronger the closer you reach an endgame.


Are there moves in chess that are considered unsporting? In many sports, you often find legal tactics that are considered unsporting by fans, spectators and/or opponents. For example, in football (soccer), it is often considered unsporting to simply pass the ball around your back defenders instead of trying to attack. Are there any similar situations in chess?
Some examples that I can think of: perhaps it is considered unsporting, or perhaps indicative of lack of skill, to promote 5 pawns and crush your opponent instead of looking for a more elegant mate in a winning position. Also, in my school days, we used to think of scholar's mate as a bit ... unsatisfying. There even used to be a meme going around that scholar's mate is not allowed (probably started by the coach to get the kids to play "proper" chess).
To be clear, I'm not so much looking for unsporting behaviour as unsporting moves. I can imagine it being very unsporting to, for example, let your clock run out when you still have 40 minutes left rather than resigning in a lost position, forcing your opponent to hang around just in case you actually make a move.
Are there any other examples you can think of? Or is chess a case of - if it's legal, then it's good?
Update: Just as I was starting to think that unsporting moves are few and far between, Kamsky and Gareev played to a controversial draw by three-fold repetition in round 1 of the US champs. According to the GM's doing the analysis, Kamsky was pretty much forced into the draw, but Gareev had the opportunity to play an alternative move to continue with the game.
So let's say you have the following situation: player A plays against a much stronger opponent B. By luck or miracle, player A finds himself ahead in the game, and see the opportunity to force a draw (or maybe he is so far ahead that he knows player B would accept a draw if offered). Is it unsporting for him to draw the game then?

What is "unsporting"? To my mind (backed up by the two or three definitions I quickly browsed), it's mostly about behaviour. To act sportingly is to be fair and respectful, to play for the (mutual) enjoyment of the sport, and—here's the tricky part—to not abuse the rules for an unfair advantage.

Unsporting behaviour in general, and the last kind in particular, often leads to new rules being introduced. ("No underarm bowling in one-day cricket" is the first example that comes to mind.)

I can't think of anything on the board (as opposed to players' behaviour, or abusing the clock) that would strike me as unsporting. And the lack of new rules to counter anything on the board would seem to support that view.

So essentially, no: in standard chess, "if it's legal, then it's good". People might complain about how some style of play (whatever's new and trendy and effective) is changing the spirit of the game or whatever, but so far everything still seems to be fair play.


Why not take the bishop with the knight (Guseinov vs. Bauer)? In this game between Guseinov (2622) vs. Bauer (2634):

Crete 2007 · French, Winawer, Alekhine (Maroczy) gambit (C15) · ½-½

[FEN ""]

1.    e4    e6
2.    d4    d5
3.    Nc3    Bb4
4.    Nge2    Nc6
5.    a3    Ba5
6.    b4    Bb6
7.    Na4    dxe4

After dxe4, Guseinov played 8. Bb2.

Why did he not take the black dark square bishop on the b6 square with his knight on a4?

There is no hurry. After 8. Bb2 the bishop on b6 is not going anywhere. NxB continues to be available to white until black does something about it like a6. That means that delaying NxB gains a tempo if black has to make a less useful move to try and "save" the bishop like a6. Since recapturing with the a pawn probably gives black a better game it is worth waiting to see if he will throw away this option by playing a6.

Delaying the capture also retains the possibility of playing Nc5 which may be stronger in some circumstances.

Finally an immediate NxB will be met by axN opening the a file for black and allowing the a8 rook to pressure the now weak, backward a3 pawn.

So, in short, delaying the capture retains flexibility. That way white has more and possibly better options. This "maintaining the tension" is one of the things which separates weak and strong players. Weak players are in too much of a hurry to release the tension in a position. Strong players maintain the tension and with it give their opponents more opportunities to go wrong.


What is a good French-like defense against 1. d4? I enjoy playing the French Defence as black against 1. e4, for the following reasons.

It often creates a closed position without wild tactics
It takes white away from the more familiar lines (1... e5 and 1... c5)
If black survives the attack, black will likely have a better pawn structure for the endgame.
It doesn't involve a kingside fianchetto, which never seems to work out for me.

I'm curious what would be a similar option against 1. d4. I find that when I try to play positionally, looking for long-term advantages, I often find myself in extremely symmetrical, drawish positions.

I'd like a system to play against 1. d4 that is not extremely common and is reasonably safe, and not prone to symmetrical positions.

I'm strictly a club-level player that has no aspirations of being competitive with class-A players.

One option is to play 1... e6 against 1. d4 anyways!

After 1. d4 e6, white doesn't really have a choice other than to transpose into a standard opening anyways.  If white plays 2. e4, well that's just the French Defense that you know and love.

If white plays something else, like 2. c4 (as most Queen's Gambit players will), then you have a few options:

Queen's Gambit Declined (2... d5)
You have to be prepared here because white will most likely know a few good openings.  There are some obvious similarities between the French and the QGD (black's light square bishop!), but there are a few key differences that you will need to practice.
Benoni (2... c5)
If you don't want to deal with a symmetrical game, the Benoni is a good option.  However, this is likely to lead to a fairly tactical game after 3. d5 exd5 4. cxd5 d6.  Since you weren't thrilled about a tactical melee, that brings us to the...
Dutch Defense (2... f5)
Although the Dutch Defense doesn't have the best reputation, it fits your criteria: it's not very tactical (at least the Stonewall, the Leningrad is a totally different story!), black will have some positional trumps (namely the e4 square), and it's offbeat enough.  Black's simple plan is to setup pawns on f5, e6, d5, and c6 and then stick a knight on e4.  The whole battle revolves around control of the e4 square, and black has had good results with the Stonewall Dutch.

After mentioning all that, 1. d4 e6 2.c4 can also lead directly into Indian structures with either 2... Nf6 or 2... b6 (the Nimzo and Queen's Indian respectively).  If you are familiar with one of these openings, this is a good way to try to get a French, but fall back on a main line opening if your opponent doesn't oblige with 2. e4.


How many FIDE rated games are played per year? I was surprised not to be able to easily find this statistic. How many FIDE rated games are played around the world each year?

I was surprised not to be able to easily find this statistic.

The information is available with quite a lot of work from data which FIDE makes available on its website. The key page is the Ratings Download page. If you are an arbiter and you use a FIDE approved pairing program (e.g. Swiss Manager or Vega) then when you click the button to auto-magically update FIDE player details and ratings it will start by downloading and processing one of the files linked to on this page.
You don't have to be a pairing program to download files from this page. Anybody can do it. For me there are 4 important files -

Download full list of players (not rated included) ... XML format
Download STANDARD rating list ... XML format
Download RAPID rating list ... XML format
Download BLITZ rating list ... XML format

These files are updated by FIDE on an almost daily basis and so reflect data only for the last month. If you want historic data then towards the bottom of the page there is an option where you can select a period and see and download files from that period.
Most months I download the first file above and process it to extract these kinds of statistics in the same sort of way, I guess, as Kaspars Migla who runs the chessratings.top website referenced in the FIDE post in the other answer. If I forget then I download the 3 separate files from the archive. This is obviously more work but the big file isn't available in the archive.
From what Kaspars Migla says:

It is a very rough estimation because only games played by rated players in classical chess are taken into account.

it looks like he just downloads the standard file whereas I download the file with all data including rapid, blitz and Online Arena. So, his figures are likely to be slightly different from mine.
There are a number of things to note.

File 1 (full list of players) is more than sum of files 2, 3, and 4. It contains unrated players and ratings for FIDE's Online Arena.
For each player and rating type, along with the player's rating and K factor, it gives the number of rated games played that player in the period.
Because FIDE update the files more than once during the month you will get slightly different data if you download on different days.
Because these game numbers are for rated games played by a rated player they include each game played between two rated players twice, once for each player.
Similarly, they also include games played between a rated player and a previously unrated player who gains a rating in this period only once. The newly rated player has the game counted in their count, because it was played against a rated player, but the previously rated player doesn't because for them the game was not against a rated player. Hence odd numbers are possible in a sum which is roughly twice the number of rated games played.

How many FIDE rated games are played around the world each year?

OK, so now for the numbers. As I said I download and process the big file for all the players containing all the data rather than the three separate files for standard, rapid and blitz only. I've run some queries on my resulting database.
For each year the four numbers are sum(standard game count), sum(rapid game count), sum(blitz game count), (sum of sums)/2
As explained above the sum(standard game counts) is actually roughly twice the sum of actual FIDE rated games because each game is counted for each player.
As it happens the total number of FIDE rated games did exceed 3 million in 2019 for the first time although just over half were standard and the others were rapid and blitz.
I've given figures going back to 2011, the year before FIDE started rating rapid and blitz.
Year Standard   Rapid   Blitz   Total
2019 3015776    1684486 1338912 3019587
2018 2886482    1382951 1063591 2666512
2017 2786351    1150926 958753  2448015
2016 2629805    907642  785846  2161646
2015 2349963    631590  589853  1785703
2014 2022154    467333  426370  1457928
2013 1873662    313977  338094  1262866
2012 1689346    97722   117587  952327
2011 1569389    0   0   784694


About the Alireza Firouzja vs Magnus Carlsen KN-KN endgame A game between Alireza Firouzj and Magnus Carlsen in chess24’s [Magnus Carlsen invitational 2020](https://chess24.com/en/embed tournament/magnus-carlsen-invitational-2020) ended in a draw due to "insufficient material".

Each player had a king and a knight when it ended

[FEN ""]

 1. e4 e5 2. Nf3 Nc6 3. Bb5 Nf6 4. d3 Bc5 5. Nc3 d6 6. Bg5 h6 7. Bxf6 Qxf6 8. Nd5 Qd8 9. b4 Bb6 10. c3 a6 11. Nxb6 cxb6 12. Bc4 b5 13. Bb3 O-O 14. O-O Qf6 15. Re1 Be6 16. a4 Rac8 17. axb5 axb5 18. Bxe6 Qxe6 19. Qe2 Rfd8 20. h3 d5 21. exd5 Rxd5 22. Rad1 Rcd8 23. Rd2 Qd6 24. Red1 Qg6 25. Ne1 Kh7 26. Nc2 R8d7 27. Ne3 R5d6 28. Nf1 Rd5 29. Qf3 Nd8 30. h4 h5 31. Ng3 Qg4 32. Nxh5 Qxf3 33. gxf3 Ne6 34. Ng3 Nf4 35. Ne4 b6 36. c4 Rd4 37. c5 Rxb4 38. cxb6 Rb7 39. Nd6 Rxb6 40. Nxf7 Ng6 41. h5 Rf4 42. Ng5+ Kh6 43. Ne4 Nh4 44. Kf1 Nxf3 45. Rc2 Kxh5 46. Rc8 b4 47. Ke2 b3 48. Rb1 b2 49. Rc5 Nd4+ 50. Kf1 Nf3 51. Rc2 Rb3 52. Nc5 Nd4 53. Nxb3 Nxc2 54. Rxb2 Ne3+ 55. Ke2 Rxf2+ 56. Kxf2 Nd1+ 57. Kf3 Nxb2 58. Ke4 g5 59. d4 exd4 60. Nxd4 g4 61. Nf3 g3 62. Kf4 g2 63. Kg3 Nd3 64. Kxg2

Reading Checkmate with King and Knight vs King and Knight, it says it is possible for either side to win and should not be declared a draw.

What is the difference?

Source: Game commentary at 12:00 https://www.youtube.com/watch?v=Idw0cgmjWQ8&t=12m

  As it is a draw by insufficient material.

The players agreed on a draw because there is no forced mate. Even if one side loses a knight, it is a draw. The weaker side just has to keep the king in the center.

In the following example Black helped White to achieve mate by playing 4...Ng8??. If Black had played 4...Ng4 it's still an easy draw. Black could have even escaped with 4...Kg8 5.Kxh6 Kf8 and it's easy to draw with Black.

4k3/8/7n/4K3/8/6N1/8/8 w - - 0 1

1. Kf6 Kf8 2. Kg6 Kg8 3. Ne4 Kh8 4. Nd6 Ng8?? (4... Ng4=) 5. Nf7#

In short, they agreed on a draw because no one expected the other party to help him get mate!


How can I do batch analysis of games? I want to run a batch analysis of games and produce output like Lichess computer analysis. I want to do this offline on my desktop PC. Since Stockfish is free, there must exist some solution. Does anyone have any ideas, please?

Lichess provides its source code, so it should be easy to use this code, with minor modifications, with any number of scripts.
Most engines already come with a computer analysis, so writing a program to feed in every position from a pgn file is easily done.
The problem with both is programming skills.  I thought that I could do this, but I gave up even before I found the code related to reading pgn files.  There must be a programmer who would do this just for a challenge, but finding him seems impossible today.  On the other hand, Python claims to be easy to program and already has chess code provided, maybe with a little effort, you could accomplish this yourself.
Sory, this is no help, but, although most currently have the spare time, all consider this not prestige enough to bother.


Prove that White is not allowed to castle here A friend recently gave me the following weird chess problem to solve. I'm afraid that I'm struggling to see the key idea that would ultimately count as proof. From the position, intuitively speaking, it looks like White should be allowed to castle, but I'm sure to be missing something here.
Prove why white is not allowed to castle in this position.
[FEN "1n2k3/p1pqppp1/1p1p1n2/3N2p1/1PB3bP/2P1PN2/1P1P1PP1/2BQK2R w K - 0 1"]

This is actually a rather typical retrograde problem, just start with the most basic observations:

We see that black is missing both rooks and the f8 bishop. Given black's pawn structure it's easy to see that neither the f8 bishop nor the a8 rook could have escaped the structure, thus they must have been captured on the 8th row (by a white knight for example). This leaves us with the h8 rook, for which there's only one plausible choice left, namely having been captured on the b4 square by the a3 pawn.

As for white, the only missing piece is the rook, which must evidently have been captured on the g5 square by the h6 pawn.

Now we arrive at the real question: which rook could have logically been captured first, the one on g5 or the one on b4? Surely if the black h8 rook is to be captured on b4, it must first have been freed by the white rook being in turn captured on g5, but that's impossible, as the h8 rook being taken off on b4 is the very thing that must have freed white's a1 rook in the first place! Which leaves us with one remaining logical possibility: White's h1 rook must have been the one coming out and subsequently captured on g5, which then in turn frees black's h8 rook, to come out and be taken off on b4 by white, which finally freed the a1 rook.

Thus the rook you see currently on h1 is actually the rook coming all
the way from a1 (once freed), with the original h1 rook having been
lost on g5. Given this sequence as the only possible logical sequence
leading up to the current position, white cannot castle, as for
castling to be allowed, neither the king nor the rook must have
moved.

These kinds of puzzles usually go under the category of retrograde analysis, where unlike usual chess puzzles where the intent is to find the best moves/tactics or mates, in retrograde problems it's rather often just a logical question that can be answered by considering the basic rules of the game, and trying to find the only logical sequences (not move by move though, just the necessary ideas) that could have led to the position given in the puzzle. So if you're not familiar with these kinds of problems you may indeed find it difficult to attack them at first. Retrograde problems in chess are really fun to solve, specially as soon as you get the handle of them and start solving the real difficult ones. The solving process is really similar to that of a detective solving a crime, since if you think about it, you're given some clues and trying to figure out what could and could not have happened ;)

Addendum after some comments:
(This is regarding which of the black rooks may have been taken off on b4, although this fact leaves the proof unperturbed.) The a8 rook is trapped on the 8th row, as the only possible way for it to escape the 8th row would be via the h-file, which once opened (i.e white losing the h1 rook on g5) would first let the original h8 rook out. Of course you can always assume the h8 rook and f8 bishop were for example first taken off by a knight, then the a8 rook was the one coming out to get captured on b4 (e.g. Nc6, Qe6, Kd7 to open the 8th row), but for the purpose of the puzzle it won't matter, as in either scenario white wouldn't be able to castle as the same arguments hold.


How to send uci messages from c# app to stockfish on android? I downloaded the binary of Android Stockfish arm64-v8a and looked in the CPP source files. In main() there is all initialization, and then there is UCI::loop(), which catches standard input with getline() and writes back with sync_cout(). How can I write to the engine from a c# (xamarin) application? And is it necessary to make some additional initialization?

I found this,
which could be close to my problem, but maybe it is not. I don't want to spend three days just to see I'm doing complete nonsense.

Also I don't know how to recognize Stockfish's console. Is there only one console, no matter how many different libraries the program can use?

As I don't understand the technical part much, I'm including a screenshot of what I expect to be the Stockfish I should communicate with :-). If it is wrong from the beginning, please let me know.

EDIT: What file type is the stockfish-8-arm64-v8a, is it android native library or native shell executable or something else? Where to put the file, how to set it up (in Visual Studio 2015), how to call it from code? I have some code that I tried here but still I can't make it work.

When you're using C#, you can use any UCI engine in the same manner.  With C# you have to add an event handler to the OutputDataReceived event (and optionally the ErrorDataReceived event).  As a quick example:

ProcessStartInfo si = new ProcessStartInfo() {
    FileName = uciPath,
    UseShellExecute = false,
    CreateNoWindow = true,
    RedirectStandardError = true,
    RedirectStandardInput = true,
    RedirectStandardOutput = true
};

myProcess = new Process();
myProcess.StartInfo = si;
try {
    // throws an exception on win98
    myProcess.PriorityClass = ProcessPriorityClass.BelowNormal;
} catch { }

myProcess.OutputDataReceived += new DataReceivedEventHandler(myProcess_OutputDataReceived);

myProcess.Start();
myProcess.BeginErrorReadLine();
myProcess.BeginOutputReadLine();

SendLine("uci");
SendLine("isready");
SendLine("ucinewgame");

And the methods alluded to above:

    private void SendLine(string command) {
        myProcess.StandardInput.WriteLine(command);
        myProcess.StandardInput.Flush();
    }

    private void myProcess_OutputDataReceived(object sender, DataReceivedEventArgs e) {
        string text = e.Data;
        //Debug.WriteLine("[UCI] " + text);
    }

This is an incredibly simplified example.  In my own code I have a semaphore in order to fully process each output line before moving on to the next one and several semaphores in the UCI start and "isready" handling.

For a full overview of the UCI protocol, check out the specification.


What are good YouTube channels for improving chess? What are good YouTube channels that help to improve our chess?

Channels which are analyzing their own games (Blitz, standard, OTB) or discussing tactics, strategies, etc.

I list some of these channels in the following.

Please share your favorites. Note that here we are interested in channels with learning material not channels with plenty amount of advertisements or fun.

Channels here are ordered arbitrarily with no preferences:

IM Andrew Martin Chess Videos
John Bartholomew
Chess Network
Simon Williams
Chess Club and Scholastic Center of Saint Louis
kingscrusher
GJ_Chess

There are some other channels such as OnlineChessLessons, which are good but they are more introduction to openings. If one wants to go deep into something then have to pay for their videos but a simple blitz game analysis by IM or GM or even a normal good player can give more insight than an introduction to an opening X.

 P.S0: Notice that I'm not looking for good online resources like this question:
Free learning material, also not only for the beginner rather for advanced players.
I want to be strict only on YouTube channels, as the other question does not cover even the channels that I've already subscribed.

ChessExplained is the channel of IM Cristof Sielecki. Most of the videos are him thinking aloud while playing blitz, and they provide excellent insight into the mind of an IM.

IM Greg Shahade has a similar channel as well. He is a bit more entertaining and less instructional than ChessExplained.


Is there a site that provides (legal) online access to free chess books? As the title says, is there a site that provides (legal) online access to free chess books?

Open Chess Books is a site that aims to “republish classic chess books, with all diagrams transformed in animated boards, and release them for free.”

They only have two books at the moment (Modern Ideas in Chess and Chess Fundamentals), but it's a great resource so far.

Predator at the Chessboard by Ward Farnsworth is a great primer on chess tactics that's available to read for free online or purchase in print form.


Why is 7 Bd3 in the Cambridge Springs QGD more often met with 7...Ne4 than 7...dxc4? My question relates the Cambridge Springs QGD when Black deviates from the main line by playing the well-known inaccuracy 7 Bd3.

[FEN "..."]
1. d4 d5 2. c4 e6 3. Nc3 Nf6 4. Bg5 Nbd7 5. e3 c6 6. Nf3 Qa5 7. Bd3

I had always been taught to play 7...dxc4 8 Bxc4 Ne4 here. However, searching an up-to-date database of OTB games I see that of the 292 games to reach the position after 7 Bd3 118 players chose 7...Ne4, while only 97 chose 7...dxc4. Furthermore of the 13 players above 2200 who have got to this position as Black, 8 chose 7...Ne4, 4 chose 7...dxc4, and 1 chose 7...Bb4.

However, I don't understand why this should be. It seems to me 7...Ne4 8 Bxe4 dxe4 9 Ne5 (the usual continuation) White is doing relatively better than they would be doing after 7...dxc4 8 Bxc4 Ne4.

Am I missing something, or is the case that Black players are making a mistake by choosing 7...Ne4 instead of 7...dxc4?

7...dxc4 is absolutely just as good as 7...Ne4. Stockfish 10 (at depth 32) gives 7...dxc4 an evaluation of -0.31, while 7...Ne4 is 0.23. A difference of 118 games vs 96 games isn't a big deal and has very little weight in determining the objective strength of a move. So this is one of those cases where deciding which move to play is a matter of taste.

EDIT - according to online saved results, Stockfish (as of Aug 1 2019) at depth 47 gives 7...dxc4 a -0.43 evaluation. So it's definitely sound :)


Why is 1.e4 c5 2.Nf3 b6 so unpopular? Why is the Sicilian line with 1.e4 c5 2.Nf3 b6 almost never played at any level, nor considered in books and similar? It seems logical to me, and after the usual 3.d4 cxd4 4.Nxd4 Bb7, the Bishop is already well placed on b7 to control key central squares. So are there any obvious faults in this line that I am missing?

 [FEN ""]
 1.e4 c5 2.Nf3 b6 3.d4 cxd4 4.Nxd4 Bb7

It's not that unpopular amongst off-beat lines that can emerge from the Sicilian defense, on top which it has a natural tendency to transpose to Owen defense type of positions.

As to why it's not as popular as Sicilian mainlines, much similar to 1.b3 or 1...b6 openings, 1...c5 2...b6 is not a sound starting setup strategically, for the following summarised reasons:

From opening theory principles:

2...b6 does not contribute to kingside development. King safety in Sicilian structures is of paramount importance as the opening easily leads to very open play where: white's 4 minor pieces are efficiently and centrally developed, central files become semi-open, etc.
2...b6 is not an effective developing move either, that is to say, it does not pose any immediate threats to white. As opposed to e.g. a Dragon Sicilian development (diagram below), where the coordination of knight on c6 and bishop on g7 come with tempo as white has a number of targets on that long diagonal and black's quickly finishing development and will be in time to either create space on the queenside or play the d5 advance. So it being a passive non-effective developing move, it gives free vital play to white.
It resolves the address of your king, as the early b6-c5 setup makes it very unlikely for black to castle queenside, and that's useful information for white! And generally, the reason why kingside fianchettos tend to be stronger and more important early on than queenside ones, is because the structure provides a good fortress for the king!

(Diagram for 2nd point)

 [title "Dragon Sicilian example"]
 [fen ""]

 1.e4 c5 2.Nf3 Nc6 3.d4 cxd4 4.Nxd4 g6 5.Nc3 Bg7

From a Sicilian opening theory point of view

2...b6 is inconsistent with what the Sicilian defense aims to achieve: The Sicilian, unlike the French defense, it is an active type of defense where black aims to claim their own share of central space control, not immediately challenging white's light square control (provided with 1.e4) but instead, focusing their play more on the dark squares. With this in mind, it is clear that b6-Bb7 are not assisting black's cause in dark square control.
b6-c5 setup tends to be a decent structure when the c5 pawn cannot easily be challenged, much like the white pawn setup in English or 1.b3 type openings with b3-c4-e3 or c4-d3-g3. But as you yourself pointed out, d4 advance is happening immediately for white and black's forced to capture at once as to not provide white with the complete control of the sweet centre.
1...c5 is already a queenside, non-central-pawn commitment, but its aim is justified as it offers to trade a non-central c pawn for white's important central d2 pawn. But 2...b6 has no such immediate justification, it's a move away from the centre, and by itself does not provide control over any important squares.
The latter point is really important when dealing with Sicilian: as it stands, even in the mainlines, white always has the lead in both development and central control and black is always playing catch-up at best. So b6 in that sense is really putting black even further behind in development. Again as explained earlier, the light square control that Bb7 provides is really of minimal relevance for black at the beginning considering white's natural setup in the Sicilian.
All the last couple of points translate into: the later your knights can be centrally developed, the later your castling is prepared, the more difficult you are going to find it to create any threats against white to balance the game. And playing a Sicilian defense, you have to be able to create threats, or at least have strong prospects in doing so. These are fundamentally different from an opening like the Caro or French. For inspiration, I highly encourage you to study the following game by Kasparov, which truly epitomises the kind of play the Sicilian opening aims to achieve.

(note the very early pawn sacrifice to resolve the Moraczy bind, and the active piece development that follows after d5, gradually taking more and more options from white, no tempo is wasted on a slow non-developing move)

 [title "Karpov - Kasparov 1985 match game 16"]
 [fen ""]

 1.e4 c5 2.Nf3 e6 3.d4 cxd4 4.Nxd4 Nc6 5.Nb5 d6 6.c4 Nf6 7.N1c3 a6 8.Na3 d5 9.cxd5 exd5 10.exd5 Nb4 11.Be2 Bc5 12.O-O O-O 13.Bf3 Bf5 14.Bg5 Re8 15.Qd2 b5 16.Rad1 Nd3 17.Nab1 h6 18.Bh4 b4 19.Na4 Bd6 20.Bg3 Rc8 21.b3 g5 22.Bxd6 Qxd6 23.g3 Nd7 24.Bg2 Qf6 25.a3 a5 26.axb4 axb4 27.Qa2 Bg6 28.d6 g4 29.Qd2 Kg7 30.f3 Qxd6 31.fxg4 Qd4+ 32.Kh1 Nf6 33.Rf4 Ne4 34.Qxd3 Nf2+ 35.Rxf2 Bxd3 36.Rfd2 Qe3 37.Rxd3 Rc1 38.Nb2 Qf2 39.Nd2 Rxd1+ 40.Nxd1 Re1+ 0-1

Last but not least, here's one possible continuation for c5-b6 which is cherry-picked to emphasise how quickly it can go wrong for black as they are behind in every aspect of development:

[title "Concrete example"]
[fen ""]

1. e4 c5 2. Nf3 b6 3. d4 cxd4 4. Nxd4 Bb7 5. Nc3 Nf6 6. e5 Nd5 7. Nxd5 Bxd5 8. Nb5 Bb7 9. Bg5 Qc8 (9...h6 10. Nd6+) (9...d6 10. Nxd6+) 10. Qe2 e6 11.O-O-O


Why is white in trouble in the following endgame? Playing white against my computer I ended up in the following position (with white to move).  To me it looked about even, but no matter what I tried I kept losing the position, and indeed stockfish rates the position around -1.  What exactly is bad about white's position here?

[FEN "5k2/pppb1pp1/5p2/3Pn3/4B3/2P2N2/P1P3PP/6K1 w - - 0 1"]

What's bad for White in this position is that his structure is already slightly worse (isolated a-pawn), and that Black can worsen it further. White's advanced d-pawn is actually a liability that Black can readily attack by bringing her king forward. The pawn will prove difficult to defend, and at the very least Black can basically force White to accept being saddled with two isolated c-pawns as well by playing ...c6 at some point (when the alternative would be to lose a pawn straightaway on d5).

Is this enough to mean that White is necessarily lost? Probably not (though I certainly wouldn't fancy trying to hold it against a strong engine). But the point is that Black doesn't have similar structural weaknesses, and so she doesn't have the same natural targets to deal with (her doubled pawns aren't nearly the liability that White's are), while White will be forced to keep an eye guarding his queenside. To my mind, this is enough to explain Stockfish preferring Black.

Unfortunately we don't have inline annotations active for the site's PGN viewer, so I will let the verbal explanation already given suffice, and provide just a handful of variations illustrating the points given.

[fen "5k2/pppb1pp1/5p2/3Pn3/4B3/2P2N2/P1P3PP/6K1 w - - 0 1"]

1.Kf2
    ( 1.Nd2 Ke7 2.c4 f5 3.Bd3
        ( 3.Bf3 Kd6 4.Kf2 Ba4 5.c3 c6 6.dxc6 Bxc6 )
    3...c6 4.dxc6 Nxc6 )
1...Ke7 2.Ke3 Kd6 3.Kd4 c5+ $1 4.dxc6
    ( 4.Ke3 $2 Ng4+ 5.Kd2 f5 6.Bd3 Kxd5 )
4...Nxc6+ *


Chess move generation with bit boards in Javascript To make my engine more efficient, I am writing my engine such that it uses bit-boards in its move generation. But I have a question, suppose I have a rook move mask centered at a specific spot, how might I transpose the rook mask so that it shows the moves for a different position? eg:

from this mask:
[
    [0, 0, 0, 1, 0, 0, 0, 0],
    [0, 0, 0, 1, 0, 0, 0, 0],
    [0, 0, 0, 1, 0, 0, 0, 0],
    [0, 0, 0, 1, 0, 0, 0, 0],
    [1, 1, 1, "R", 1, 1, 1, 1],
    [0, 0, 0, 1, 0, 0, 0, 0],
    [0, 0, 0, 1, 0, 0, 0, 0],
    [0, 0, 0, 1, 0, 0, 0, 0]
];

to this mask:
[
    [0, 0, 0, 1, 0, 0, 0, 0],
    [0, 0, 0, 1, 0, 0, 0, 0],
    [0, 0, 0, 1, 0, 0, 0, 0],
    [0, 0, 0, 1, 0, 0, 0, 0],
    [0, 0, 0, 1, 0, 0, 0, 0],
    [1, 1, 1, "R", 1, 1, 1, 1],
    [0, 0, 0, 1, 0, 0, 0, 0],
    [0, 0, 0, 1, 0, 0, 0, 0]
];

If you need any clarifications regarding the question feel free to ask.

In the beginning, they thought that using a right shift (or a left shift), but they found that, as with other systems, bit would fall off the board.  To correct this, they computed every move from each square for each piece.  This takes a performance hit only when the page loads.  The other alternative they tried was to just load precomputed bitboards which increases the data slightly.

I've developed a system which has drawbacks including being slightly slower, but it's easier to understand.

First you need three arrays:

const int movement[64] ={

17171, 50075, 50075, 50075, 50075, 50075, 33179, 32905,

18231, 51199, 59391, 59391, 59391, 59391, 41471, 41165,

20279, 57343, 65535, 65535, 65535, 65535, 45567, 45261,

20279, 57343, 65535, 65535, 65535, 65535, 45567, 45261,

20279, 57343, 65535, 65535, 65535, 65535, 45567, 45261,

20279, 57343, 65535, 65535, 65535, 65535, 45567, 45261,

20023, 24319, 32511, 32511, 32511, 32511, 14591, 12493,

 3110, 23662, 15470, 15470, 15470, 15470, 14446, 12364

};

const int dir[16] ={
    8, 1, -8, -1, 9, -7, -9, 7, 17, 10, -6, -15, -17, -10, 6, 15
};

const int key[16] = {
    1, 2, 4, 8, 16, 32, 64, 128,
    256, 512, 1024, 2048, 4096, 8192, 16384, 32768
};

This is constructed so that if the first bit (key[0]) is set, then the relative movement of +8 (dir[0]) is possible;  (Showing this in hex would display the relative values better.)

The move generation is six functions each containing about 9 lines each.  The bitboard generation is shorter and faster, but harder to implement.  Using magic bitboards is even faster, but it's even harder to understand.


What does "bxa1=Q" mean? I have a PGN file with the following move in it:

  fxe5 bxa1=Q

I understand the equals sign represents a draw offer, but what does "=Q" mean?

I would read it as "Pawn takes something on a1 and promotes to a Queen".

Strictly according to the Laws of Chess the = sign should not be there (see article C.11).

  C.11
  In the case of the promotion of a pawn, the actual pawn move is indicated, followed immediately by the abbreviation of the new piece. Examples: d8Q, exf8N, b1B, g1R.

However this is a PGN file, which has its own rules for game notation and it uses the = sign for pawn promotion (see paragraph 3 of article 8.2.3.3 in the PGN standard specification also available here, which should probably be the official reference).

  [...]. Pawn promotions are denoted by the equal sign "=" immediately following the destination square with a promoted piece letter (indicating one of knight, bishop, rook, or queen) immediately following the equal sign. As above, the piece letter is in uppercase.

Draw data is handled in so-called  EPD records for describing chess positions, using verbose opcodes like draw_offer.  Although it isn't included in PGN proper, specifics are included in articles 16.2.5.8 - 16.2.5.11 of the standard.


Numerical FEN writing What is the most compressed way to "write" a chessboard as an integer considering en passant and castling as always possible no matter what.

If all the pieces are on the board, there are 64!/32!/8!^2/2^6*(32/63)*(31/61) or about 1.2*10^42 positions.  This would require 140 bits.  The 64!/32! puts the pieces on squares, the divisions account for permuting like pieces, and the last two fractions put the bishop pairs on opposite color squares.  I would guess a dozen or so more bits would be required to cover positions with some of the pieces gone, but calculating the exact number is not so easy.  Decoding a position from 140 bits can be done, but would be a pain.  Clearly 8 bytes will not suffice.


Making the best use of a coach? Currently I pay for lessons, and I surely see value. I've gotten from the low 600s to being able to give USCF 1200s a run for their money. It's not much, but it makes me pretty happy.

But I feel like a lot of coaching sometimes is just random topics with a lack of structure. I usually bring 5-7 games to my coach and we go over them, followed by extra things I should study to improve my weaknesses. I also bring up stuff I have read, for example in How to Reassess your Chess to get clarification.

Is there anything more I can do to better utilize my coach?

Thanks!

I think you are making good use of your coach from the sound of it.  Perhaps you are not studying the correct books for your rating.  And you should be heavy on puzzles and basic endgames; if your coach hasn't pushed you toward that there may be reason for concern.


App that identifies moves as Excellent/Good/Mistakes/Blunders I really like the analysis tool on chess.com that processes your games and identifies the Excellent and Good moves, as well as Mistakes and Blunders. It also proposes which move should have been played.

I realize it's probably based on a drop or increase in your piece advantage, but I really like this tool since I can clearly see what were my opponent's blunders or mistakes (as well as mine).

Is there an Android app that has similar features? The chess.com app allows me to analyse my chess.com games, but not to import a PNG and process it. Other analysis apps I've seen only return the "piece advantage score".

I would suggest starting at lichess.org. It has tools that let you (1) analyze a game that you play on the site or (2) import a game and analyze it.

The lichess.org analysis includes inaccuracies, mistakes, and blunders. It does not have excellent or brilliancy (! or !!) markers, but they provide a rationale for why they don't use those. You can decide whether their explanation suffices for your purposes. They use a centipawns lost or gained graph that seems to be a good indicator of the game state. And they often suggest better moves with the corresponding alternate lines.

They have an Android app at https://en.lichess.org/mobile that you can try out to see if it meets your needs. You can also try out their web site on a mobile device to see how that works, too.

Finally, what I like about lichess.org is that they seem to have a great interest in having a clean, stylish piece and game user interface and they also seem to be actively developing, so if you have suggestions they may take a listen.

EDIT: Somehow I neglected to mention earlier that the site is free and the code is open source. Both are great if you want to save some money while learning chess and even possibly get interested in seeing how the site code works.


Find opening names from fen online query I have the fen(arbitrary), I would like to get the completely opening names for the move list by passing the fen to the site. Are there any sites like this that are pretty exhaustive and free? It could simply return the last opening name as I could query it manually but this requires more work than I'd like to do.
Every site I have is some downloadable database or has an interface for searching through openings. I'd like something I could just get the names in json, html or some other text that correspond to the fen moves ordering. I'd rather not have to try and hack up some site to try and extract the info.

I appreciate that this is not a complete answer to your request but one potential solution would be to download and use a local copy of my free open source pgn-extract program and use options along the following lines:
pgn-extract --fenpattern "r1bqkb1r/pppp1ppp/2n2n2/4p3/2P5/2N2N2/PP1PPPPP/R1BQKB1R w KQkq" eco.pgn

The program comes with the file eco.pgn that contains ECO codes and opening names so the above outputs all the matches in eco.pgn for openings that reach the given FEN position, for instance:
[Event "?"]
[Site "?"]
[Date "????.??.??"]
[Round "?"]
[White "?"]
[Black "?"]
[Result "*"]
[ECO "A28"]
[Opening "English"]
[Variation "four knights, Romanishin variation"]

1. c4 e5 2. Nc3 Nc6 3. Nf3 Nf6 4. e3 Bb4 5. Qc2 Bxc3 *

along with another 9 possibilities.


What is the name of chess format in which one player has only pawns, no king? I remember watching some games on youtube in this weird format but forgot what it's called.
One player has only pawns (lots of them. no other pieces, not even king) and has to achieve mate. Other player has to capture all of opponent's pawns to win the game.

It is either Horde or the very similar Dunsany's chess: 32 pawns against the regular chess army.


How to use a Polyglot book in C# with a chess engine I would like, if possible, for someone to provide a code snippet of a basic logic to access a Polyglot book file. I'm having trouble finding the file format documentation, so I don't know how to access it and use it in the code. I'm making a chess game and would like to use the books to support features in the game. If not too much trouble, I would rather have a c# code sample, since it's the language I'm fluent with right now.

Sorry, I don't have C# code. Can we do it in C++?

https://github.com/Warpten/Fruit-2.1/blob/master/src/book.cpp

Polyglot book is defined like:

struct entry_t {
   uint64 key;
   uint16 move;
   uint16 count;
   uint16 n;
   uint16 sum;
};

You may want to wrap the C++ code inside your C#. How to do that is out of scope here.


Interesting Ending Knight + pawn vs Rook - main plans (white and black) From the feedback received I updated the main line (from pos 39). I post an update of this endgame. Now it is more clear that f7 is a weak point, and it is tricky for black to try to stop the two menaces: f7 and play on the c file ... It is not clear whether to try to take e5 pawn or play on the queenside without stopping rook menaces.

Edit 1: From your suggestions I tried to improve the game ... but somehow I think that white can improve the game ... I arrive at this position that seems nice for black (with idea of b3 and promote ...)

[Title "Side to move: Black"]
[StartFlipped "0"]
[fen "8/5p2/4p2p/3pP1pP/1p1n4/k7/P2R1KP1/8 b - - 5 45"]

Here I post the update the rest of analysis :

[Event "Android 2.3.5"]
[Site "GT-I9001"]
[Date "2015.04.20"]
[Round "-"]
[White "Stockfish 4"]
[Black "Mandor"]
[Result "*"]
[Startply "75"]
[fen ""]

1.e4 e6 2.d4 d5 3.Nc3 Nf6 4.e5 Nfd7 5.Nce2 c5 6.c3 Nc6 7.f4 Qb6 8.Nf3 cxd4 9.cxd4 Be7 10.Nc3 O-O 11.Be2 a6 12.O-O Qa7 13.Be3 b5 14.Qc2 Nb6 15.b3 b4 16.Nb5 Qd7 17.Nd6 Bxd6 18.exd6 Qxd6 19.Ne5 Ne7 20.Bd3 g6 21.Rac1 a5 22.Qc5 Qxc5 23.dxc5 Nd7 24.c6 Nxe5 25.fxe5 Ba6 26.Bxa6 Rxa6 27.Bc5 Nxc6 28.Bxf8 Kxf8 29.Rfe1 Ke7 30.Rc2 Kd7 31.Rf2 Nd8 32.Kf1 Rc6 33.Ke2 Rc2+ 34.Kf1 Rxf2+ 35.Kxf2 Nc6 36.h3 Kc7 37.h4 Kb6 38.Kf3 h6 39.Kg4 Kb5 40.Kg3 a4 41.bxa4+ Kxa4 42.h5 g5 43.Re2 Ka3 44.Kf2 Nd4 45.Rd2 b3 46.axb3 Nc6 47.Ke3 Kb4 48. Rc2 Kb5 49.Rc1 Nxe5 50.Rc7 Kb6 51.Re7 Kc6 52.b4 Kd6 53.Rb7 Ng4+ 54.Kd4 e5+ 55.Kc3 d4+ 56.Kc4 Ne3+ 57.Kd3 Nxg2 *

All suggestions are welcome! Thanks!

Edit 2:
From this position : 8/5p1p/1kn1p1p1/p2pP3/1p5P/1P3K2/P5P1/4R3 b - - 2 38

Summarizing until now from the core position. Is it possible to win with black? How? :)
1) Plan put Knight on f6 seems to fail due to: 38. Kf3 (for example) .. Nd4+ 39. Kf4 Nb5 40. Rf1! (and ok Knight, you can occupy f6 and I will let rook take f7 for example with Ke3 )

2) Plan to change e5 pawn for f7 pawn I did not manage to have anything. Usually the white rook could counter attack on the back rank, and somehow the king and rook will take the kingside pawns.

3) Plan to put king on b5 for me seems the most promising... but I did not manage to make it work : 38. Kf3 (to be coherent) h6 39. Kg4 (yes seems strange) Kb5 40. Kf4 a4 (with initial idea but ..) 41. bxa4+ Kxa4 42. Rc1! .. and what to do? Kb5 ?¿ And how to progress ? :(  (I though something like 42. Rc1 42. g5 43. hxg5 hxg5 44. Kxg5 Nxe5 45. Kf6 ...

Other ideas?¿

First of all, I think white can only play to hold. The question is whether black can really create winning chances.

All the h3-h4-Kf3-Kg4-Kg3 stuff in the game and your line, is pretty much just white doing nothing.

Personally I would put the king on f4 straight away to free up the rook. And then put the rook on the c-file. This should limit blacks options by attacking the knight, cutting off the king and threatening a backrank invasion should the knight ever move.

In this scenario even playing a4 cannot easily be engineered because the black king wouldn't be able to take back on a4 and keep protecting the knight.

There are some other motifs in this position. When the white king reaches f4, black pretty much has to play h6 to prevent the invasion. And if black plays h6 white has to play h4, otherwise g5+ will always threaten to win the e5 pawn. If white starts with h4, I would seriously consider h6 with black because white might play h5 the next move, and suddenly the black kingside becomes pretty morose. (So, in the line you give 37.h4 Kb6 38. h5 might be an idea for white. 38…g5 39.h6 and the g5 pawn will fall, 38…h6 39.hxg6 fxg6 and at least there is another open file, although that one isn't so clear to me, but still, why give white the option?)

[FEN ""]
[Startply "75"]
[Event "Android 2.3.5"]
[Site "GT-I9001"]
[Date "2015.04.20"]
[Round "-"]
[White "Stockfish 4"]
[Black "Mandor"]
[Result "*"]

1.e4 e6 2.d4 d5 3.Nc3 Nf6 4.e5 Nfd7 5.Nce2 c5 6.c3 Nc6 7.f4 Qb6 8.Nf3 cxd4
9.cxd4 Be7 10.Nc3 O-O 11.Be2 a6 12.O-O Qa7 13.Be3 b5 14.Qc2 Nb6 15.b3 b4
16.Nb5 Qd7 17.Nd6 Bxd6 18.exd6 Qxd6 19.Ne5 Ne7 20.Bd3 g6 21.Rac1 a5 22.Qc5
Qxc5 23.dxc5 Nd7 24.c6 Nxe5 25.fxe5 Ba6 26.Bxa6 Rxa6 27.Bc5 Nxc6 28.Bxf8
Kxf8 29.Rfe1 Ke7 30.Rc2 Kd7 31.Rf2 Nd8 32.Kf1 Rc6 33.Ke2 Rc2+
34.Kf1 Rxf2+ 35.Kxf2 Nc6 36.h4 Kc7 37.Kf3 Kb6 38.Kf4 h6 39.Rc1

Now, black can still play for a win, by bringing the knight to c3. For example 39…Nd4 40.Rc8 Ne2+ 41.Ke3 Nc3 42.Rf8 this is extremely sharp and there are many options. White could go 39.Re2 first and the Rc2 and try to defend passively. Or maybe after 41…Nc3 he could just check the black king from behind and only go to f8 after the white kind went to the seven's …


If you exploit Article 12.9 in FIDE's Laws of Chess, is it possible to benefit yourself by purposely receiving a penalty? After I received this answer on my previous question, I found the list of penalties which a player can receive, according to FIDE guidelines.
As FIDE states in Article 12.9:

Options available to the arbiter concerning penalties:

warning
increasing the remaining time of the opponent
reducing the remaining time of the offending player
increasing the points scored in the game by the opponent to the maximum available for that game
reducing the points scored in the game by the offending person
declaring the game to be lost by the offending player (the arbiter shall also decide the opponent’s score)
a fine announced in advance
expulsion from the competition.

I'm curious: Is there potentially a way to benefit yourself by being penalized?
As an example, the second penalty listed is:
2. increasing the remaining time of the opponent
Even if it won't directly add to my time, I can still ponder my moves during the opponent's turn. This would allow me more time to think than I could have otherwise had.
Additionally, are there other ways to benefit yourself by purposely receiving a penalty?

It is important to realize that chess is a zero-sum game*. In other words, everything that gives advantage to one player gives an equal disadvantage to the other player. So if adding 2 minutes to your opponent's clock benefits you, then it would be harmful to your opponent. It is not possible for any decision of the arbiter to give an advantage to your opponent and a slight advantage to you too.

(* Although of course there are things that make both players enjoy the game more etc., but here I'm concerned only about the result of the game.)

Suppose two minutes are added to your opponent's clock. Now (s)he has two choices (or something between them):

Pretend his extra two minutes didn't exist and play as if his clock showed 2 minutes less.
Make good use of his extra time.

If your opponent chooses option 1, the only effect of the extra time is that he does not run out of time accidentally. This never gives any advantage to you. If your opponent thinks that option 2 is better for him than option 1, then he also believes that him choosing option 2 is worse for you.

It is possible that your opponent does not understand how well you use his time and therefore chooses option 2 but it ends up being beneficial to you. However, I think this is very unlikely.

I think a more important loophole is this: When calling the arbiter to settle any dispute over the board, you are allowed to stop the clock even if it is your turn. Sometimes it can take a minute or two before the arbiter arrives, so it can be used as a way to gain extra thinking time. For example, in a difficult position in time trouble, you can claim a draw (even if you know there's no draw) and gain extra time while waiting for the arbiter.

Because the usual penalty for unreasonable claims is adding time to your opponent's clock, you may gain more advantage by the extra thinking time than you lose by the penalty. Needless to say, this is extremely unsportsmanlike, and will result in everyone hating you and possibly even point losses if the arbiter sees through it. Please don't ever do this.


White to play and win I don't normally post puzzles but this one is particularly beautiful
[title "White to move and win"]
[fen "1rR2b1r/3n1k1p/p4npP/1p1q1p2/1R6/BPp2N2/4QPP1/7K w - - 0 1"]


Are there any symmetric zugzwang positions? Although very unlikely, the starting position could be a forced win for Black. This would mean it is a position of mutual zugzwang, in the strong sense that whoever moves first loses. Wikipedia refers to one such position as trébuchet. Such positions are rare, and it would be a big surprise if the starting position was one of them.
The starting position has another property in that it is symmetric. White and Black have exactly the same possible moves (when written in descriptive notation). Are there any symmetric positions that are known to be a mutual zugzwang?

You can easily construct many such positions. For instance:

4k3/8/3P1P/8/8/3p1p2/8/4K3 w - - 0 1

First to move loses - either by moving a king and allowing the opponent to promote or by losing one (and subsequently next) pawn.


What are good UCI-compatible GUIs for Mac? Is anyone running a UCI-compatible GUI on a Mac?  Preferably something native and modern, so WINE and Rosetta (etc) are not needed.  My goal is to simply set up chess positions and let Stockfish analyze.

Any suggestions would be appreciated.

Wow, I usually wouldn't add another answer like this, but I've been quite impressed by the fork of Scid called Scid vs PC (which is more actively maintained, and has a mac distribution called Scid vs Mac). I found it while looking for mac build instructions for Scid while trying to make scid do a better job of processing stockfish's input. (and by the way, Scid vs PC doesn't fix the stockfish 2.2+ problem, as it still depends on the tcl one line at a time input parsing).


Differences between FEN and EPD? I just read the description of FEN (Forsyth–Edwards Notation) and EPD (Extended Position Description), I have a basic idea of what they are, but I still have some points that are not entirely clear:

What are the main differences between those two?
When should I use one over the other one?
Which one is more common to see?

I am trying to decide which one to use for a personal project, and I can't take this jump without knowing everything about them.

What are the main differences between the two?

  Extended Position Description is a standard for describing chess
  positions along with an extended set of structured attribute values
  using the ASCII (American Standard Code for Information Interchange)
  character set. It is intended for data and command interchange among
  chess playing programs. It is also intended for the representation of
  portable opening library repositories. The first four fields of the
  EPD specification are the same as the first four fields of the closely
  related FEN specification. Like FEN, EPD can also be used for general
  position description. However, unlike FEN, EPD is designed to be
  expandable by the addition of new operations that provide new
  functionality as needs arise. More information can be found at this site.

When should I use one over the other one?

  EPD is more expandable by the additon of new operations and is more
  versatile and is used primarily in chess programs.  See bullet point one.

Which one is more common to see?

  Overall, I would say FEN is more common, but this is relative to what you are trying to do.


Checkmating with two bishops Let White have the two bishops.  Given any setup, has the maximum number of moves to forced mate been calculated on an nxn board (for large enough n)?  If not, are there any bounds on this number?
Of course, information on extensions of this problem to say any rectangular board, are also welcome.
I should note that for a 2xn board checkmate isn't possible.  Also, for m >= 3, with n >= m without loss of generality,  I'm not certain whether forced mate is always possible.  I would say though that it is given m,n sufficiently large though.
To update let the bishops be on opposite colored squares, of course.
Update again:  I noticed someone edited the question out.  It isn't meant merely for the 8x8 board, but for any nxn board, where n is any sufficiently large natural number.  I know R&K vs K has been solved in this way for any nxn board.  I'm wondering whether the same has been done for K BB vs. K on any nxn board.  Please watch what you edit next time.  Also, an answer has been accepted to the edited question, not my intended question.

Mate could be forced sooner...[the] two bishops [can mate in up to] 19 [moves].

Source: Last paragraph from Daniel's answer to 'With only a king left, how many moves remaining until a draw?', with editing from me, seeing as I am taking just the part relevant to this question.

For a table of maximum number of moves to mate, see Wikipedia, which cites Batsford Chess Endings by Speelman, Tisdall and Wade.


If given infinite processing power, is there an algorithm that would play chess perfectly? Does there exist such an algorithm where, if given infinite processing power, a computer could play chess perfectly, i.e., it can generate perfect moves from any position?
If so, where can I find the pseudo-code for it?

Does an algorithm exist?  Yes.  According to Zermelo's Theorem, there are three possibilities for a finite deterministic perfect-information two-player game such as chess: either the first player has a winning strategy, or the second player has a winning strategy, or either player can force a draw.  We don't (yet) know which it is for chess.  (Checkers, on the other hand, has been solved: either player can force a draw.)
Conceptually, the algorithm is quite simple: construct a complete game tree, analyze the leaf nodes (the game-ending positions), and either make the winning initial move, resign (if the opponent has a forced win), or offer a draw (if the position is a draw).
The problem lies in the details: there are approximately 1043 possible positions, and an even larger number of moves (most positions can be reached in more than one way).  You really need your infinitely-powerful computer to take advantage of this, since a computer that can take advantage of this algorithm either can't fit in the known universe, or won't finish computation until sometime after the universe ends.


Continuation for white in the Bishops opening variation: 1.e4 e5 2. Bc4 Nf6 3. d4 exd4 4. Nf3 Nxe4 5. Qxd4 Nf6 I am currently reading Chess Openings: Theory and Practice - I.A Horowitz. The first opening displayed in the book is a variation of the bishops opening: 1. e4 e5 2. Bc4 Nf6 3. d4 exd4 4. Nf3. Seemingly the best continuation for black, if they can defend properly, is to continue 4 ... Nxe4 and to 5. Qxd4 respond with 5 ... Nf6.
From this point Horowitz goes on to consider the variation 6. Bg5 Be7 7. Nc3 c6:
rnbqk2r/pp1pbppp/2p2n2/6B1/2BQ4/2N2N2/PPP2PPP/R3K2R w KQkq - 0 8

This seems fine for white (to me) by basic chess principles (good development, castling around the corner). However I have two questions:

What if black had responded with 6 ... Qe7+?
It seems like white either trade queens and is worse or moves the king allowing Nc6 and is just worse?

What can white do after 5 ... Nf6? My thinking is that 6. Bg5 is the mistake so perhaps 6. Nc3.

Using Caissabase or the lichess masters database we can see that instead of Nxe4, Nc6 is more popular to avoid this gambit idea (the Urusov gambit) which is.... dubious but not so simple and seemingly scores fine enough. White has additionally scored p decently.
Qe7+ has only been played in one game, but seems good (black won that game, and SF12 gives -0.89 at depth 37, which is quite good). Nc6 and Be7 are both fine, but Nc6 is probably slightly better, judging from the fact that the lichess database shows it as most common with quite a hefty advantage for black, as opposed to the noticeably higher win rate for white (seemingly due to this very variation, as it turns out!). SF also likes Nc6 best, with an evaluation of -0.86 at depth 40.
After Nf6, Nc3 is seemingly more popular nowadays (as the lichess masters database), but has worse results.
My recommendation would be to consider not playing this gambit in the first place, since the Urusov Gambit is somewhat iffy, although it's probably still playable at a sub-master level, or to get a more recent book on this. This book is from the 1960s, as @Scounged very nicely pointed out, and as such is almost entirely useless- the only cases where it's useful are for general plans and opening names, and even here it will be severely lacking. If you want a starting opening book, Fundamental Chess Openings by Paul van der Sterren is great, although again note that many of the lines will be incorrect (esp in theoretical openings e.g. e4 e5 or the Sicilian)- focus instead on plans and names, and supplement with other sources (books, videos, courses).


Checkmating the bare king with 3 knights – can the mate be forced on any edge square? In the case where White has King and 3 Knights, and Black has just the bare King, it is known that White can force checkmate. But can White in fact pick any edge square in advance, and force the checkmate to occur with the black King on that square? For example, can White guarantee checkmating on e8, if he so chooses?

There's an answer to a related 3 Knights post

mentioning "side mate" as opposed to "corner mate", without going further into it.
In the given example the bare king is not obliged to go to the non-corner edge square where the mate occurs.

Edit after answer accepting
The question is answered in the positive: Any edge square can be chosen to become the mate square.

Here's how to forcibly checkmate the bare King on f8 or e8
(added later: or on g8 or h8) once it's been cornered on h8.
First put Kg6 and Nd7, so the other Knights can roam freely
as long as they don't accidentally checkmate or stalemate
the cornered King; then:

[Title "h8 to f8 (or g8 or h8)"]
[Fen "7k/3N4/2N3K1/4N3/8/8/8/8 w - - 0 0"]

1. Nf7+
(1. Kh6 Kg8 2. Ne7+ Kh8 3. Nf7#) Kg8
2. Nde5 (2. Ne7#) Kf8
3. Kh7 Ke8
4. Nd6+ Kf8
5. Nd7#
(5. Ng6#)

and likewise:

[Title "h8 to e8"]
[Fen "7k/3N4/2N3K1/4N3/8/8/8/8 w - - 0 0"]

1. Nf7+ Kg8
2. Nde5 Kf8
3. Nh6 Ke8
4. Nf5 Kf8
5. Nfe7 Ke8
6. Nd5 Kf8
7. Nce7 Ke8
8. Kg7 Kd8
9. Kg8 Ke8
10. Nc8 Kd8
11. Ncb6 Ke8
12. Kg7 Kd8
13. Nc6+ Ke8
14. Nc7# (14. Nf6#)

To answer the question Glorfindel asks in a comment:
White can start the same way, then set up the Knights on c5/d5/e5
to form a gauntlet and use the wK to push bK to the a8 corner:

[Title "h8 to a8"]
[Fen "7k/3N4/2N3K1/4N3/8/8/8/8 w - - 0 0"]

1. Nf7+ Kg8
2. Nde5 Kf8
3. Nh6 Ke8
4. Nf5 Kf8
5. Nfe7 Ke8
6. Nd5 Kf8
7. Kh7 Ke8
8. Nd4 Kd8
9. Ne6+ Ke8 (9... Kc8 10. Nc5)
10. Nc5 Kf8
11. Kh8 Ke8
12. Kg8 Kd8
13. Kf8 Kc8
14. Ke8 Kb8
15. Kd8 Ka7
16. Kc7 Ka8
17. Nb4 (17. Kb6 Kb8 18. Ne7)

and then use the previous analysis to force mate on any of a5/a6/a7/a8
(or b8/c8/d8), or push the King further to a1, etc.  So once the lone King
has been securely cornered it can be checkmated on any prescribed square
on the board's edge.


Tips for the Najdorf Sicilian? So in the last 2 or 3 games I've played, I've used the Najdorf variation of the Sicilian. It's worked alright in the games, and I was wondering if you guys have any tips that I could use to improve my effectiveness with the Sicilian.

Two or three games is very little to say much. You will not even have encountered all of the main lines after ....a6. Generally the Najdorf Sicilian is rather tactical and opening mistakes can quickly lead to a loss. In some lines white has a very straightforward plan of pushing its h and g pawns and checkmating black.

Practising tactics and studying the opening thoroughly is essential.
For more useful advice it would help to know your playing strength and to see one of your games


Does USCF still pay for the FIDE Master application fee? There is not much to add to the question. Quite simply, does USCF still pay for the FIDE Master application fee?

Per Chris Bird, the USCF's "FIDE Events Manager", the USCF only pays for GM, IM, WGM, and WIM titles. FM(WFM) and CM(WCM) are the responsibility of the player. The USCF still applies on your behalf, but you pay the fee.

The fees are currently as follows:

Grandmaster/WGM: 330 Euro

International Master/WIM: 165 Euro

FIDE Master/WFM: 70 Euro

Candidate Master/WCM: 50 Euro


Alekhine's Defense variation, understanding white's overextended pawns, black's multiple early knight moves I'm a casual, semi-serious chess player and have been an active player for over 10 years. In my time playing, one of the most unusual openings I have had the pleasure of playing against is known as Alekhine's Defense:

[FEN ""]

1.e4 Nf6 2.e5 Nd5 3.d4

In the above line I gave the usual move 3.d4. This seems like a very good position for white, and an underdeveloped position for black. I am, however, more interested in the less common variation 3. c4:

[FEN ""]

1.e4 Nf6 2.e5 Nd5 3.c4 Nb6

which is my usual line of play. From my perspective, the aggressive 3.c4 seems like a better move, buying a pawn development move with a tempo (the pawn at c4 is defended by the white bishop after the response 4...Nb6.) In fact, there are over 300 tournament games along this line of play, indicating better chances for white in the final position above.

I have read in chess literature that if an attacking player is not careful with Alekhine's Defense, he may easily overextend his pawn structure, one of the subtleties of this particular openings. I'd like to know if the last variation I described above is already considered an overextended pawn structure, if so why, and if not, what must white be wary of in order to avoid overextending.

Furthermore, what does black hope to accomplish by placing his knight in peril so many times? Does the fact that white must overextend himself slightly in order to chase the knight multiple times outweigh the opportunity cost of moving the same knight 4 times in the first 4 moves?

In short, white may well be overextending.

From black's point of view¹, white is offering many targets for black to attack :

d4 as c3 is not possible anymore, and if e5 is traded for d6.
e5 if d6 gets traded for d4
c4 if white's king bishop moves anywhere useful
Behind the pawns is a lovely place to land knights (d3 via b4 is not uncommon, e3 via f5 seldom happens…)

Once white's pawns are fixed, one can wonder about what advancing them actually achieved : white loses as much time pushing pawns as black moving the knight.

¹ which I adopt as an all-time Alekhine Defense player myself.


What is the required Elo to beat a Grandmaster with queen odds? I heard someone saying today that he would beat Garry Kasparov if Garry played without a queen.

Were such handicap games ever played ?
Can a Grandmaster give queen odds and win against a 2000 ranked player?  Rook odds?

I have a hard time believing that there's a player on the planet who could beat me with Queen odds.  The strategy would be simple: trade off pieces pieces when possible.  I'm a USCF B player.

Here are some 'Queen Odds' games.  Play by the weak side is sometimes very dicey. Paul Morphy loses his game.  None of the games the GMs won went past 15 moves.  After that the Queen asserts too much power to overcome.

Here's a rant, lol.


Why does White fianchetto the light square Bishop in QID The line for Queen's Indian Defence goes like this -

[FEN ""]
1. d4 Nf6 2. c4 e6 3. Nf3 b6

Now, the most popular choice for white in this position is g3 preparing to fianchetto its light squared Bishop. After this, if Black wants to develop its light squared Bishop, the two choices are either Ba6(modern main line) or Bb7(old min line). Suppose Bb7 is played by Black. Now white can also fianchetto its Bishop and the play can go on. But here is my question - Given that Black plays b6, why does white go on with g3 ? Given that white's main light squares defender around the king (after white castles king side) is its Bishop on g2 which at some point in the game can be exchanged with Black's bishop on b7, isn't this line a bit more riskier?

However, this line has been played at top level a very large number of times. Like yesterday in Tata steel 2017 masters, Aronian played this opening and won a wonderful game. So what is the justification behind white's fianchettoing its light squared Bishop given Black has already done that?

There are 3 reasons why White fianchettos the light square bishop:

White's plan is to play e4 to gain space. The bishop on g2 supports this
Building from point 1), white could play e3, Bd3 then e4, but that is an extra tempo spent to play e4
White has latent pressure on the queen-side, and may be able to play discovery or pinning tactics with a bishop on g2


Is there a GUI software that exports chess diagrams for chess authors? Is there a program either Linux or a Windows program that can create a chess position and save it as an image. That image can then be used by the chess author in a book that is being written.

Chessbase products have to capability to export an image or using a chess diagram font as rtf to be pasted directly into word.


Chess software that shows current score When playing computer chess software I find myself wondering "who's winning right now according to the computer?". For example: I make a bad move but I don't realize it yet - but the computer looking 5 moves ahead immediately realizes that I've made a terrible mistake.

The computer AI must have this information internally (it's own evaluation of the current board position).  Is there an example of a computer chess game that shows this (ideally for iPhone so I can teach myself while on the train)?

Disclaimer: I wrote SmallFish.

I would recommend SmallFish on iOS. It's free, and it has the most powerful engine on iOS. It has very advanced analysis feature, look at the screenshot


Are there endgames which could be forced wins if not for the 50-move rule? Wikipedia's article on the fifty-move rule states:

All of the basic checkmates can be accomplished in well under 50 moves. However, in the 20th century it was discovered that some positions of certain endgames can only be won in more than fifty moves (without a capture or a pawn move). The rule was changed to include certain exceptions in which one hundred moves were allowed with particular material combinations. However, more and more exceptions were discovered and in 1992 FIDE abolished all such exceptions and reinstated the strict fifty-move rule.

I have never seen an example of this, though I used to think the K, N, B vs. K ending was one.  When is it possible to force a win in 50 moves or more, but not less than 50 moves?

Yes, there are quite a few endgames that require more than 50 moves with best play from the defender.

Wikipedia has a list of material imbalances where it could take more than 50 moves depending on the specific position.  Here are a few examples:

Rook and bishop vs lone rook (often a draw though)
Two bishops vs a lone knight
Two knights vs a lone pawn (the defender must have a pawn)
Four knights vs a lone queen (would never happen over the board…)
Queen and rook vs queen and rook
Two queens vs two queens


Carlsen - Ghaem, why does Black want to do e5? I am watching videos about the London system, and one example they use is this game.
[Title "Carlsen-Ghaem, Baku 2016"]
[FEN ""]

1. d4 d5 2. Nf3 Nf6 3. Bf4 e6 4. e3 Bd6 5. Bg3 c5 6. c3 Nc6 7. Nbd2 Bxg3 8. hxg3 Qd6 9. Bb5 Bd7

after 8. ... Qd6, the guy explaining the video says that Black is preparing to move e5, so White moves 9. Bb5 to avoid that. What is Black's plan with that move?

With ...e5, Black:

Opens a diagonal for the c8-bishop, and
Fights for central control.

Both of these adhere to chess principles, so planning for ...e5 is a very natural thing for Black.


Why is Alex Dunne's book 'How to Be a Class A Player' so valuable? I have been looking for this book for quite some time. I have his book, "How to Become a Candidate Master", but have had trouble finding this one at a reasonable price. Currently on Amazon, used copies are listed at $75 on up to over $100, with one copy listed at $655.04. Other sites have similar price ranges. I recently tried bidding on a copy on E-bay, but was outbid at the last minute where it sold for $31.00. Why is this particular book so hard to find at an affordable price, say $25-30?

Supply and Demand (Economics 101)

EDIT: Some additional clarification at the request of the OP.

Supply is pretty clear. It is fairly easy to measure although it can be a bit more tricky to get an accurate measure when it is very light.

Demand is a bit more nebulous. When there is enormous demand then it is also pretty clear. Where things become less clear is when demand becomes very light, when supply is also likely to be very light. Then you have actual, real demand and perceived or imagined demand.

Just as in chess between humans the clear logic of the situation can be distorted by emotion. It is not something you see in computer chess and you also see much less of it in big business. Suppose there is enormous demand for the latest Harry Potter book or Star Wars film. The companies controlling the product will try and match price and supply in a fairly mathematical way to maximize profit.

When supply and demand are very light then over emotional human beings make the decisions and things become a bit random.

Let me give some examples.

1) Cyril Northcote Parkinson, originator of Parkinson's Law, wrote an excellent book called "The Evolution of Political Thought". It has been out of print for decades. A few years ago somebody recommended it to me and I looked for it and found a cheap copy, < $5, from a bookseller via Amazon. Why was the price so much lower than for your chess book? Well, Parkinson was right wing and so not politically correct. A PC person trying to set a price is likely to automatically value it less in financial terms because they value it less politically. They will put a lower price on it, a more realistic price. And now I've checked on Amazon again and, lo and behold! a publisher called "Forgotten Books" brought out a new edition just 2 days ago so they must see or anticipate fresh demand.

2) In 1978 I found some old chess magazines scattered over a couple of shelves in a second hand bookshop priced at 10p each. As far as I could see they were all different issues of the same English magazine, "Chess". I approached the shopkeeper and asked for a price for the job lot. "£8" he said and I bought them. When I got them home and sorted them out I found I had the first 12 years complete from 1935 to 1946, importantly covering the war years when stuff like paper was in short supply. I've occasionally thought of selling them. But there are two questions I find difficult to answer. How much could I get? and How much would I want? You would think I should be able to get $1200, $100 per year. If a collector really wanted them he might pay me $12000, $1000 per year. But I certainly wouldn't sell for $1200 and nor for $12000. I would sell for $120,000 but I doubt there are any buyers at that price. I'm sure there is a lower figure, somewhere between $12,000 and $120,000 , which I would accept if offered but the offer is extremely unlikely. I could put them on the market for $50,000 but that would just be a more extreme version of your Alex Dunne chess book on offer for > $100.

You see where this is going? A big, professional business which bought the magazines for roughly $12 in 1978 would have no problem selling them for $1200 today. But I'm not a professional business. I'm a human being who is emotionally attached to these magazines. Supply is being distorted by emotion.

3) A large general store about 15 minutes walk from where I live has a charity table by the exit full of donated second hand books which you are encouraged to take in return for a suggested donation of 50p. A few months ago I came across the second part of John Masters' autobiography, The Road to Mandalay, which covers his progress during the second world war from lieutenant to colonel, and donated my 50p. I enjoyed it and so looked for parts 1 and 3 on Amazon. I found them, again for < $5. Despite John Masters' politics being middle of the road (he would be a Liberal Democrat in the UK today) and being the author of the book Bhowani Junction which was turned into a classic film, I suspect he is seen in modern eyes as old fashioned and not politically correct and this "value" is reflected in the low price asked.

I doubt very much if the actual demand for Alex Dunne's "How to be a Class A Player" is really so much higher than for my books by Parkinson and Masters but the emotional beings setting the price have no good way of accurately measuring it. Their judgement has been clouded. They are not behaving rationally and their stock will remain unsold ... unless you win the lottery :-)


Can one win with two dark square bishops and two light square bishops and his opponent has only one queen? Can one win with two dark square bishops and two light square bishops and his opponent has only one queen?

I remember seeing this endgame being analyzed in a video around 10 years ago (and I think the answer is yes) but could not find the video any more.

What you're referring to is a so-called "7-man" ending (2 kings, 1 queen and 4 bishops). Luckily for you, we have 7-man tablebases which are even available online and which allow us to analyze every possible legal 7-man chess ending.

[FEN "1q1k4/8/8/8/B7/1B6/1B6/2B1K3 w - - 0 1"]

Randomly setting up the above position shows that white is indeed winning, and generally most positions seem to show white winning. However, this isn't always the case, for example the following is a draw (white to move) because of the fact that black can either fork the king and one of the bishops, or can fork two bishops:

[FEN "3k3K/B3q3/8/8/8/8/B7/2B4B w - - 0 1"]

The tablebase also shows how the win often doesn't require that many ply, depending on the starting position of course.


(For training purposes) Are there any openings with rook pawns that are more effective than others (and if so, what are they)? (Originally I hoped a lengthy prologue would not be needed here, but some of the answers and comments have led me to write one so that the purpose of the question is clear, thus this is now much longer.)

When my child was around six or seven years old, I taught them the rules of the game and basic principles of opening play. At the time, chess didn't seem to hold a lot of interest. However, move forward a few years, and playing with school mates after classes were over led to an interest in the game. Quickly the kid rose above the novices at school and could even beat the teacher. Games between the two of us became competitive, even though I usually - but not always - win. The kid played a few tournaments: in the first 8 the kid had positive records in all but one, which was an open where all opponents were adults with ratings 300 to 500 points better with one exception - an unrated player. There are three trophies on a shelf from these tournaments, including first place from the beginners section of our state scholastic championship. Along the way, we signed up for a year of chess instruction from professional instructors. Also, the kid watches videos online about all aspects of the game and has worked through at least one well respected chess book. It is clear that the kid has a decent understanding of opening principles for someone at this level.

At tournament nine the kid had a bad day. One game in particular stands out: The opposing player opened with 1) a4 ... 2) h4 (or something similar, I don't have the scoresheet). Ultimately, the other kid won the game because my kid didn't know how to respond and got rattled. In some ways this isn't surprising, as any time any person encounters an unusual situation they can get confused and make poor choices.

Don't get me wrong, I certainly want my youngster to learn good chess principles. I don't want to play first moves like a4, h4, a5 or h5, in serious games, nor do I want the kid to do so (at all).  However, I've seen other games opened this way by players just learning the game (or using strange openings to confuse their opponents). In order to boost my kid's confidence and provide experience against games like this, I want to (occasionally) play openings at home that may be seen in games at this level. I don't expect to win these games, but that isn't the point: The point is to provide an experience that will benefit the psychological aspects of my kid's game if another player tries a similar opening in the future. Thus, I'm seeking some guidance on strange openings like 1) a4 or 1) h4, that I could at home play against my kid to help prepare for future tournaments.

Learning good chess principles and playing against clearly dubious openings like 1. a4 or 1. h4 are not mutually exclusive.  In fact, following solid opening principles is the best way to counter weak openings like this.

The moves 1. a4 and 1. h4 are both poor because they do not follow any of the opening principles.  Namely, they do not help control the center, they do not develop or prepare to develop any pieces and they actually reduce the king's options as to which side to castle on by weakening the pawn cover on one side of the board.

To counter such a move, you should simply play normal opening moves.  1... e5 or d5 is a good start.  If white allows it, you can take over the center by advancing the other central pawn two squares as well.  Then simply continue by developing the minor pieces and castling the king to safety.  At this point you will have a large lead in development if white has continued making many foolish pawn moves (which is likely against the type of players who open with 1. a4 or 1. h4) and should be able to make life miserable for the opponent.


In the immortal draw, why is the Queen sac 9...Qxa4+ considered the best move? After White's first nine moves in the Immortal Draw:

[FEN ""]

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

Why is 9...Qxa4+ the best move here?  Doesn't Black have an advantage with White's King on the third rank?  What hidden (from me, anyway) resource does White have that causes the Queen sacrifice to be necessary?

Where has it been mentioned that 9... Qxa4+ is the best move? but considering the alternatives it is the move that has made the game immortal, suppose black would have just followed up by playing positional chess only and managed to win, the game would have become just a case of positional example and hardly immortal. The rest of the game was not easy for white, number of times a playing a logical move would have lost white the game.


What should an arbiter do if a player has illegally stopped notating? Situation: a standard game, 1 hour 40 minutes for the game with 10 seconds increment per move. FIDE rules. White has two minutes left and has stopped writing down his moves, as he is allowed to because he has less than five minutes. Black has an hour left, but is blitzing along with white and has also stopped writing down the moves.

Unfortunately, I (the arbiter) was only made aware of this when the game was over (white resigned); I was there, watching the board and the clock, but couldn't see the player playing black because of other spectators and hadn't realized he wasn't writing.

If I had noticed during the game, I'm not sure what I should have done.

Is this something an arbiter can step in for by himself, or should I have waited for a complaint by white? (I think I could have just told black he should be writing down his moves)
More importantly, I think the only remedy in the rules is that the player has to repair his notation on his own time. This would probably have been impossible, and certainly nobody had written anything down. How could he do this? How could I check that he had done it, and not written down some random moves? Reconstructing on a second board would be so disastrous to white's concentration that it would not be in his favor.
Is there anything else I should have done, had I noticed during the game?

The first time you see a player doing this you should warn him and make him catch up on his time. If you are watching the game closely it is likely that there will only be 2 or 3 moves to make up.

Note that he need not write after every move but must not make a move if he has not written his previous move. In that case, particularly with a blitz finish you should immediately stop the clocks and only then issue the warning. If you feel that you have delayed significantly in stopping the clocks to the second player's detriment then you may adjust the second player's clock accordingly.

If he repeats the offence you should give him a final warning, make him catch up again and give his opponent an additional 2 minutes.

If he repeats the offence after your final warning then default him. Award him 0 and his opponent 1 unless it is impossible for his opponent to deliver mate by any sequence of legal moves. In that case (mate not possible) then award each player 0.5

Under the old rules stepping in without a complaint was at your discretion.
Under the new rules you are obliged to intervene regardless of whether or not there has been a complaint.

Edit: As Remco points out I have only answered the easy parts of his question above ;-). I've had a long think about the difficult part and this is what I came up with.

This situation is not covered explicitly in the rules. Instead, as the introduction to the rules state, you are left to make your own judgment based on analogous situations in the rules and by fairness, logic and special factors.

I will give two possible solutions which might help you if the situation arise again.

1) 8.1e states the following:

  If a player is unable to keep score, an assistant, who must be
  acceptable to the arbiter, may be provided by the player to write the
  moves. His clock shall be adjusted by the arbiter in an equitable way.
  This adjustment of the clock shall not apply to a player with a
  disability

When I have played in competitions where a player has been "unable to keep score" (the opponent of a teammate in a league match) the solution was that the player had 10 minutes deducted from his time before the start of the game. This was with a time control of 90 minutes for the game plus 30 second increment.

Using this as an analogous situation one possibility in the situation you describe would be to deduct 10 minutes (or such time as you deem appropriate) from the offender's remaining time. Of course this runs into the problem of what to do if the offender has less than 10 minutes left or even if he has only 11 or 12 minutes left. In those situations this may be an unjust solution.

2) Another possible solution would be to take the two players to a separate room (so as not to disturb the other players) after first stopping the clocks and noting the times and position on the board. There you could set up the position on one board and play through the game on another board up to the end of the recording of the moves. Set the offending player's clock going and invite him to try and reconstruct the missing moves. He is invited to do this until he has 5 minutes remaining at which point he is no longer required to record the moves. It may be that this added pressure will spur him on to succeed.

A variation of this solution would be to just reset his clock to 5 minutes and resume with neither player recording.

Whichever solution you decide on at the time I would advise you to have a copy of the rules with you and to explain your decisions with reference to the rules so that the players can understand your reasoning process. This should help reduce arguments and misunderstandings.


Lichess Puzzle 82753: Can white win with a queen and two pawns vs. rook and four pawns? Lichess puzzle 82753 involves a rook and pawn endgame where white sacrifices their rook to queen a pawn. The final position is the following (with black to move):

[FEN "2Q5/6p1/1K3pkp/8/8/4p3/r5PP/8 b - - 0 44"]

I'm not convinced white can win from here; it looks like black can swap off one pair of pawns, then set up a fortress. This seems to hold on against Lichess’s version of Stockfish, but I don't think it looks especially deep. Maybe there's a winning strategy for white, though, that it didn't find.

Question: Can white win with a queen and two pawns vs. rook and four pawns?

It looks very difficult for white to prevent the fortress.

The obvious sequence is something like -

[FEN "2Q5/6p1/1K3pkp/8/8/4p3/r5PP/8 b - - 0 1"]

1. ... Rb2+ (to kick the king one square further from the action) 2. Ka5 Rxg2 3. Qe8+ Kh7 4. Qe4+ Rg6 5. h4 h5 and black has 3 extra pawns, albeit the e3 pawn is likely to fall soon

If 5. Qf5 then 5... h5 anyway when 6. Qxh5 Rh6 leaves white struggling to save the h pawn.


Computers in correspondence chess In competitive correspondence chess, can humans win at all against computers? Do humans contribute at all to the game?

Provided that it is allowed by the rules, I fail to see how it is not just testing who has the best computer or the best computer program. In this scenario, the players would just be an interface, or not even that, since the computer can also send a move through the internet to the opponent.

I must disagree completely with the above answer. In the correspondence tournaments that I have participated in using a computer was considered cheating and if you were the tournament winner you had to do an analysis of one of your winning games, chosen by the tournament directors, to prove that you knew what you were talking about.

Second the computers main advantage against human players is their speed. A computer calculates thousand upon thousands of instructions per second and is able to analyse thousand of possible moves on each of its turns. However the computer has no true intelligence, which a human player does. The computer program Hydra was built to completely dominate the chess world and it did in fact beat every other chess program in the the world and has never been beaten by a human over-the-board. However it was beaten by a correspondence player in two games and drew their third game. I have been unable to find if the player consulted a computer or not, but as was pointed out in the discussions of the games on www.chessgames.com the player, correspondence chess International Grandmaster Arno Nickel, wasn't simply following another program since Hydra could beat all other programs as the time.

To say that unaided humans have no chance at all as though it were an obvious given is simply wrong. Take away the time constraints, have a motivated skilled correspondence player and there is a strong chance that the player will still win.

Hydra ran on a specially designed system that spread the processing required out over a network and is the only chess engine that would have a chance against the correspondence world champions if they were not constrained by time controls.


What is the strength of the Shredder Chrome app? Today, for the first time, I played against the Chrome app Shredder Chess, and at the "Hard" playing strength of the engine, I was easily able to beat it.

I am just about 1850-1900 Elo.  My question here is, what (Elo) strength does this engine play at? Can someone evaluate?

I would suggest players to play against it to check its strength.

This is a response from the maker of shredder. Hope it helps!

  We are using a different Shredder version on the Chrom App so this is
  very hard to tell in Elo, even for us.

Best regards
Stefan Meyer-Kahlen


What is the typical move prediction accuracy of human chess grandmasters? I couldn't find any data about the percentage of moves that a typical human grandmaster would be able to predict in games of other human grandmasters. To clarify my definition of accuracy: The predicting player would predict the next half-move for a position from a game he or she has never seen before, only being able to see past positions from the same game (preferably without even seeing the names of the players or when the game was played). To limit the influence of blunders, only games with classical time control should be used and the predicting player would have a limited time per move to make the prediction (let's say 1 minute per move). A correctly predicted move counts as 100%, an incorrectly predicted move as 0% and these numbers would be averaged over a large number of positions.

Since I couldn't find anything, I tried it myself and achieved 42 out of 119 (35.3%) in a randomly chosen grandmaster game (Alekhine vs. Erik Lundin, 1941, Round 7), but I'm quite amateurish, not a grandmaster. Randomly guessing legal moves would have achieved less than 5% in that specific game. My conditions do not have to be followed strictly, but I'm not really interested in accuracy results for blitz games, games of weaker players or "immediate", intuition-based predictions (i.e. without giving the predicting player time to think).

I'm interested in this because I want to know how accuracy varies with playing strength of the predicting player.

0.2785
It depends a lot on the opening as each would have different preferences and pet lines.
Middle games would be a bit better as there are fewer strategies to choose from for long term effort.
End games should be best as the simple positions are easier to predict moves although many end games could offer more variation to try for a win than middle games.
Overall the answer is 0.2785 based on a sample of one.  More samples should yield a more accurate statistic.
Although I doubt anyone really cares enough to do a study to see.