How many moves ahead does Anand calculate in his mind? I always wondered about this! How many moves ahead can strong players like Anand actually 'see' during the game? How does the calculation of a supercomputer like Deep Blue differ from that of strong human players?

first of all see here. here is a quote

  Asked how many moves ahead he can think, Kasparov replied that it
  depended on the positions of the pieces. "Normally, I would calculate
  three to five moves," he said. "You don't need more.... But I can go
  much deeper if it is required." For example, in a position involving
  forced moves, it's possible to look ahead as many as 12 or 14 moves,
  he noted.

for a supercomputer it obviously depends on how well-written it is, there is a concept called alpha-beta, which is used to limit thinking into unnecessary moves, like the computer usually wont consider the opponents (white) c3,b5,d6,f7, combo, on the first move. however after c3, b5 it should consider d6, and have a reply ready. from a page called Creating a chess engine from scratch on chess.com:

  A computer can easily evaluate a few million positions per second, a
  human probably 1-2 positions per second!! Usually speed is measured in
  MNodes/sekund which means million positions (Nodes in computer science
  jargon) per second. Fritz running on my old laptop does about 2.5
  MNodes while Deep Blue did about 200 MNodes per second. Raw power is
  not all - the evaluation function is also very important. Pretty much
  all engines use the same algorithm for searching through the search
  tree of possible moves to find the next move. This algorithm is known
  as alfa-beta search or it is some variant of this.

an important difference is that a computer has to consider things a human takes for granted, such as the concepts behind a known opening, even though a good program can remember which combos work (and rate them, then play based on  its ratings), its extremely difficult for it to recognize concepts, such as a fork independent of the result, this can be a advantage because a human may fork, and not see another better future move.

hope that helps!


How to measure strength of my own chess engine? I'm wondering how can I estimate ELO ranking of my own written engine. I figure out that I have to connect my engine with some well known engine (via UCI protocol?) to be able to play automatically many games. My first thought was to adjust ELO ranking of well known engine to finally have draw, eg. If I the result of 1000 games match between my program and other is about 500 - 500 then I'll know that my program has the same strength. The problem is that, as far as I know, we are not able to set any engine to play on particular ELO level. Do you have any other idea how to measure own engine ELO rating?

Implement UCI or Winboard protocol (just enough to play games).  Download some engines (e.g. via CCRL) stronger than your estimate and run a Gauntlet tournament in Arena/Winboard/Cutechess etc.  Hundreds of games at least.  Feed the resulting PGN output file into Ordo and it'll give you an ELO (for the time control you used).  Try different time controls etc if needed - depends on your target competitors.

https://chessprogramming.wikispaces.com/UCI

http://www.computerchess.org.uk/ccrl/4040/

http://www.playwitharena.com/

http://hgm.nubati.net/

https://github.com/cutechess/cutechess

https://sites.google.com/site/gaviotachessengine/ordo

For an initial quick ELO you could use Ferdinand Mosca's tool that makes an estimate based on your engine's performance with the Strategic Test Suite EPDs.

http://www.talkchess.com/forum/viewtopic.php?t=56653

https://chessprogramming.wikispaces.com/Strategic+Test+Suite


Is there a space between the move number and the move algebraic notation? I know everyone will say that this is a stupid question, but I'm going to ask it anyway...

Is there a space between the move number and the move algebraic notation?

In other words, which of these is the correct notation? :

1.e4 e5 or 1. e4 e5 ?

26.Nxe4 or 26. Nxe4 ?

8...Bb4+ or 8... Bb4+ ?

I've seen both with and without the space. On Wikipedia there are spaces. But I checked in three of my books and there isn't any space in any of them.

As you already noted, both are used. Either style is acceptable, and engines, pgn viewers etc. will usually not have any problems with either of them. The most common is probably without the spaces though, especially with long series of moves it can be argued it improves the readability a bit by not having unnecessary extra spaces. In books the notation will probably always be without spaces if for no other reason than to conserve page space over the length of the book.


What are "full piece" and "half piece" in chess? I'm reading Kasparov's Deep Thinking and I came across this sentence:

In one computer championship, a machine blundered a full piece early
in the game but its opponent declined to capture it.

When I googled it I also saw the term "half piece" but couldn't find any definition on any of them.
I'm not a native speaker and I'm not familiar with chess terms in English. I'm guessing full piece is an important piece such as queen or rook and half piece is a minor piece like bishop or knight but I want to be sure. Can you explain what they mean?

blundering a full piece

or

being a full piece down

are typical expressions in English chess literature.
With the little word "full", the author wants to make clear that the player has not only lost the piece, but that they also received no consolation material in return, i.e. one or two pawns. An alternative expression is "blundering a clean piece" / "being a clean piece down".
The typical scale is:

The opponent blundered/sacrificed a piece for two pawns.
The opponent blundered/sacrificed a piece for a pawn.
The opponent blundered/sacrificed a full/clean piece.

("Sacrifice" or "blunder" generally depend on the positional compensation for the loss of the piece.)
The "piece" in question may theoretically be a any of the "pieces" knight, bishop, rook or queen (pawns are not "pieces" and the king cannot be captured), but typically you would expect it to be either a knight or a bishop (in the other cases it would rather be e.g. "being a full rook down" or "being a full queen down").
The term "half piece" does not exist, at least to my knowledge.


Stockfish crashing on checkmate positions, and erroneous evaluation I asked the same question on Stockfish's forum.

Black to move in the classic scholar's mate position. mate in 1. Engine produce erroneous results?

position fen rnbqkbnr/pppp1ppp/8/4p3/6P1/5P2/PPPPP2P/RNBQKBNR b KQkq -

eval

Total Evaluation: -0.85 (white side)

Same position, except black checkmated white. White to move:

position fen rnb1kbnr/pppp1ppp/8/4p3/6Pq/5P2/PPPPP2P/RNBQKBNR w KQkq -

eval

Debug error! abort() has been called

Here is another position that crashes:

1b1B1k2/8/2B1p1p1/3n1p2/4KP2/6P1/8/8 w
eval

Go seems to work properly, showing that its mate in 1, and checkmate. However eval is not showing the correct numbers.

Or am I misunderstanding something here?

Everything works perfectly.

You should add 50 move counter to your FEN, but this is not the biggest issue.
The eval command returns a static evaluation of your position. It doesn't start the search, that's why Stockfish gave you back the results immediately.

Try this:

ucinewgame
position fen rnbqkbnr/pppp1ppp/8/4p3/6P1/5P2/PPPPP2P/RNBQKBNR b KQkq - 0 1
go movetime 1000

The engine gives you back mate in one:

info depth 126 seldepth 2 multipv 1 score mate 1 nodes 3781 nps 945250 tbhits 0 time 4 pv d8h4


Significant and efficient advice for amateurs I was once at a cafe on a Saturday; a novice joined our chess club meeting to have fun. After observing his opening moves, I concluded he randomly used pawns to attack the opponent (completely ignoring positioning, let alone developing, of pieces)

I offered to play a game with him. He told me about chess boxing (playing chess in between boxing rounds). After an enjoyable conversation, I then told him that chess IS like boxing: You must control the center, or be bullied around.

After enforcing this tip on him, I was extremely but delightfully surprised to find he was developing and positioning his pieces like a decent tournament player. The only issue was his tactics; he would regularly hang pieces and not realize in the middle game why he moved a piece. The main idea is the simple advice of going over the following list:

Asking what squares compromised the center (to which he answered correctly; e4, d4, e5, d5)
Asking whether pieces or pawns are stronger
Telling him every (opening) move must control one of those squares with the stronger resource

This list significantly improved his positioning, decision-making, and enjoyment for chess. My question is, what similarly short analogies have you told chess newcomers that connect real world situations with the nature of chess?

I don't like any of these answers as they are too wordy and assume a certain level of skill firsthand.

So, I would say:

1: Pay attention to what your opponent's move was. Many players get so focused on their own pieces they overlook what the opponent is doing, and suddenly they are dropping material. Chess is like a dance so pay attention to what your partner (opponent) is doing.

2: In association with #1, what does your opponent's move do? What are it's consequences? does it attack something? Does it leave something unprotected? Pay attention to that. Chess is like a conversation with a long-time friend. Let the move speak to you and give you all the information it has and don't interrupt the story it is telling you.

3: Do the basic "Captures, Checks, Threats" after every move. Just by looking at the board and mentally going over every capture, every check, and every clear threat, you will avoid losing material, and losing material is the single biggest problem for newbies. Chess is like boxing - you have to be able to read and anticipate what "punches" your opponent plans to throw at you. There are no surprises in chess - everything is before you. You only have to develop the skills to look closer to find what truths the position is telling you.


Move orders in the 6.Qc2 Anti-Meran Semi-Slav After 1.d4 d5 2.c4 c6 3.Nf3 Nf6 4.Nc3 e6 5.e3 Nbd7 6.Qc2 Bd6 White can play the so-called Shabalov-Shirov Gambit with 7.g4!? on the grounds that 7...Nxg4 allows 8.Rg1 and the important g7 Pawn is going to fall. Of course this is not a forced win by White, but this Gambit puts certainly some pressure on Black.

My main question is: why is Black always playing 5...Nbd7 and 6...Bd6 (or in reverse order) and not 5...Bd6 and 6...0-0, after which 7.g4 could be more safely accepted  with 7...Nxg4 (the g7 Pawn is no longer en prise after 8.Rg1)? Is there any particular reason for playing 5...Nbd7 or 6...Nbd7 before castling?

A lot of opening play is about what you are trying to avoid. While sharp, black does quite well against 7.g4. In reality, the quieter lines seem to have much more venom if the figures in Mega 2020 are to believed.

In addition, with the move order you mention, white can get e4 in very early, or can play the Karpov line among other choices. The main line I am giving scores at 73.4% compared to only 56.2% for Shirov's g4. I think that g4 was a great surprise weapon, but now, it has been analyzed sufficiently with computers, and it no longer the great threat it once was. Black can respond with the best move, h6 instead of taking on g4.

 [FEN ""]

 1. d4 d5 2. c4 c6 3. Nf3 Nf6 4. Nc3 e6 5. e3 Bd6 (5... Nbd7 6. Qc2 Bd6 7. g4 {The Shirov Gambit.} h6!) 6. Bd3 (6. Qc2 O-O 7. Be2 Nbd7 8. O-O {Karpov's favorite line.}) 6... O-O 7. e4 dxe4 8. Nxe4 Nxe4 9. Bxe4 Nd7 10. O-O Nf6 11. Bc2


Is it possible to play the Najdorf Defense if white played 1. d4? After white plays 1. d4, is it still possible for black to play the Najdorf Defense?

Is it possible, for Black to play in a way in order to reach a Najdorf setup? If so, how should Black continue?

If White starts with 1.d4 it is possible to reach a Najdorf position, for example:

[FEN ""]
1.d4 d6 2.e4 c5 3.Nf3 cxd4 4. Nxd4 Nf6 5. Nc3 a6

However, White has other moves on move 2, which still give them an advantage: 2. c4 and 2.Nf3, also White could play 3. c3. So Najdorf is not that easy to get. Moreover, some people play 1.d4 to avoid Sicilian and especially Najdorf; they will certainly not follow the above line.


Bishop's Opening, Berlin Defense, white goes Qf3; how to exploit with Black? So:

[FEN ""]
1. e4 e5 2. Bc4 Nf6 3. Qf3

Qf3 should be a mistake for white, but I just can't get a decent position whenever I play this with Black. If I go on to castle kingside the queen and bishops are already well placed to attack; if I try to develop on the queenside white just pushes the g and h pawns and my knight runs out of squares very quickly.
Excuse the noobness, I'm obviously a beginner.
So.. how to continue?

This opening is not dangerous.

You have no weaknesses.

White's Queen is doing nothing useful while blocking the best square for White's King's Knight.

Once you develop your Queen's Knight to c6 White has to worry about Nc6-d4 with a big gain of time.

Your f6 is fine – your knight masks it for now, and once you castle kingside it's well-defended and easily reinforced, while White will have trouble bringing up anything else to attack it.

Castling queenside is probably not indicated, although the White pawn-storm you mentioned is both premature and far too slow.

It's not like you're winning here, but White is not going to wrest any advantage out of this position without being given a gift. Whatever problems you're running into are not due to this opening.


How do I seriously analyze my tournament games and become stronger doing so? I'm a Class B, but I would like to reach Master Class one day. I been playing a lot of OTB games recently, and I would like to spend time studying my weaknesses. My coach noted some major weaknesses of my play. Unfortunately, I currently can't afford any more chess lessons or tournaments, for a two month period. I would like to uncover more weaknesses on my play and become significantly stronger. How do I seriously analyze my games?

If it helps, my chess engine is Fritz 15. I'm not sure how do use the engine. Any advice on that would be greatly appreciated.

I think engines only help for tactical improvements, not strategical. I saw a lot of moments where engine suggestions was far from perfect, strategically.

Also, in endgames, you can't depend on engines even tactically.

I used to use Fritz GUI with strongest engine(for that day) for blunder checks and tactical misses, in Fritz GUI you can do it easily with one click, give the game, leave the computer for 30 mins and when you return you get an tactically annotated game. With this, you can improve your tactics ability.

But remember, use engine suggestions only for finding answers for tactics, if you can't understand why the answer is correct, then you can't benefit of using engine.

For strategy, best way is to find someone who is at least 300 elo higher than you, and analyze games together. Also read every strategy classic, if you didn't read yet.

And for endgames, you need to be a real geek in reading endgame books. Best way is to read quality endgame books, and try to solve endgame studies.

Studying endgame is really beneficial for elo improvement, because people under 2000 elo don't care much about endgame. If you get a good endgame knowledge, then you can go for exchanges happily and solve your problems in endgame. Also, it's said that a good endgame knowledge requires an excellent grasp of pieces and their abilities, which also naturally boost your tactical ability.

My favorite endgame book: http://www.amazon.com/Secrets-Pawn-Endings-Karsten-Muller/dp/1904600883 which is an excellent and complete source for pawns.

Lastly, about openings, don't memorize, but understand. Don't memorize and use popular strong lines just because they are popular and strong, if you don't understand the harmony in the moves, then the opening won't be strong in your hands.

When you use an opening which you understand the strategy within, deeply, you almost always arrive a better middlegame/endgame comparing your opponent, which makes you win the game.

I won a lot of matches against strong players with openings which are quite unpopular, but I understand very well. And I saw these strong players fail to find correct continuations :)

To give an example, I used to play Dutch Defense with blacks successfully, later I wanted to play it with whites, which found silly by others from time to time. But because I knew Dutch very well, it went good with whites too, and I got quite good results.

A bit long but, these are my advices. Hope it helps.


Agreeing a draw after checkmate In a club game this week, checkmate was reached legally on the board, however the players thought it was stalemate, shook hands and signed the scoresheet as a draw.

The "winner" was a young junior, she initially wrote 0-1 on the scoresheet but then the "loser" pointed out that he thought it was stalemate, and so the junior accepted this and changed the score and signed it.

Being a club game the arbiter let the result stand; but if this happened in a FIDE-sanctioned tournament then what should happen?

According to the FIDE Laws of Chess

5.1        The game is won by the player who has checkmated his opponent’s king. This immediately ends the game, provided that the move producing the checkmate position was in accordance with Article 3 and Articles 4.2 – 4.7.
8.7    At the conclusion of the game both players shall sign both scoresheets, indicating the result of the game. Even if incorrect, this result shall stand, unless the arbiter decides otherwise.

The "winner" won the game. However, both players signed both scoresheets indicating 0.5 - 0.5, so that would be the result unless the arbiter were involved.

In this case, I think the arbiter made a mistake. The young junior should have stuck to her guns and kept the 0-1. She agreed to mark it a draw because she didn't understand that she won regardless of her opponent realizing he was beaten. Were she an experienced chess player, I would absolutely let the 0.5 - 0.5 stand, but I think you need to help young players understand the rules without penalizing them for trying to avoid conflict. I think the gender dynamic and potential age dynamic (you explicitly mentioned she was young, but made no mention of his age) should also be considered in the decision.


How to save/open games on Stockfish for Mac I just downloaded Stockfish, input a couple games, and saved them. They look like generic documents when I save and try to open. I just used the default Save function in Stockfish. Finder tells me they are .pgn documents. The problem is when I try to open I get this message:

The document “example” could not be opened. Stockfish cannot open files of this type.

So what are the steps to save a game so that it can be opened later?
(This question is so basic that I couldn't find any forum help on it so I guess I'm the only one dumb enough.)

I don't own a Mac, so I can't test these myself (and the solutions' efficacy might vary with software/firmware), but here are some solutions that have worked for others:

Per ref. 1:

Note: Invalid moves in the PGN file seem to prevent the file's opening.
At the end of every line in the PGN file, add a space. Then they should open with the current version of Stockfish for Mac.
Open the PGN files with a text editor and convert the line endings to CRLF (Windows line endings). Then they should open with the current version of Stockfish for Mac.
Compile and run the latest Stockfish for Mac development version from GitHub. This has the fix.

Per ref. 2:

If you're playing a chess variant, then add a FEN tag to the PGN file (if there isn't one there already).

FEN tag example:

  OTHER TAGS GO HERE
  [FEN "brkbqnrn/pppppppp/8/8/8/8/PPPPPPPP/BRKBQNRN w KQkq"]
  [SetUp "1"]

  MOVES GO HERE

References:

http://support.stockfishchess.org/discussions/problems/3362-pgn-files-not-opening-stockfish-for-mac
https://www.reddit.com/r/chess/comments/2w9zgf/how_do_i_use_stockfish_with_chess960/


How many times should I let my opponent know they forgot to press their clock? I've had this question on my mind for a while, and I searched around and found a previous question (Should you let your opponent know if they have forgotten to press their clock?) that touched on the subject.  In that previous question, it was asked if one should remind one's opponent if they forget to press their clock.  The general consensus in the answers seemed to be, yes, remind them - and I always have done so, myself.  My question, though, is - at what point do you stop?  I've played against a number of opponents who've had the habit of forgetting to press the clock after almost every move.  After reminding them the third or fourth time, it starts to get annoying, and it distracts from my own concentration on the game if I have to continually watch to make sure my opponent deals with their clock as they're supposed to.  At what point does one just give up, and sit there and let their clock run until they figure it out?  At what point is it no longer poor sportsmanship to refrain from warning them?  If I've already reminded someone four times in one game to press their clock, does it make me a bad sport if I just sit there without speaking (or gesturing towards the clock, which is what I normally do) and without making a move, and let their clock run out when they do it the fifth time?

And actually, now that I'm thinking about it - am I actually committing a rules infraction myself, by communicating with my opponent so frequently about their clock?  I've always wondered about that, too.

Its a matter of opinion, and much more likely to occur at the beginner or amateur levels of chess.

I believe it is best to show the high levels of sportsmanship and notify them immediately for the first couple of times they forget to press there clock.
If they continue to forget to press the clock, start by waiting 1 minute, followed by 2 and 3 etc. … If it's becoming a serious problem and your position (clock and board) is sufficient, I would consider going for a walk to look at other games in attempt to drill the point home.

Drilling deeper into the matter, when players don't press their clock, they are costing yourself and themselves XX seconds from increments and can cause problems when playing games with multi time control periods.


Good master games for learning how to win from a superior position I have recently managed to build up my opening repertoire to something that will no longer cause me to fall into lost positions against decent players, so I can no longer blame my losses upon bad opening preparation.

I still need to improve in order to get to a level that I'm content with, and after doing some soul-searching, I am convinced that I still have one glaring weakness in my games that needs some serious work: I am bad at converting a positional advantage into a win!

I haven't learned how to think efficiently, and what to look for when I'm given a good position. I still think way too much in terms of concrete variations, and I have a hard time forming coherent long-term plans to improve my positions.

Therefore I am planning to start studying classical games from past masters, where they convert an edge into a clearly winning position with confidence and clarity. The masters I have in mind are first-and-foremost:

Rubinstein
Lasker
Capablanca
Botvinnik

Others, like Karpov or Kramnik (or any other great technical player, for that matter), are also interesting.

But there is one big problem: These players have all won a huge number of games, and obviously it will not be possible for me to go through them all.
I want to study their good technical victories, not some random game that they won based on obvious blunders from their opponents, or where they just won by launching an early attack and crashing through before the opponent knew what happened.

What I'm looking for is a list of famous games to study from the players mentioned above, so I have somewhere to start.

Rather than recommend a series of games, I am going to recommend the book Excelling at Technical Chess: Learn to Identify and Exploit Small Advantages by Jacob Aagaard.

Here is the blurb (emphasis is mine):

  In this book Jacob Aagaard studies the valuable skill of chess technique. He arms the reader with several endgame weapons that every strong technical player has in his toolbox. These include important skills such as schematic thinking, domination, preventing counterplay, building fortresses and utilizing zugzwang. These tools are illustrated in deeply analyzed games containing numerous different themes. A serious study of this book will ensure that the reader no longer need fear the word "technique"!


Grunfeld Defense as White This opening gives White a big center and aims to destroy it. I have trouble playing the exchange variation as White because Black has great piece activity while my pieces are stuck in passive positions. Is there another variation which also allows White to get a big center while minimising problems?

I think Bronstein had the right idea in the Exchange Grunfeld against Boleslavsky in the 1st game of the 1950 candidates final. It costs a little material, but it's White who got the active pieces, while the center expanded.
[FEN "rnbqkbnr/pppppppp/8/8/8/8/PPPPPPPP/RNBQKBNR w KQkq - 0 1"]
[Event "Bronstein - Boleslavsky Candidates Playoff"]
[Site "Moscow URS"]
[Date "1950.07.31"]
[EventDate "1950.07.31"]
[Round "1"]
[Result "1-0"]
[White "David Bronstein"]
[Black "Isaac Boleslavsky"]
[ECO "D87"]
[WhiteElo "?"]
[BlackElo "?"]
[PlyCount "63"]

1. d4 Nf6 2. c4 g6 3. Nc3 d5 4. cxd5 Nxd5 5. e4 Nxc3 6. bxc3
c5 7. Bc4 Bg7 8. Ne2 O-O 9. O-O cxd4 10. cxd4 Nc6 11. Be3 Bg4
12. f3 Na5 13. Bd3 Be6 14. d5 Bxa1 15. Qxa1 f6 16. Bh6 Qb6+
17. Kh1 Rfd8 18. Rb1 Qc5 19. Bd2 b6 20. Bb4 Qc7 21. Rc1 Qb7
22. Qb1 Rab8 23. dxe6 Nc6 24. Bc3 Ne5 25. Bb5 Rbc8 26. Bxe5
Rxc1+ 27. Qxc1 fxe5 28. Bd7 Qa6 29. Ng3 Qxa2 30. h4 Rf8
31. Qg5 Rf6 32. Qxf6 1-0


Feedback on my game? [FEN ""]
[Title "Bskg vs NN"]
[Result "1-0"]

1.d4 d5 2.c4 dxc4 3.e3 Nc6 { A mistake, blocks counterplay based on c7-c5 } 4.Bxc4 { Seems passive and the light squared bishop is locked in. However, e7-e5 is difficult with the knight on c6 in view of d4-d5 } 4...e6 5.Nf3 Bd6 6.Nc3 Nf6 7.O-O O-O 8.e4 { Is this move good? It was the only plan I found } 8...e5 9.dxe5 { I thought I would have an advantage in the following endgame due to my central pawn, but I now like d5 better as it seems more ambitious } 9...Nxe5 10.Nxe5 Bxe5 11.Qxd8 Rxd8 12.Bg5 { I think the simplification was a bad idea for white, black's d-rook and dark square bishop are very strong. } 12...b6 13.Bd5 Rb8 14.Rfd1 { Trying to take the initiative with tactical threats and taking the open file } 14...Rf8 15.h3 h6 { Isn't Ba6 better? } 16.Be3 Bb7 { nxd5 was a bit scary and Ba6 would be good, but after the move that was played I think white is better again. The rook is bad on b7 and white gains time } 17.Bxb7 Rxb7 18.Bd4 { bxd4 activates white's rooks and Re8 is strongly met by f4 } 18...Re8 19.Bxe5 Rxe5 20.f4 Rc5 21.e5 { The knight must move to a terrible square } 21...Nh5 { Here the knight will be lost } 22.Rd4 Rb8 23.g4 Nxf4 24.Rxf4 Rxe5 25.Rd1 c6 26.Rd7 a5 27.Rfxf7 Rg5 28.Ne4 Rg6 29.Kg2 h5 30.Kf3 hxg4 31.hxg4 Kh7 32.Ng3 Rg8 33.Nf5 Kh8 34.Ne7
1-0

I had white.

A good game between equally matched players.

3. e4 is more common and is one of the points of the gambit - you gain more space. You're going to use an extra move to get it to e4 on move 8. Might as well do it on move 3.

9. dxe5 allows a series of trades that sucks the life out of the game. I think 9. d5 is slightly stronger and is what I expected you to play.

14...Rf8 made my face hurt. Instead, consider Ba6 or Be6. The latter allows an isolated e pawn but it connects the rooks and removes White's best piece.

15...h6 I'd have Nxd5 to kill that good Bishop. That would be add sense to the Rf8 move.

After 16. Bb7, followed by ... c5, Black's Rook is not so badly placed and is closer to making a battery.

21... Nh5 A Knight on the rim is dim.

26. Rd7 is a strong move. Note this would not have been possible had Black not wasted a move with 22... Rb8 but instead simply pushed the c pawn per a previous comment.  That is, consider 18... Bxd4 19. Rd4 c5 20. Rd2 Re8.  White may be better, but there's no obvious win here.

The game didn't do a lot for me as the trades removed most of the tension. Had Black not blundered the Knight it was looking drawish though I did prefer White's more active Rooks.


How has chess managed to remain a competitive sport despite engine dominance? As much as people fear losing their jobs to machines that can do them better, Chess has seen the exact opposite take shape. There have been extremely strong chess bots since Kasparov's time, and more recently, the supremacy of chess engines has only been reinforced by neural network engines like AlphaZero.
Yet, people seem to have just accepted the fact that the skill gap between engines and human players is insurmountably vast, and chess has, in the face of human obsolescence, continued to grow even more popular. More people play the game, and more importantly, people continue to compete. Moreover, prize pools have only gone up as chess becomes an attractive eSport with some matches easily attracting tens of thousands of viewers.
My question is: how? How has human competition endured when even the best players perform at a level that's barely child's play for any run-of-the-mill engine? Now that we have "accepted" that we are worse, why do we still want to see who's better?
Chess isn't the only example of this happening either - spelling bees, certain eSports, and even weightlifting competitions are all fields where machines can do the task better, faster, and more reliably. What does this pattern tells us about how human society as a whole will adapt to increasingly powerful machines as they arrive?

For the same reason the Tour de France is still a thing even if you could perform much better on a motorbike. Most chess enthusiasts didn't stop playing chess after noticing there's some other person whose rating is 1000 points higher than theirs, and won't stop because there's a machine 1000 stronger than that person.
A good amount of chess players don't care at all about computer chess and will only use engines as an assistence to analysis.


What kind of hand-crafted features do top performing family of engines use to evaluate a position? AlphaZero paper which introduced the engine which allegidly outperformed stockfish mentioned the following:

  These programs evaluate positions using features handcrafted by human
  grandmasters and carefully tuned weights, combined with a
  high-performance alpha-beta search that expands a vast search tree
  using a large number of clever heuristics and domain-specific
  adaptations.

In particular I am interested in a claim about features handcrafted by human
grandmasters. The paper didn't provide any examples, neither it references anything here. To make the question less ambiguous, let's narrow the scope of programs to just a couple of best performing families of engines (stockfish, sugar, komodo, houdini)

So my question is: what kind of hand-crafted features do top performing family of engines use to evaluate a position?

The paper is right. Traditional chess engines use a set of tedious hand-crafted features for positional evaluation.

I'd say nothing surprising, to name a fews (I can't name everything):

Mobility bonus
Outpost bonus
Attack bonus
Rook on the seventh rank
Material advantage
Minor pieces behind pawn

  https://github.com/official-stockfish/Stockfish/blob/master/src/evaluate.cpp

If you take a look at the source code, it's quite complicated. Difficult programming for something that is understood even by chess beginners.

What about replacing the entire file with a deep neural network? Training a network is easier than tweaking those numbers in the file.


Is my solution to this puzzle wrong or a transposition of the official one? I saw the following puzzle recently in a newspaper:

  Black to play and win

6rk/6qp/2Bp4/P1pP1p2/3bnP2/6BQ/7P/5R1K w - - 0 1

My proposed solution was

1. ...   Nf2+

and the lines I foresaw were

2. Bxf2  Bxf2
3. Rxf2  Qg1 mate

2. Bxf2  Bxf2
3. (something else)  Qg1+
4. Rxg1  Rxg1 mate

2. Rxf2  Bxf2
3. Bxf2  Qa1+ and interposing B or Q only delays the end

However, the given solution was

   1. ...   Bf2!
2. Rxf2  ...
 (If 2. Bxf2?  Nxf2+  3. Rxf2   Qg1 mate)
 2. ...   Nxf2+
3. Bxf2  Qa1+ and white resigns

I can see three possibilities:

I missed something
My solution is as good as the official one
They're actually equivalent under transposition

Which is the case?

They're not equivalent, but your solution is just as good. In fact, it's more easy to find because Nf2+ is a 'forcing' move.


What happens if a player suffers a time penalty but doesn't have enough time left? Wikipedia's article on threefold repetitions gives a story about an incorrect threefold claim by Karpov against Miles:

  The clause about the right to capture en passant and the right to castle is a subtle but important one. In a game between grandmasters Anatoly Karpov and Tony Miles (Tilburg 1986), Karpov had less than five minutes remaining on his clock in which to finish a specified number of moves or forfeit the game. He claimed a draw by repetition after checking his scoresheet carefully, whereupon it was pointed out to him that in the first occurrence of position, Black's king had had the right to castle, whereas in the second and third it had not. Tournament rules stipulated that a player be penalized with three minutes of their time for incorrect claims, which left Karpov's flag on the verge of falling. By then, Miles had taken the draw ...

What if, instead of five minutes left, Karpov only had two minutes? Does he instantly lose on making the incorrect claim?

According to the FIDE Laws of Chess:

  12.9 Options available to the arbiter concerning penalties:

  12.9.1 warning,

  12.9.2 increasing the remaining time of the opponent,

  12.9.3 reducing the remaining time of the offending player,

  12.9.4 increasing the points scored in the game by the opponent to the maximum available for that game,

  12.9.5 reducing the points scored in the game by the offending person,

  12.9.6 declaring the game to be lost by the offending player (the arbiter shall also decide the opponent’s score),

  12.9.7 a fine announced in advance,

  12.9.8 exclusion from one or more rounds,

  12.9.9 expulsion from the competition.

In such situations, for a first offence, the arbiter would always add time for the opponent. He would never reduce the time for the player. Only if it were a third or later infraction of the same rule and the player had been warned would more serious action be taken like defaulting the player.

There is a general principle in the arbiting world, which is seen in the move away from allowing quickplay finishes, that the actions or decisions of the arbiter should not decide the game. Reducing the player's time to less than zero would do just that and would never be done.


Best reply to C46 Four knights, Italian variation I am a low rating player and I would like to understand why 5 Nxe4 is consider to be the best replay by white on the C46 Four knights, Italian variation opening against 4 Nxe4 by black. Instead of 5. Bxf7+.

This:

[FEN ""]
1. e4 e5 2. Nf3 Nc6 3. Nc3 Nf6 4. Bc4 Nxe4 5. Nxe4

Instead of this:

[FEN ""]
1. e4 e5 2. Nf3 Nc6 3. Nc3 Nf6 4. Bc4 Nxe4 5. Bxf7+

5.Bxf7+ has a reasonable idea behind it, in that it exposes Black's king and jettisons White's bishop before Black can use the fork trick on it that would follow with 5.Nxe4 d5. However, it has some concrete problems:

After 5...Kxf7 6.Nxe4, Black plays 6...d5 and forms a massive center.
Black's king turns out to not be vulnerable on f7. It will quickly retreat to g8 where it is relatively safe.
White's knights are going to get kicked around a lot with loss of tempo. If he plays 7.Neg5+ Kg8, both ...h6 and ...e4 will attack knights that don't have very good places to flee to.

In contrast, after 5.Nxe4 d5, Black regains his sacrificed piece, but has to break up his pawn center in the process. After 6.Bd3 dxe4 7.Bxe4, White no longer has his opening advantage but the position is relatively equal.

The lesson from all of this is that 4.Bc4 is not a very good move. The standard alternatives are 4.Bb5 (Spanish Four Knights), 4.d4 (Scotch Four Knights), and 4.g3 (Glek Four Knights), which all keep White's opening advantage.

P.S. I should point out that there is a third alternative for White's fifth move, 5.0-0, gambiting a pawn for a lead in development. This is likely actually better than either 5.Bxf7+ or 5.Nxe4, but if you want to play a gambit like that then there are much better ones to play than the Italian Four Knights.


How are the "Classes" - A, B, or C, players defined? On this website, the following ratings are given:

  1200-1399 = 'D' player - usually a beginner
  1400-1599 = 'C' player - average club or tournament player, most people can achieve this level if they work at it
  1600-1799 = 'B' player - consistently above average
  1800-1999 = 'A' player - strong club player, takes the game far too seriously!, has lots of opening knowledge
  2000-2199 = 'Expert' - extremely strong, consistent player with the possibility of achieving Master rating, may have real talent.
  2200-2399 = 'Master' - strongest amateur rank, hasn't quite got the hang of things yet but maybe on day he/she will wake up.

  International professional players have two ranks:

  2400-2499 = 'International Master' - weakest professional rank; strong, experienced international player, eats Masters for breakfast
  2500+ = 'Grandmaster' - eats IMs for breakfast, lunch and dinner, a star in the firmament of Caissa, a chess genius who thinks nothing of playing 20 and 30 board simuls against Experts and Masters and is disappointed if he/she doesn't win every game, capable of playing 10-20 blindfold games at the same time, and winning, etc. etc, in short, an all around bricks and mortar, brass bound b*st*rd of a player, but they do lose on occasion, sometimes to players with a much lower rating and computers are better than that these days.

Note that these ratings are for "USCF". When I see these kinds of "levels" of player on this site, is this the common and correct definition of what they refer too? If not, what is the correct definition?

The definitions you post are more of less correct though some levity has been inserted. The descriptions for the under-2400 ratings are consistent with the USCF.

IM and GM titles are not awarded by the USCF. They are awarded by FIDE and are based not upon rating but on achieving certain results at recognized tournaments.  That is, if one scores well enough at a FIDE tournament (based upon the competition), one earns an IM or GM "norm".  When one earns three norms, one is awarded the title.


What happens in this multiboard scenario? You are playing 4 players at the same, you are black, white, black, white.

Player 1 makes his move, you switch to player 2 and make the same move as player 1, and so on, with player 3's first move becoming your move to player 4.

you then go back to player 1 and respond with player 2's response to your move.

if you sense a mistake, you 'go for gold' and 'play your hunch'.

does this have a name?

That's a trick once performed by Derren Brown.

This article calls it "mirroring technique" and claims it is more than 25 years old, but I don't think this is a very well known term.  If you are interested in more information about this trick you should probably google "Derren Brown Chess".


Training tactics - doing more easy puzzles or fewer, but deep, puzzles? I know daily tactics training is very beneficial.  However, what is the best way to do so?

Lets say I have 15 minutes a day.  Is it better I do 3/4 puzzles in detail, spend 5 minutes on each analysing each move in and ensuring I get the puzzle correct or is it better to do 20-30 puzzles, each one based off only a few seconds of thought (however at the same time seeing many more positions)?

Also, is it better to see many new tactics, like chess tempo, or to get a book and do the same 100 puzzles until you get them all right?

I would say it really depends on your skill level. If, like me, you're a relatively weak player, playing lots of "easy" and "medium" puzzles is probably more beneficial. You want to train yourself to recognize patterns and interactions that are likely to come up in a game. In that case, seeing lots of different tactics is probably best.

As you get stronger, the basic tactics from "easy" and "medium" puzzles will be almost always seen by both players (you still need to recognize them because if you miss your opponents simple fork, you're going to have a bad time). Focusing on harder puzzles will help you find those more complex patterns and tactics in your games. In this case, both lots of tactics and complete understanding of every puzzle is probably the desired outcome.

I've listened to GMs talk about puzzles where they look at it for hours and when they have a "solution" they still don't actually know if it's solved until they consult an engine, the puzzle creator, or their coach. (Compared to a simple forced mate in X puzzle).

Additionally, it's all about where your strengths and weaknesses are. If you're really good at a particular type of tactic, de-prioritize continued training of that tactic and focus instead on your weaknesses.

Most people have a bias where they would rather do 5 puzzles they're good at and 1 they're bad at, which is fine if you're doing it purely for entertainment, but if you're trying to improve, reverse the ratio.


Queenless Imbalanced Middlegame I was analyzing the following position for one of the correspondence games that I am playing. In the position, white is up 2 pawns and with my limited understanding, I can't see any real compensation for black. I checked with Stockfish 10 at depth 29 and it evaluated the position as +0.63. I also checked with Komodo 13.2 which gives the position as +0.50 at depth 25. My question is basically on what is the compensation that black has for the 2 extra pawns or is there, in reality, no compensation and I didn't let the computer go into a higher depth.

Here is the position(Black to move):

[fen "r1br2k1/pp3pbp/6p1/4P3/5P1P/2N1P3/PP4P1/R1B1KR2 w - - 0 1"]

First, I don't think that there is any doubt that black has significant compensation, but clearly, black is still trying to hold this, not win it when talking two computers playing each other. I believe that between two humans, I would probably prefer black.

If you have an eval that says +.63 for white, but black is down two pawns, you have to realize that it means that black has roughly 1.37 in positional compensation.

White obviously has the two pawns, but black has the two bishops in a relatively open position, is ahead in development with the Rd8 already controlling the file, and h4 is a target that at the very least can be used to gain a tempo. Lastly, the g4 square is a wonderful spot for the Bc8, and helps control the open file. Also, the Rf1 is poorly placed, and the Bc1 currently does not have a bright future. One of the extra pawns, although I am going to trade it off, is currently doubled.

I analyzed this using a computer, and it is a VERY difficult position to get a handle on because so many of the moves are almost equal in the evaluations. In each case, what I did was let it get to a depth of 33-37 using Stockfish 11, and then I would advance the game by a move and force in the best move, and then let it get to a depth of 33-37 again, and so on. So, by the time I got to the 16th move of the variation, it was still looking 35+ ply ahead.

Here is the variation I found, and I have notes as to why the moves are being played. At the end, it is still only +.41, and despite the two pawns minus, it is hard to believe that white can win due to black's incredible activity, and the Kg8 will enter the game soon.

 [FEN "r1br2k1/pp3pbp/6p1/4P3/5P1P/2N1P3/PP4P1/R1B1KR2 b Q - 0 1"]

 1... f6 2. e4 Bg4 3. e6 (3. exf6 Bxf6 4. g3 Bxc3+ 5. bxc3 Rd3 6. Kf2 Re8 7. e5 Rc8 {and black is almost winning...f5 is already the only move so white can play Bf4 next defending g3.}) Bxe6 4. Kf2 Rd3 (4... Bg4 5. Be3 Rd3 6. Rfe1) 5. Rd1 (5. Be3 Bg4 6. Rac1 Re8) 5... Rxd1 6. Nxd1 Rc8 7. Nc3 f5 8. e5 Bf8 {Ba3 threat.} 9. Bd2 a5 {Idea a4-a3.} 10. Ke1 {To prophylactically protect the Bd2 after a4; Na4 Rc2} Bc5 11. Rd1 Be7 $1 {Only after a2 is undefended does this combined with a4 work.} 12. g3 a4 $1 13. Nxa4 (13. a3 Bb3) 13... Rc2 14. Rc1 Rxc1+ 15. Bxc1 Bxa2 16. Nc3 Bc4 $14 {Nd1 +.41.}


What is an accurate way to evaluate chess positions? I've been interested for a while about a computer chess AI algorithms (and got the chance to work on one at some point) like Minimax, and as the core component of these algorithms is the so-called evaluation function to determine what is a good board configuration, and what is a bad one.

In other terms, given a configuration of your Chess board, how do you determine that it is to your advantage, and with what degree of confidence?

For example:

If you own the center, this is rather favorable.
If you have more pieces than your opponent, this is rather favorable.
If you lost your Queen, this is rather not favorable.
If you have a pawn that is close to being promoted this is favorable.
...

So I would like to ask for some advice on how to create a good evaluation function, based on some expert knowledge about the Chess game in general. And if possible, a degree of favorability (say between 1 being very not favorable, to 100 being extremely favorable).

The idea in the end is to be able to create an algorithm that will look in the tree of possibilities up to a certain depth and evaluate what the most favorable configuration for next move is (taking into account several moves in the future) based on what is favorable to the player and not favorable to the opponent. But without a good evaluation function the algorithm is nothing.

Here's a good starting point. Material comparison is key (and easy), then you can tune that to consider positional aspects like open ranks/files/diagonals, pawn structure, etc.

https://www.chessprogramming.org/Evaluation


Can one theoretically prove that these moves are marginally better? I heard that for the first move, 1. e4, 1. d4, 1. c4 and 1. Nf3 are equally good and none of them is better than others, even marginally. However, after 1. e4, both 1... e5 and 1... c5 are marginally better than 1... e6 and 1... c6; but none of 1... e5 and 1... c5 is better than the other. I am wondering if there is a way to theoretically prove this, either using an engine, or using statistics, or using opening theories.
So my question is: Can the following statement be proven?

After 1. e4, both 1... e5 and 1... c5 are marginally better than 1... e6 and 1... c6; but none of 1... e5 and 1... c5 is better than the other.

You can't really "prove" it. But, presumably, players want to play the best move, so which move is more often played may be an indication of which move the players think is best.
I looked at two databases with master games, and the most popular moves after 1.e4 in each were c5, e5, e6, and c6, in that order. This supports the first half of your statement (since e6 and c6 are played less often than e5 and c5) but not the second half (since c5 is played more than e5.)


"Back story" of the pieces legal moves An acquaintance whose family was from Turkey, told me that the pieces move the way do based on ideas about Persian warfare.  Moving in a rank or file was considered earthly, and moving diagonal was heavenly.

The king and advisor (queen) are combination of earthly and heavenly power. They are both equal in power, but the king can only move one space at a time, because he is burdened with the weight of command.

The pawns must move in an earthly way, but can only capture with the help of god (so the capture is diagonal like the bishop).

Everything else is fuzzy: There was something about why the pawn's first move could be one or two spaces.  I can't remember anything about the knights.  There was a reason rooks where earthly.  There was also a bit about why castling goes the way it does, and why pawns can be promoted.

Does this ring a bell with anyone?  It was a cool story, and I'd like to hear the whole thing again.

Your acquaintance is right, and wrong to some degree, since before chess went to Persia, its precursor is considered to have been invented in India. It was based on troop movements there, so they had already been established by then, even if they were later modified.

This is taken from Wikipedia here:

  Precursors to chess originated in India during the Gupta Empire.
  There, its early form in the 6th century was known as chaturaṅga,
  which translates as "four divisions (of the military)": infantry,
  cavalry, elephantry, and chariotry. These forms are represented by the
  pieces that would evolve into the modern pawn, knight, bishop, and
  rook, respectively."


Removing engine thinking (variations) in Arena Chess I setup a position in Arena. Then lets engine vs engine plays it after pressing 'Demo' button.
The problem is Arena put engine thinking as well into the moves list. (in green font). Check the screenshot.

How can I remove those marked in green font? I only want main moves (no variations or engine thinking).

Go to Options → Appearance → Movelist and under View uncheck "Show comments in the movelist". This should hide the engine thinking variations.
Alternatively, you can right-click in a move → Display → Comments.


What are the qualification criteria for the world team championship? The world team chess championship concluded recently and Russia won the Gold. But there were only ten countries that participated in the event. What are the criteria followed to select the countries participating in this event?

From the FIDE Handbook:

  1.4.1 Teams
   Qualification for the FIDE World Team Championship according to the following criteria:
   a.The previous event's World Chess Team Champion
   b.The three highest-placed teams in the FIDE Olympiad prior to the event.
   c.The four Continental Champions. The qualifiers will be the winners of the ultimate, respective Continental Championship organised at least six months prior to the World Team Championship.
   d.A team from the organizing federation.
   e.A team to be nominated by FIDE President.

  If any team would have already qualified according to one of these criteria, this place will be given to the next highest ranked country, in the Olympiad preceding the World Team Championship.


Arena Question - How Do I Set it So Arena Has a Time Limit But I Don't? I just download the arena chess program which is a chess playing GUI.  Frankly, I'm kind of lost.  I am trying to play chess games with the engines that come with it.  How can I set it so that the computer has a time limit for moves, but I don't?  It seems to default to "tournament" play mode.  I've tried just setting the time limit high, but then the software also takes a long time to move, which I don't want.  I would assume that many people would want to do this, but I cannot find the answer.

Version 3.5: I simply use from the menu: Levels/Adjust and from the dialog box select "Time per move". Whatever time you put in limits the computer's analysis time but of course you take as much time as you need to respond. :)

Of course same goes for "Fixed search depth".


When is it possible to carry out the "En Passant" manoeuvre? This manoeuvre is a form of pawn capturing technique. When a player’s pawn jumps two spaces on a first move, that piece can then be taken from the side as the opposing pawn moves into the moving pawn’s “lane” behind it, capturing it.

My question is, are there any other conditions where this move cannot be carried out such as to prevent check or checkmate or to carry out a check or checkmate?

Also, is this move allowed in tournaments and the like?

You can't take a pawn en passant if that pawn just made a discovered check to your King:

8/8/7k/8/2p5/8/3P4/2B1K3 w - - 0 1

1. d4+

After 1. d4+ Black is in check (their king is attacked by the White bishop on c1) so he has to move his King. 1...cxd3 is not allowed.

Also, it can't be carried out if your pawn is pinned to your king:

6k1/8/8/8/2p5/8/B2P4/4K3 w - - 0 1

1. d4

The Black pawn on c4 is pinned by the White Bishop on a2. If that Pawn moves, the White Bishop would be able to take the Black King. So after 1. d4 the move 1...cxd3 is not allowed.

I can't think of any other condition where this move can not be carried out.

And yes, en passant is allowed in tournaments of course. But when you take a pawn en passant, do not say "en passant" aloud (some low rated players do that, they also say "check" aloud when they put the other player's king in check) since it can break your opponent's concentration (and the concentration of the other players near you in the playing hall).

Wikipedia has a good article on the en passant rule.


Mac Desktop Client for FICS What are good chess clients for Mac, that allow playing on FICS. Nice-to-haves are an opening book, plug-and-play engines, and scoring of chess positions.

EDIT: For completeness, note that Jin does not allow you to save games. FICS can email them to you if you turn on a setting, but no way to recover guest games with Jin. I think this is a complete deal breaker.

You have choices:

i. Kibitz, implemented features are

Playing and observing chess games on FICS
Observing multiple games
Chat with other users on FICS
Support for chess variants including "Bughouse" and "Crazyhouse"

ii. Raptor, FICS desktop client for Mac

iii. Jin, which is Java based and can be executed on a Mac also.

iv. XBoard, a multi platform solution!

and such a pity that you can't try BabasChess (maybe you can use a emulator to execute it on your Mac)


Short and long term plans in a closed game in the Sicilian Defense Today, I have played a game as Black.

I reached this position, with Black to play:

The position, as you can see, is closed. The truth is that I had difficulty finding a plan here, considering the pawn structure, what are potential short and long term plans?

My Thoughts:
There are no open files yet and  the weakest point in White structure, which is located at d3, is by no means weak.

I considered moving a knight to g4 with the idea of exchanging with the dark-coloured bishop. But such an exchange would only put a pawn on e3, which would help White challenge the control of the dark squares. Thus, I quicky discarded this plan as I should be aiming to control the dark squares.

However, I am not sure what is the right plan. I guess that my plan should be preventing a d4 break by Qhite.

Can someone help me figure out a strategy for this game?

Note: I know that the computer suggests c4, but I am interested in a long term plan too. This is because, after that, there are no more breaks for me to aim for.

Before we talk planning, you can see from the diagram arrows that the tactical line 12.Nxd3 followed by c4 is available.   A trade of c&b pawns for Whites e&d pawns = the center is Blacks; not to mention the monster on b7 is unopposed.

On to abstract thinking:

  "I considered moving a knight to g4 with the idea of exchanging with
  the dark-coloured bishop but such exchange would only give a pawn on
  e3 which would challenge the control of the dark squares."

This line of thinking is extremely flawed!

Trading a knight for a bishop is rarely a bad idea.  Doubling the opponents pawns is also rarely a bad idea.
In this particular case it is a good idea!  Remember, doubled pawns have difficulty with mobility, and are therefore inherently weak.  What do you think controls more dark squares, the Bishop on e3 or a pawn on e3?

Now, in general when the center is fluid, you need to be thinking about the center.   "He who controls the spice controls the universe." and he who controls the center drives the battle.

So apart from the tactics available your planning should be around finishing development with an eye to conquering the center.

This position is so dynamic and full of tactics that it requires more concrete calculation than a long-term plan.

Edit due to comments -- more on fxe3 doubled pawns:
With resulting pawns on e3, e4, d3; yes the pawn on e3 controls f4 nicely, but look at the cluster -- it can't move!

The e4 pawn is attacked twice (so the d3 pawn is stuck) and it's advance is suicide.  Therefore the e3 pawn isn't going anywhere either.

So now black can make long-term plans.  Piling up behind the c-pawn to play c5-c4 can result in White getting double-isolated-pawns on the efile.   Or setting up a battery of Bb6 and Qa7 hitting the weak e3 pawn...  There are various ways for Black to attack due to Whites weakened structure.  Now what can White do?  Looks like just defend.  His knights have no active squares and his remaining Bishop is thwarted.  White is clearly worse here.


What is the theory behind center control? Center control is an important aspect of playing chess, most openings are built around controlling the center, but why? Is center control really that important for winning a game?

The center is the crossroads of the board. Controlling it will give you access to every other part of the board. At the same time, it will drive a wedge in the opponent's position that hampers communication between king and queen side.

Control of the center is usually a decisive advantage in your favor; unless your opponent has heavy compensation (e.g. more than a pawn of material advantage), or a violent attack against your king.


Checkmate with only relevant pieces What is the maximum number of black and white pieces which are relevant in a checkmate position (by White)? That is if any piece (black or white) was removed from the board, the checkmate would not be possible because that piece is relevant or has a role in such checkmate position because it may be: (1) checking the king (2) blocking a square where the checked king can move (3) attacking the unoccupied square where the checked king can move (4) preventing the king or other pieces to capture or block the checking piece. (Note that there shall be no idle or useless piece including the White king)

Addendum 5/27/2021-Using @Hauke's Reddmann's position as a plagiarised base, 20 pieces is indeed feasible!
[FEN "1B2R2B/1Nq1bK2/2p2n2/Q3k3/5n2/1N2bP2/1r5B/B3R3 w - - 0 1"]

I found another, far funnier, reason why a piece can't be removed; the position would otherwise be illegal!
Using this idea, I've managed 19 pieces. White's pieces can't be taken, with the White king unmoveable, or else the checkmate is null. Black's pieces prevent illegality and "guard" c4, minus the e6 block.
 [FEN "8/2B1R3/1N1rnp2/1Qq1knR1/2pP1r2/2K1bPB1/4R3/8 w - - 0 1"]


Personal chess database I'm looking for non commercial program where I can import PGNs. And to visualize the games I want simple GUI and analysis-table like you will find here. Additionally it would be nice if the program provides an interface where I can write my own statistics.

What I found was gnu chess, sunfish and jose. But those programs are more then I'm looking for.

SCID does everything you are looking for, it's great chess database software.


Meeting d4-d6 from White's perspective How do you meet d4-d6 when your opponent doesn’t play the Old Indian, and the setup is d6-Nbd7-e5, which is Pirc territory?

[fen ""]

1. d4 d6 2. null Nd7 3. null e5

When this happens, can I play the London System, possibly with d4-Bf4, and so forth?

Planning to play the Old Indian (Be7 for black) against the London System has no bite since white can control e5 more easily. The Be7 does not aim at e5, of course, but as important, it inhibits Re8, and its control of e5 also. So minus two pieces helping play e5, and you are not likely to get that freeing move in. You would also have to play (after d6) e6 since e5 loses a pawn to any reasonable white development, Be7, and only then, figure out how to enforce e5 gaining some space in the center. In reality, you would probably have to play for c5 instead.

As a defense against the London System, the King's Indian (g6 and Bg7) is much more logical since the Bg7 can help fight for control of e5, and the Re8 immediately helps too with a potential e5. In those lines, white usually plays Bf4, but then h3, and Bh2 to anticipate black's eventual e5.


How did castling originate? Castling to me has always seemed like such a huge leap in terms of game play that I've always wondered how it came to be.

Does anyone know the history behind how and why castling came to be?

Per Wikipedia:

Castling was added to European chess in the 14th or 15th century and did not develop into its present form until the 17th century. The Asian versions of chess do not have such a move.

The King seems to have always moved the same as at the present, except that the game used to be played until he was actually captured. Because of the King's vulnerability due to the Queen's enormous scope and power, several methods of "castling" were tried before the 16th century.

One method was to allow the King to move two or three squares on its initial move.
Another method was to allow the King to move directly to g2.
The present method of castling was documented as early as Ruy López's 1561 work Libro de la invención liberal y arte del juego del Axedrez.


A rook up, can black end the checks and thereby win (LiChess.org puzzle 74754)? A LiChess.org puzzle ends at this position with white to move.  Apparently, black has a win here, but running through moves with LiChess's Stockfish, I can't seem to figure out how to end the checks.

[FEN "1K6/PPPq2PP/5P2/3p4/1p2Q3/7p/8/k2r4 w - - 0 1"]

Question: Can black end the checks and win?

Maybe there's a humanly understandable reason that the checks don't end.  Or maybe the web version of Stockfish is not looking deep enough.

Looks like you are correct with your second assumption - the evaluation didn't (cannot) look deep enough.

It's a classic application of the horizon effect.

The white queen essentially has half of the chessboard at her disposal to give checks, while the black king has no shelter (the single rook is not enough (but moving it every now and then will reset the 3-fold-repetition countdown) and the black queen is cut off) but a lot of space to run around. The pawn on g5 will fall with check at some point and reset the 50-move countdown, too. The number of lines increases exponentially and since none of them actually changes anything significant about the position, Stockfish cannot efficiently prune any of them. Thus the search tree grows too large to process even for a modern engine on presumably good hardware.

PS: I've tried and removed the white pawns and the black pawn on g5 who look insignificant to the perpetual at first glance to reduce the number of chessmen to 7 - low enough to use Lichess' tablebase. And indeed, that position is won for black. However, this is meaningless as both sides will quickly play moves that are impossible in the puzzle position, e.g. the white queen will move to a1 and the black king will run towards e3.


When and why was en passant invented? Other than castling, the only "strange" move that chess pieces can ever make is en passant.  It seems a little odd to me that someone thought that such a "different" move was so important to include in the legal moves.  When and why did this come to be?

From Wikipedia:

Allowing the en passant capture is one of the last major rule changes in European chess that occurred between 1200 and 1600, together with the introduction of the two-square first move for pawns, castling, and the unlimited range for queens and bishops (Davidson 1949:14,16,57). Spanish master Ruy López de Segura gives the rule in his 1561 book Libro de la invencion liberal y arte del juego del axedrez (Golombek 1977:108). In most places the en passant rule was adopted as soon as the rule allowing the pawn to move two squares on its first move, but it was not universally accepted until the Italian rules were changed in 1880 (Hooper & Whyld 1992:124–25).
The motivation for en passant was to prevent the newly added two-square first move for pawns from allowing a pawn to evade capture by an enemy pawn. Specifically, the rule allows a pawn on a player's fifth rank the opportunity to capture the opponent's pawn on an adjacent file that advances two squares on its first move as though it had advanced only one square (Davidson 1949:16). Asian chess variants, because of their separation from European chess prior to that period, do not feature any of these moves.


About stalemates and how to cause one Are their possible positions where the 'white' side is losing but the person is in a  situation where they can force a stalemate? Are there chess positions one can 'look out for' to enable one to force a stalemate if 'needed'?

Well, if the player can force stalemate, then he isn't lost. So the strict answer is no :-)

There are many elementary endgames where a successful defence is possible only because of stalemate, like king + pawn vs pawn:

[FEN "8/3k4/8/2KP4/8/8/8/8 b KQkq - 0 1"]

1...Kc7! 2.d6+ Kd7 3.Kd5 Kd8 4.Kc6 Kc8 5.d7+ Kd8 Kd6 =

or king + queen vs king + pawn with the pawn on the c file:

[FEN "7K/8/6Q1/8/8/8/2p5/1k6 w KQkq - 0 1"]

1.Kg7 Kb2 2.Qb6+ Ka1 3.Qc5 Kb1 4.Qb4+ Ka1 5.Qc3 Kb1 6.Qb3+ Ka1!

and if white takes the pawn now, it's stalemate, so he can't progress.


How do endgame tablebases calculate checkmates to do retrograde analysis on? I understand that once endgame tablebases get checkmates, they do retrograde analysis and are able to calculate forced wins. However, how do they calculate the checkmate in the first place? Do they just use brute force?

Yes, endgame tablebases are calculated by brute force. That's why we only have complete 7-men tablebases today (which were published in 2012).
When stockfish finds a mate with more pieces than stockfish has calculated until only 7 men are on the board and the tablebases give stockfish the solution for the rest.


Can Magnus Carlsen force draw (pun-intended) himself to victory? So far Carlsen has a 2 game lead over Anand and there are only 4 games left.  At the strength of these players, can Magnus basically force his opponent into draws by playing certain openings or styles?  Can he force Anand into drawing the rest of the games to win the world championship?

It depends what you mean by "basically". He cannot actually force a draw in any given game (otherwise he would have started doing it already, as soon as he won one game). However he can play drawish lines; the variation he went into in game 8, for example, is almost never lost by White at top levels.

It's going to be difficult for Carlsen to "force" a draw if Anand plays something sharp like the Dutch or Pirc. His optimal strategy is still pretty much to just continue to play good chess.


Can King take piece end up threatened? In this position black queen defended by pawn checked white king. Is it possible if the white king take black queen and end up threatened by black pawn?

Assume the image was taken from Black's side (otherwise the queen is not protected).

No. The Black queen is protected by the black pawn, and thus can't be taken by the White king. The only possible move is to move the king to the other direction one square.


Fastest King vs King endgame What is the fastest possible game that ends in a King vs King endgame? Please post a game and tell me the number of half-moves you've achieved. By some simple logic, I can prove that this number is greater than 32 half-moves. There are 30 pieces to be captured, and the first capture can only be made on the 3rd half-move or later.

An example of such a game could be this:

[FEN "rnbqkbnr/pppppppp/8/8/8/8/PPPPPPPP/RNBQKBNR w KQkq - 0 1"]
1. e4 d5 2. exd5 c6 3. dxc6 Qa5 4. cxb7 Qxa2
5. bxa8=Q Qxa1 6. Qxa7 Qxb2 7. Qxb8 Qxb1 8. Qh5 Qxc2
9. Qxh7 Qxc1+ 10. Ke2 Qxd2+ 11. Kf3 Qe1 12. Qxh8 Qxf1
13. Qxg7 Qxg1 14. Qxg8 Qxh1 15. Qxf7+ Kd7 16. Qxf8 Qxh2
17. Qxe7+ Kxe7 18. Qxc8 Qxg2+ 19. Ke2 Qxf2+ 20. Kxf2 Kd6
21. Qd7+ Kxd7
1/2-1/2

achieving the result in 42 half-moves.

This is a famous task, originally tackled by Sam Loyd and only improved a century later.  See http://www.chessvariants.com/problems.dir/twokingstask.html, which gives the refinement by Ponzetto:

[FEN "rnbqkbnr/pppppppp/8/8/8/8/PPPPPPPP/RNBQKBNR w KQkq - 0 1"]
1.e4 d5 2.exd5 Qxd5 3.Bd3 Qxa2 4.Bxh7 Qxb1 5.Bxg8 Qxc2 6.Bxf7+ Kxf7 7.Rxa7 Qxc1 8.Rxb7 Rxh2 9.Rxb8 Rxg2 10.Qxc1 Rxg1+ 11.Rxg1 Rxb8 12.Qxc7 Rxb2 13.Qxc8 Rxd2 14.Qxf8+ Kxf8 15.Rxg7 Rxf2 16.Rxe7 Kxe7 17.Kxf2

For reference, here's the original Loyd solution:

[FEN "rnbqkbnr/pppppppp/8/8/8/8/PPPPPPPP/RNBQKBNR w KQkq - 0 1"]
1. c4 d5 2. cxd5 Qxd5 3. Qc2 Qxg2 4. Qxc7 Qxg1 5. Qxb7 Qxh2 6. Qxb8 Qe5 7. Qxc8+ Rxc8 8. Rxh7 Qxb2 9. Rxh8 Qxa2 10. Rxg8 Qxd2+ 11. Kxd2 Rxc1 12. Rxg7 Rxb1 13. Rxf7 Rxf1 14. Rxf8+ Kxf8 15. Rxa7 Rxf2 16. Rxe7 Rxe2+ 17. Kxe2 Kxe7

[ ETA: Incidentally, while the linked article leaves it as an open problem, it seems like it would be a very straightforward task to show that 16.5 is optimal; at least at first glance I don't see any lines that have captures by both sides on all four half-moves in moves 2 and 3, which would imply that some form of 'off move' along the lines of White's 3. Bd3 is a strict necessity within the first few moves. ]


English opening against Dutch defense How do the two systems work against each other? In particular, let's say I'm playing white, and the opponent has played e7-e5 after a Bird-like opening:

[fen "rnbqkb1r/pppp2pp/5n2/4pp2/2PP4/2N5/PP2PPPP/R1BQKBNR w KQkq e6 0 4"]

Are there any theoretically studied variations here that lead to determined outcomes?

This isn't necessarily an answer; it's some amusing searches and information that might help others get a "real" answer.  (It just seemed too much for a comment.)

I'm not familiar with this setup, so I resorted to "Google-fu".

A quick Google search found A10 English, Anglo-Dutch defense.  Following forward with 2. Nc3 Nf6 3. d4 e5 shows only a single game (but see below): Haring vs. Freiberger, at the Werther 2000.  One game is not going to give you much theory to go on...

My search was simply "1. c4 f5", for those wishing to play along at home.  Hopefully those 365chess.com links work for people without accounts; it's free, but they sometimes hide things behind log in screens...

I've found that 365Chess.com's game database isn't the most robust, so I did some more searching, and found this pdf claiming this is the Rittenhouse gambit, with 5 games played (all with dates between 1972 and 2001, inclusive).

Unfortunately, that's where my trail led dry... I'm finding several links online of people calling this the Rittenhouse gambit, but no real information ON the Rittenhouse gambit.

Good luck!


Alpha Zero vs Lc0 - time for self-play Alpha Zero defeated Stockfish after only 9 hours of self-play. On the other hand, Lc0, has been training for several months and while attaining impressive strength (to say the least...) it's still not crushing Stockfish. What can be the reason for such a dramatic difference in learning efficiency?

In short, because DeepMind has TPUs. Lots and lots of TPUs.

By far, the most time-consuming part of the training process is generating self-play games. DeepMind used 5000 TPUs to generate self-play games, which is a lot of processing power. Meanwhile, Lc0 crowdsources processing power from volunteer clients, which is much slower.

From the DeepMind paper published December 2017 (emphasis mine):

  We trained a separate instance of AlphaZero for each game. Training proceeded for 700,000 steps (mini-batches of size 4,096) starting from randomly initialised parameters, using 5,000 first-generation TPUs to generate self-play games and 64 second-generation TPUs to train the neural networks.

To achieve the level of performance that AlphaZero got against the (sub-optimally tuned) Stockfish version 8, the training run took about 9 hours and 44 million self-play games for chess:

Meanwhile, the Lc0 project got started sometime in January 2018, and by April 2018, they'd only generated 8.2 million out of the needed 44 million games. I believe they were generating about 200k games per day at the time.

They also came across a lot of bugs in the process and were figuring out a lot of things as they went, so when the first training run plateaued, the best net was not as good as AlphaZero. Since then, the Lc0 project has actually restarted the training run multiple times:

old main: The original 192x15 "main" run, using the original lczero.exe engine. It ended in August 2018, with the last net being ID595. (These nets don't seem to be listed anymore though? The early IDs at the bottom of the net list seem to be these test nets.)
test10: The original 256x20 test run. This was a separate pipeline using a completely rewritten lc0.exe engine that was much faster at generating self-play games. Net numbering for this run started with ID10000 on June 27, 2018, and ended with ID11262 on August 30, 2018.
test20: A run with various changes, starting with ID20001 on August 30, 2018 and ending with ID22201 on November 16, 2018.
test30: A run testing various new ideas, starting with ID30001 on September 9, 2018. As of January 14, 2019, the best net was ID32598.
test40: The December 6, 2018 AlphaZero paper revealed a lot of differences between what DeepMind did and what Lc0 did, and it looks like a new test run started with ID40001 on January 8, 2019. As of January 14, 2019, the best net was ID40202.

To get a sense of how well Lc0 is doing compared to AlphaZero, it's more useful to look at the Elo with respect to total number of games generated, not time elapsed. Here's what the graph looks like for the entire Lc0 project as of January 14, 2019 (note that this is self-play Elo, which is inflated compared to actual Elo):

As you can see, they've reset the training run many times. There were also a number of bootstrap mini-resets during the original main run to fix some critical bugs, and there was also a temporary test35 to test the newly revealed configuration settings from the December 2018 AlphaGo paper. Yep, this isn't confusing at all! (/s)

There are lots of calculations and graphs in this spreadsheet here that compares lc0's performance with AlphaZero. For example, here's the graph from the first old main run (under the "Graphs" tab):

From that link, an explanation of what "Leela Max" is:

  "Leela Max" is Leela's theoretical maximum performance when given hardware and/or time to the point of absolute diminished returns. It may be more comparable to AlphaZero, as AlphaZero operated on 4.8 million nodes per move, whereas a conventional setup only gets a small fraction of that.

These days, the self-play generation speed is much faster than it was at the beginning. As of January 14, 2019, it looks like the project is generating about 1.5 million games per day. But at this speed, it'll still take a month to achieve what DeepMind achieved in 9 hours. More like double the time, really, if the training games are being diverted towards two separate runs.


Analysis on Alekhine-Lasker 1934, after 18.Qd6 In this position from Alekhine-Lasker, Zurich 1934

[fen "r4rk1/pp3ppp/1qpQ1n2/4nN2/8/1B2P3/PP3PPP/2R2RK1 b - - 0 1"]

1... Rae8 2. Ne7+ (2. Rc5 Nfd7) Kh8 3. Qxe5 Ng8

It's Black to play. So  if 18...Rae8, then how can White continue to get an advantage?
If 19.Ne7+ Kh8  20.Qxe5 Ng8, Black seems to get the piece back with a good position.
Also 19.Rc5 Nfd7 doesn't seem to lead anywhere. I'm I missing anything here?

After 20...Ng8 21. Nc6! Re5 22. Ne5 and wins f7 too due to the dual threats of Nd7 and Nf7, both winning the exchange. So, 22...Nf6 is forced, and white is just winning there.

It is going to be Q vs. R, B, and two pawns; but the problem is that white will control both files, and the black K is still not safe.

[fen "r4rk1/pp3ppp/1qpQ1n2/4nN2/8/1B2P3/PP3PPP/2R2RK1 b - - 0 1"]

1... Rae8 2. Ne7+ (2. Rc5 Nfd7) Kh8 3. Qxe5 Ng8 4. Nxc6! Rxe5 5. Nxe5 Nf6 {forced} 6. Nf7 Kg8 7. Rfd1 {is crushing since you cannot take on f7 due to mate with Rc8}


The record for most consecutive moves by a piece in a FIDE rated (it's FIDE at the least) event is 80 moves by a rook, starting on move 67. It happened in the game Yueh Wei Po- Arora during the 37th Chess Olympiad. It was a draw in the end. This record is on Tim Krabbe's page for chess records of course.

 [Title "Yueh Wei Po-Arora, 37th Chess Olympiad, Turin Italy, 6/2/2006"]
 [FEN ""]
 [startply "133"]

1. d4 Nf6 2. c4 g6 3. Nc3 Bg7 4. e4 d6 5. Nf3 Bg4 6. Be2 O-O 7. O-O Bxf3 8. Bxf3 c6 9. Be3 Nbd7 10. Qd2 Qc7 11. a4 a5 12. Be2 e5 13. dxe5 Nxe5 14. f4 Neg4 15. Bxg4 Nxg4 16. Bd4 f5 17. Bxg7 Kxg7 18. Qd4+ Kg8 19. Rad1 Rad8 20. exf5 gxf5 21. h3 Nf6 22. Rfe1 d5 23. cxd5 Nxd5 24. Nxd5 Rxd5 25. Qc4 Qf7 26. Rxd5 cxd5 27. Qd4 Rc8 28. Rd1 Rc4 29. Qxd5 Qxd5 30. Rxd5 Rxf4 31. Rxa5 Rb4 32. Rb5 Rxa4 33. Rxb7 Rd4 34. Kf2 Rd3 35. Ke2 Rg3 36. Kf2 Rd3 37. b4 Rb3 38. b5 Kh8 39. b6 Kg8 40. g3 h6 41. h4 Kh8 42. Rb8+ Kg7 43. b7 Kh7 44. Ke2 Kg7 45. Kd2 Kh7 46. Kc2 Rb4 47. Kc3 Rb1 48. Kc4 Kg7 49. Kd5 Rb3 50. Ke5 Rb5+ 51. Kd6 Rb3 52. Kc7 Rc3+ 53. Kb6 Rb3+ 54. Kc5 Rb1 55. Kc4 Rb2 56. Kc3 Rb1 57. Kc2 Rb4 58. Kc3 Rb1 59. Kd4 Rb2 60. Ke5 Rb5+ 61. Ke6 Kh7 62. Kf6 h5 63. Kg5 Kg7 64. Kxh5 f4+ 65. Kg4 fxg3 66. Kxg3 Kh7 67. Kg4 Rb4+ 68. Kg5 Rb5+ 69. Kf6 Rb6+ 70. Ke7 Rb4 71. Kd7 Rb2 72. Kc7 Rc2+ 73. Kb6 Rb2+ 74. Kc5 Rb1 75. Kc4 Rb2 76. Kc3 Rb1 77. Kc2 Rb4 78. Kc3 Rb1 79. Kd4 Rb2 80. Ke5 Rb1 81. Kf6 Rb6+ 82. Kf7 Rb1 83. Ke7 Re1+ 84. Kd6 Rd1+ 85. Kc5 Rc1+ 86. Kb4 Rb1+ 87. Ka5 Ra1+ 88. Kb4 Rb1+ 89. Ka3 Rb5 90. Ka2 Rb4 91. Ka3 Rb1 92. Ka4 Rb2 93. Ka5 Rb1 94. Ka6 Ra1+ 95. Kb6 Rb1+ 96. Kc7 Rc1+ 97. Kd8 Rd1+ 98. Ke8 Re1+ 99. Kf8 Rf1+ 100. Ke7 Re1+ 101. Kf6 Rf1+ 102. Kg5 Rb1 103. Kf6 Rb6+ 104. Kg5 Rb5+ 105. Kg4 Rb4+ 106. Kf3 Rb3+ 107. Ke4 Rb4+ 108. Ke5 Rb1 109. Kd4 Rb2 110. Kc3 Rb6 111. Kc4 Rb1 112. Kd4 Rb4+ 113. Kc5 Rb2 114. h5 Rb1 115. Kd5 Rb2 116. Ke6 Rb1 117. Kf6 Rb6+ 118. Kg5 Rb5+ 119. Kg4 Rb4+ 120. Kf5 Rb5+ 121. Kf4 Rb4+ 122. Kg3 Rb3+ 123. Kf2 Rb2+ 124. Ke3 Rb3+ 125. Ke2 Rb2+ 126. Kd3 Rb3+ 127. Kd4 Rb4+ 128. Kc3 Rb1 129. Kd4 Rb2 130. Ke3 Rb1 131. Kf2 Rb2+ 132. Kf3 Rb3+ 133. Ke2 Rb2+ 134. Kd3 Rb1 135. Kd4 Rb2 136. Ke5 Rb1 137. Kf6 Rb6+ 138. Kf5 Rb5+ 139. Ke6 Rb4 140. Rf8 Rxb7 141. Rf5 Ra7 142. Kf6 Rb7 143. Kg5 Ra7 144. h6 Rb7 145. Kh5 Ra7 146. Rg5 Rb7 147. Rc6 1/2-1/2


Which is MCO book by Walter My mom is going to chess classes for some years now. Am absolutely noob. She has been asked to buy a book: "Modern Chess Openings" by Walter Korn. While googling, I came to know that the author of this title is changed over edition.
Till MCO12, it seems that it was completely written by Walter:

MCO13 says "Revised by Nick De Firman, under the editorship of Walter":

Now MCO14, 15 completely erases Walter's name from the book:

Is the content of the book considerably changed over these editions. Which one should I prefer?

The MCO series is styled like an encyclopedia. Just how encyclopedia's tended not to change all that much from one year to the next, the MCO series hasn't changed all that much.

I would balance price with target audience rating. If the target audience rating is high, then spend more on the latest MCO. If the target audience rating is low, save money on a second hand, older MCO.

This advice is based on the fact that at lower levels, opening theory isn't all that important, so paying a lot of money for an opening encyclopedia doesn't make much sense.

One final note is that openings come in-and-out of fashion. You may find that differences in MCO editions over time reflect more the level of popularity of an opening rather than any substantial changes to chess theory.


Why does a chess engine not get excited about a piece exchange at the end of its analysis depth? I read about the chess engine algorithms and came up with a question. If, for example  roughly all (disregarding alpha-beta pruning) possible 20 moves variations are calculated, why does a chess engine not consider a piece exchange on move 20 winning? It seems to me that to an evaluation function the final position will seem like one player is just up a piece. How do they solve this problem?

Chess engines will always try to extend the search by a few moves, so a position is only evaluated if it is considered "quiet". This is called Quiescence Search, and the problem you describe that it is trying to prevent is called the "Horizon effect".
So before evaluating a position, if there are captures, checks and so on in the position, then the search is first extended by those moves.


Is there any GUI for Stockfish which allows comments in macOS Big Sur? Currently I use the built-in Stockfish app that's in the Apple Store. But unfortunately, I can't put comments in the moves. I would really appreciate it if you can give me good recommendations other than ScidvsMac, because after updating to Big Sur, it doesn't work anymore.

I found ChessX to be working well. I can put comments in the moves. But I still don't know how to make the depth of Stockfish to run more than 20! It only runs for 3 seconds, then it stops. If I can figure out how to make it run longer, I would be happy with ChessX.
Edit: You can slide the bar at the bottom right corner to make the search deeper


Queen's Gambit Declined: Alatortsev variation, is there a high quality resource covering this line? I am working on my opening repertoire, and I need ways to dodge the Exchange variation of the Queen's Gambit Declined with Nge2. Many masters use the Alatortsev variation to do this.

After the following moves:

[fen ""]

1.d4 d5 2.c4 e6 3.Nc3 Be7

We get the tabya of the above mentioned line.

There are many books about QGD that cover this line, but none does that in full detail.

Furthermore, browsing through Internet I found that there were some important theoretical novelties at the top level which were not mentioned in modern books about QGD. Unfortunately I can not provide the links now since it was more than 3 months since I last saw them.

So my question is following :

Is there a book or an online resource that covers this line in great depth with high-quality analysis?

Thank you.

Best regards.

Be7 avoids the QGD Exchange Variation and usually moves towards either an exchange with Bf4 or a regular QGD. If it's a regular QGD, there obviously won't be any books dedicated specifically to this variation as it will transpose to another well-known line.

The only pressing line then is the one with cxd5 and Bf4. I can't recall any books that focus specifically on this line in depth, but there have been many games played at the international level that use this variation. I would recommend exploring game databases like MegaBase and finding annotated games.


Was this sacrifice a good one? Upon reviewing a game I played. I started to feel bad about exchanging my attacking bishop for my opponent’s useless one. But I believe that I had no other choices. I want your opinion about what I should have done in this situation.

I am a 1200 rated player on chess.com

[FEN ""]

1.e4 e5 2.Nf3 f6 3.d4 d6 4.dxe5 dxe5 5.Qxd8+ Kxd8 6.Bc4 Nh6 7.O-O a6 8.a4 Nd7 9.Nc3 c6 10.b4 Bxb4 11.Na2 Bf8 12.Bd2 Nf7 13.Bxf7 Nc5 14.Ba5+ Kd7 15.Rfd1+ Ke7 16.Bb3 Nxe4 17.Rd8 b6 18.Bxb6 Rb8 19.Rad1 Rxb6 20.Rxc8

In the end I won by checkmate because he blundered. What I want to know is how should I handle positions where my opponent is just attacking my attacking pieces. Additionally, please try to find where my weak points are in the game.

Given that you are a piece up with a dominating position, exchanging the bishops isn't a problem at all. Note, that it is just an exchange, not a sacrifice.

You could have played 19.Bc7 instead, in that case black has to react 19…Ra8 or he will lose even more material (for example 19…Rb7 20.Rxc8 Kd7 21. Rxf8 with three pieces for a rook, which is a bit much …).

Concerning your weaknesses:

Only 10.b4 strikes me as truly bad, blundering a pawn and misplacing your knight. And 15.Nc3 would have prevented your second pawn blunder.

So you won this game because your opponent blunders pieces whereas you only blunder pawns. Stop blundering pawns and you'll start beating those players that blunder pawns. And then we'll talk about why 2…f6 is a bad move and how to punish it.


Knights on c3 & f3, bishops on d3 & e3 - what is this called, and is it sound? Sometimes when opening I fall into this odd rut of developing knights to C3 and F3, and bishops to D3 and E3. (Or, as black, C6, F6, D6 and E6). For instance, the position after 7.Be3:
[FEN ""]
[Event "Rated Blitz game"]
[Site "https://lichess.org/BPXlGMH2"]
[Date "2021.05.19"]
[White "stevage"]
[Black "Rodeon0049"]
[Result "0-1"]
[UTCDate "2021.05.19"]
[UTCTime "02:54:05"]
[WhiteElo "1655"]
[BlackElo "1811"]
[WhiteRatingDiff "-3"]
[BlackRatingDiff "+4"]
[Variant "Standard"]
[TimeControl "0+5"]
[ECO "A40"]
[Opening "Modern Defense"]
[Termination "Normal"]
[Annotator "lichess.org"]

1. d4 g6 { A40 Modern Defense } 2. c4 Bg7 3. Nc3 c6 4. e4 d6 5. Bd3 Nf6 6. Nf3 Bg4 7. Be3 Bxf3 8. Qxf3 O-O 9. O-O e5 10. d5 cxd5 11. cxd5 Na6 12. Bg5 Nb4 13. Be2 Nc2 14. Rac1 Nd4 15. Qg3 Qb6 16. b3 Rac8 17. Na4 Nxe2+ 18. Kh1 Nxg3+ { White resigns. } 0-1

Does this structure have a name? It seems it could arise in response to a number of different openings.
Does it have any particular merit? What are its weaknesses?
I'm not really sure what to think about it - I sometimes fall into this pattern when my opponent plays quiet developing moves that don't engage the centre.

I don't know a specific name to it, but what concerns the downsides of this setup, I could think of two. Of course, it is very situational, but since in the example black opted for a kings-indian setup, it is that 1) the bishop on d3 is rarely useful against the fianchetto (pawn on g6 is well protected), and 2) it blocks the d-file which sometimes can lead to weakening of the d4 pawn and/or square. For example, there is a line in KID where white plays Bd3 and Nge2, and one of the black's possible responses is Nc6 and e5, and he's ready to meet d5 with Nd4. This would be impossible in a classic white setup with the light-square bishop on e2.


Why is this position stalemate? I'm new to chess Why is this position stalemate? I'm new to chess and I played white.

Black is not in check (which would make the position checkmate) but black has no legal move. This results in a type of draw known as stalemate.


What is the best reply to Qe5+/Qe6+ in Scandinavian? [FEN ""]
1.e4 d5 2.exd5 Qxd5 3.Nc3 Qe5+ ( 3... Qe6+ )

What is the best reply to this ? I know that it isn't very good move for black, but I met it few times. I thought that Be2 is the best because other moves block bishop and it is bad later in the game. Am I right ?

Keeping the queen in the center vulnerable to attack cannot be Black's best option. Be2 is the obvious move for reasons you gave. Black can't exploit it, and while e2 is not the best of squares for the bishop, it's still development.

David Letterman played the 3...Qe6+ line against Kasparov in a televised game. Kasparov played 4. Be2, and after 4...Nc6 5. d4 Qg6 5. Nf3 Qxg2 6. Rg1 Qh3 he had a massive lead in development. This is the line I'd go for against Qe6.

3...Qe5+ is just as bad since a future Nf3 will gain another tempo. 3...Qe5+ 4. Be2 c6 (or where is black going to put the queen after Nf3?) 5. Nf3 Qc7 and white again has a massive lead in development.


Is it possible to reach King vs King by moving each piece at most twice? I'm interested in short games that reach a King vs King endgame. Sam Lloyd reached King vs King after only 17 moves. This has since been improved to 16.5 moves. (See this and that.) One can show that this is optimal. In these games, almost all captures are performed by queens and rooks, but I'd like to see a massacre with more diverse captures.
Question 1: Is it possible to reach a King vs King endgame by moving each piece at most twice?
Notice that you can't get away with moving each piece at most once, since this would give King vs King in only 16 moves.
Question 2: Assuming such games exist, what's the shortest game?
Please post a game and report the number of moves.

Answer 1: Yes, this is possible.  Here is an example game in 27 moves:
[FEN ""]

1. a4 a5 2. b4 b5 3. bxa5 bxa4 4. Rxa4 Nc6 5. g4 Nxa5 6. Rxa5 Rxa5 7. h4 g5 8. hxg5 h5 9. gxh5 d5 10. c4 Nf6 11. cxd5 Nxd5 12. e4 Bb7 13. exd5 Bxd5 14. Nc3 e6 15. Nxd5 exd5 16. Bg2 c5 17. Bxd5 Rxh5 18. d4 Rxg5 19. dxc5 Bxc5 20. f4 Bxg1 21. Rxg1 f6 22. fxg5 fxg5 23. Rxg5 Qxd5 24. Ke2 Qxd1+ 25. Kxd1 Rxg5 26. Bxg5 Kd7 27. Bd8 Kxd8

You can even insert some moves that slow the game down so that every piece moves exactly twice.  Sadly, this is the opposite of your second question.
[FEN ""]

1. a3 a6 2. a4 a5 3. b4 b5 4. bxa5 bxa4 5. Rxa4 Nc6 6. g4 Nxa5 7. Rxa5 Rxa5 8. h4 g6 9. Nh3 g5 10. hxg5 h6 11. Ng1 h5 12. gxh5 d6 13. c4 d5 14. Qc2 Nf6 15. cxd5 Nxd5 16. e4 Bb7 17. exd5 Bxd5 18. Nc3 e6 19. Nxd5 exd5 20. Bg2 c6 21. Qd1 c5 22. Bxd5 Rxh5 23. d4 Rxg5 24. dxc5 Bxc5 25. f4 Bxg1 26. Rxg1 f6 27. fxg5 fxg5 28. Rxg5 Qxd5 29. Ke2 Qxd1+ 30. Kxd1 Rxg5 31. Bxg5 Kd7 32. Bd8 Kxd8


Openings Recommendations to Study for Unrated Tournament In little over a month I am planning on playing an unrated tournament.  Since it is unrated I am assuming the skill level could possibly be from novice to strong.  Due to the entry fee being very low I don't expect masters to be playing. My own play level, for discussion's sake, is amateur.

What openings would be recommended to study in preparation?  I would like to build a repertoire for this event.

I would personally stick to learning a few e4 and d4 variations and maybe the English Opening, though I didn't see it much at lower level play. I am also adding some fun, fairly solid variations if you wanted try the more obscure openings

Ruy Lopez
1. e4 e5
2. Nf3 Nc6
3. Bb5

A personal favorite of mine, especially the Rio Gambit Accepted line 1.e4 e5 2.Nf3 Nc6 3.Bb5 Nf6 4.O-O Nxe4, but in general it can create early control of the center and can lead to a strong position with an active bishop or forcing black to double pawns

Not my preference, but I used to see a lot of the Giuoco Piano

e4 e5  2. Nf3 Nc6  3. Bc4 Bc5

and the Giuoco Pianissimo

e4 e5  2. Nf3 Nc6  3. Bc4 Bc5 4. d3

I wouldn't stress studying this one

Sicilian Defense
1. e4 c5

It's rare for me not to see this opening.

Sicilian Sveshnikov
1.e4 c5
2.Nf3 Nc6
3.d4 cxd4
4.Nxd4 Nf6
5.Nc3 e5
6.Ndb5 d6.

It gives a menacing knight position to white, but allows you to prepare your pieces for development and gains a general grasp in the center

Sicilian Dragon
1. e4 c5
2. Nf3 d6
3. d4 cxd4
4. Nxd4 Nf6
5. Nc3 g6

Can create very aggressive and constricting pawn marches for white and a fianchettoed bishop and free queen for black. This is very aggressive and loads of fun to play

English Opening
1. c4

A very flexible and reliable opening if you are well studied into it.

King's Gambit
  1. e4 e5  2. f4

A sacrificed pawn for quick development. What's not to like

A few others you could also look into are the Pirc Defense, Indian-Defenses, Queen's Gambit, Caro-Kann


Is this a stalemate? The gamepigeon app is declaring I lost (I am black). This simply does not make sense since it is white's turn and they are in check. The game abruptly ends.

Is this erroneous logic? How can I lose if I am not in check?

This is a bug. The GamePigeon app was written by non-chess programmers, their focus is not on chess. They're not specalized in chess apps, chess is just one of the many things they do.


Chess960 or Chess959? Once in 960 times, chess960 should just be the same as regular chess. Are there any known instances of this? Or is this selection automatically excluded and they just roll the dice again? So is it really "Chess959"?

EDIT: Found this: https://lichess.org/forum/lichess-feedback/chess960-starting-position-518-is-like-regular-chess. An online player complains that he has faced the dreaded 518 two times. And why not? My golfing uncle hit two holes-in-1 during his career, and that’s got to be a lot less likely than 1 in a thousand!

But I think that Chess960 can’t be that popular at top levels or there would be a celebrated example where GM X faced GM Y over a 518 Game Array.

There is no mention of excluding the regular starting position in Appendix F. of the FIDE Laws of Chess, so it's really Chess960 and not Chess959. I can imagine that there are chess programs or websites which do exclude the regular starting position, but this is against the official rules.


How does one look at hundreds of master games a day? IM Jeremy Silman responds to the question, "What kind of study program did you use?":

  I mostly looked at endless master games (while simultaneously eating copious amounts of ice cream), sometimes going over several hundred in a single day (only stopping when I was slaphappy and drooling). Most young players I talk to don’t go over nearly enough master games, but now that databases are available there’s simply no excuse for this.

Does one simply just take in the patterns that the masters play? How can one learn like this?

Wouldn't it be better to look at maybe ten games in a scrupulous manner?

That depends on what you want from the games.

If you are looking for deep human style analysis, it is of course not possible.

If you are interested in shallow computer automated analysis (like lichess evaluation graph), then it’s possible.

If you are interested in opening theories, it’s possible again. For example, a French player would skip Ruy Lopez games.

Professional players generally don’t study chess games randomly. They would have an objective like rook endgames with two pawns down. Good database search would be useful.

Please define what you want from the games.


Can White win the endgame from game Kramnik-Carlsen, London 2010? [Title "White to move"]
[fen "8/6p1/7p/2k5/8/p5P1/B5P1/6K1 w - - 0 1"]

Can White win this endgame?

According to the analysis of GM Mueller, white is winning.

The game went: 65.Kf2 Kd4 66.Kf3 Kd3 67.g4 Kd2 68.Be6 Kd3.
And now 69.g5! wins in all the lines, while Kramnik played 69.Kg3?, after which the ending is drawn.

The entire game, with the analysis of GM Mueller:

[FEN ""]
[Event "2nd London Chess Classic"]
[Site "London ENG"]
[Date "2010.12.14"]
[Round "6"]
[White "Kramnik, Vladimir"]
[Black "Carlsen, Magnus"]
[Result "1/2-1/2"]
[ECO "D07"]
[WhiteElo "2791"]
[BlackElo "2802"]
[Annotator "Müller,Karsten"]
[PlyCount "171"]
[EventDate "2010.12.06"]
[EventType "tourn"]
[EventRounds "7"]
[EventCountry "ENG"]
[EventCategory "19"]
[StartPly "128"]

1. d4 d5 2. c4 Nc6 3. Nf3 Bg4 4. Nc3 e6 5. Bf4 Bd6 6. Bg3 Nf6 7. e3 O-O 8. a3
Ne7 9. Qb3 b6 10. Ne5 c5 11. Nxg4 Nxg4 12. Rd1 Bxg3 13. hxg3 Nf6 14. cxd5 exd5
15. Be2 Qd6 16. Qc2 h6 17. O-O c4 18. b3 Qxa3 19. bxc4 dxc4 20. Bf3 Rab8 21.
Ra1 Qd6 22. Nb5 Qd7 23. Qxc4 a5 24. e4 Rfc8 25. Qe2 Rc6 26. Rab1 Rd8 27. Rfd1
Rdc8 28. d5 Rc2 29. Qe3 R2c5 30. Nd4 Re8 31. Qd3 Qd6 32. Qa6 Rb8 33. Nb3 Rc2
34. Nd4 Rc5 35. Nb3 Rc2 36. Qd3 Rcc8 37. Nd2 Ng6 38. Be2 Qc5 39. Rb5 Qc3 40. f4
a4 41. e5 Nd7 42. Qxc3 Rxc3 43. Ne4 Rc7 44. Ra1 Ra7 45. d6 Ngf8 46. Nc3 Nc5 47.
Nd5 Ra5 48. Rxb6 Rxb6 49. Nxb6 Nfe6 50. Bc4 Kf8 51. f5 Nd8 52. Rf1 Ncb7 53. Re1
a3 54. e6 fxe6 55. fxe6 Nxd6 56. e7+ Ke8 57. exd8=R+ Kxd8 58. Rd1 Kc7 59. Ba2
Rg5 60. Nd5+ Kc6 61. Nc3 {#} Rc5 62. Rxd6+ Kxd6 63. Ne4+ Kc6 64. Nxc5 Kxc5 {#}
65. Kf2 Kd4 66. Kf3 Kd3 67. g4 Kd2 68. Be6 Kd3 {#} {A miraculous escape. It is
hard to believe that Magnus Carlsen got away with a draw despite being down a
piece.} 69. Kg3 $2 {Kramnik allows the king to penetrate too deeply.} (69. g5 $1 {Hiarcs 13, running on a 12-core machine and providing added information to the live commentary, calmly spat out a mate score with an irreductible winning line.
Here it is with some added analysis to clarify.} hxg5 (69... h5 70.
Kf4 Kd4 71. g3 Kc5 72. Kf5 Kd6 73. Ba2 Ke7 74. Kg6 Kf8 75. Kh7 $18) 70. g3 {
opening the gates to the deadly endgame weapon: the Zugzwang, which takes the
day once more.} Kd4 71. Kg4 Ke3 72. Kxg5 {#and here all attempts to defeat the
triangulation with the bishop will fail.} Kf3 (72... Kf2 73. Kf4 Kg2 74. g4 Kh3
75. g5+ Kh4 76. Kf5 Kh3 (76... Kh5 77. Bf7+ Kh4 78. Ba2 Kh5 79. Be6 Kh4 80. Kg6
) 77. Bb3 Kh4 78. Ba2 Kh5 79. Be6 Kh4 80. Kg6) 73. Kh4 g6 74. Bf7 g5+ 75. Kh3
Kf2 76. Kg4 Kg2 {and now a triangulation with the bishop wins it.} 77. Ba2 Kf2
78. Bd5 $18) 69... Ke3 70. Kh4 (70. g5 {is no longer good enough. Ex:} Ke4 (
70... Kd4 $2 71. Kf4 hxg5+ 72. Kxg5 Ke3 73. Kf5 Kf2 74. g4 Kg3 75. g5 Kh4 76.
Kg6 $18) (70... h5 $2 71. Kh4 g6 72. g4 hxg4 73. Kxg4 Ke4 74. Ba2 Ke5 75. Bf7
$18) (70... hxg5 $2 71. Kg4 Kf2 72. g3 Kg2 73. Ba2 Kf2 74. Bd5 Ke3 75. Kxg5 Kd4
76. Ba2 Ke4 77. Kg4 Ke3 78. Bb1 Kf2 79. Kf4 Kg2 80. Ba2 Kf2 81. g4 Kg2 82. g5
Kh3 83. Kf5 Kh4 84. Bb3 Kh5 85. Be6 Kh4 86. Kg6 $18) 71. Kg4 Ke5 72. Ba2 Ke4
73. g3 Ke3 74. Bb1 Kf2 75. g6 h5+ 76. Kxh5 Ke3 77. Kg5 Kd4 78. Kf5 Kd5 79. Ba2+
Kd6 {and Black has succeeded in securing the draw.}) 70... Kf2 71. Bd5 (71. Kh5
{fails because the white bishop is overwhelmed after} Kxg2 72. Kg6 Kg3 73. Kxg7
a2 74. Bxa2 Kxg4 75. Kxh6 $11) 71... g6 72. Kh3 g5 $1 $11 {White cannot leave
the kingside without losing the g4 pawn.} 73. Kh2 Kf1 74. Be6 Kf2 75. Bc4 Ke3
76. Kg3 Kd4 77. Be6 Ke3 78. Kh2 Kf2 79. Bc4 Ke3 80. Kg1 Kf4 81. Be6 Ke5 82. Bb3
Kf4 83. Be6 Ke5 84. Bb3 Kf4 85. Be6 Ke5 86. Bb3 1/2-1/2


3...c5 in the Advance Caro-Kann Consider the following side line of the Advance Caro-Kann:
[FEN ""]
1.e4 c6 2.d4 d5 3.e5 c5 4.dxc5 e6 5.a3 Bxc5

In master OTB games, the move 3...c5 is one third as common as the main move ...Bf5. The main justification I have heard for this is that black is immediately conceding to a lost tempo by having first played first ...c6 and only then playing ...c5. I contend that this justification makes no sense, for two reasons:
(1) In the main line after 3...c5, black immediately regains the tempo when he recaptures with the bishop on c5. True, white can himself gain a tempo on the bishop with b4, but it is at least questionable whether this is the best move in the position.
(2) Even if we grant that black doesn't really regain the tempo because the bishop will have to move again, the fact remains that in the lines after ...Bf5, black still needs to play ...c5 at some point. But whenever he plays it, he will still be losing a tempo. Where is the harm losing this tempo on move three rather than on some later move?
So my question is: is the 'lost tempo' really the reason why 3...Bf5 is preferred to 3...c5?

I believe 3...Bf5 is preferred is because they want to play a Caro-Kann and not the French defense.  Black's main problem with his position after 4...e6 is the Bishop on c8.  White still has all his pieces on the first rank while Black has a Bishop developed so any loss of tempo is not really an issue here.