How close was Seirawan to challenging Kasparov? Growing up in the '80's in the Pacific Northwest (USA), my chess hero naturally was Yasser Seirawan.  He was the first top-class GM to emerge from the USA since Fischer and our country's best hope to break the Soviet headlock on world chess.  Our hopes at the time seemed reasonable - he twice made the Candidates Matches.  Sadly, after the fall of the Iron Curtain the chess world fell into general chaos, and my understanding is that Yasser spent what should have been his peak competitive years focused on simply making a living in a difficult chess economy.  He famously beat the newly minted world champion, Kasparov, in the '86 Olympiad, but never had a chance at the title.  He semi-retired from competitive chess around the turn of the century, but has returned to competition on occasion and turned in some very strong results.  In 2011 he earned a silver medal in the World Team Championships, representing the USA, with a 2773 performance rating.  (To me, that seems a ridiculous result!)

My question to the historians of the game:  Did Seirawan have the potential to challenge Kasparov, but was held back by his inability to focus entirely on chess in that chaotic era?  Or am I just making excuses for my hero, and I should be content with Seirawan's considerable achievements and the salutary impact that he has had on American (and world-wide) chess.

There are games on record between the two:

[Title "Yasser Seirawan vs Garry Kasparov (1986)"]
[Event "Dubai"]
[Site "Dubai"]
[Date "1986.11.23"]
[EventDate "?"]
[Round "8"]
[Result "1-0"]
[White "Yasser Seirawan"]
[Black "Garry Kasparov"]
[ECO "D91"]
[PlyCount "123"]
[FEN ""]

1.d4 Nf6 2.c4 g6 3.Nc3 d5 4.Nf3 Bg7 5.Bg5 Ne4 6.cxd5 Nxg5
7.Nxg5 e6 8.Nf3 exd5 9.b4 Qd6 10.a3 O-O 11.e3 c6 12.Be2 Bf5
13.O-O Nd7 14.Na4 a5 15.Qb3 b5 16.Nc5 a4 17.Qc3 Nb6 18.Nd2
Rae8 19.Rfe1 Re7 20.Bf3 Rfe8 21.g3 Bh3 22.Bg2 Bxg2 23.Kxg2 f5
24.h4 Nc4 25.Nf3 Bf6 26.Re2 Rg7 27.Rh1 Qe7 28.Ree1 h6 29.Qd3
Rf8 30.Nd2 Qe8 31.Nxc4 dxc4 32.Qd1 Re7 33.Ref1 Qf7 34.Qf3 Qd5
35.Qxd5+ cxd5 36.Kf3 Bg7 37.Rd1 Rff7 38.Rd2 Re8 39.Rdd1 Bf8
40.Rdg1 Bg7 41.Rd1 Kf8 42.Rd2 Ke7 43.Rdd1 Kd6 44.Rh2 Kc6
45.Rhh1 Bf8 46.Rd2 Bd6 47.Rdd1 Bxc5 48.dxc5 Re4 49.Rhe1 Rd7
50.Rd4 g5 51.hxg5 hxg5 52.Red1 Rxd4 53.Rxd4 Rh7 54.Ke2 Rh3
55.g4 f4 56.exf4 Rxa3 57.fxg5 Ra2+ 58.Kf3 c3 59.Rd1 d4 60.g6
d3 61.Ke3 Rxf2 62.g7 1-0

[Title "Garry Kasparov vs Yasser Seirawan (1988): You Come at the King, You Best Not Miss"]
[Event "Thessaloniki ol (09)"]
[Site "Thessaloniki GRE"]
[Date "1988.11.22"]
[EventDate "?"]
[Round "9"]
[Result "1-0"]
[White "Garry Kasparov"]
[Black "Yasser Seirawan"]
[ECO "D21"]
[PlyCount "76"]
[FEN ""]

1.d4 d5 2.Nf3 c5 3.c4 dxc4 4.Nc3 cxd4 5.Qxd4 Qxd4 6.Nxd4 Bd7
7.Ndb5 Na6 8.e4 Nf6 9.f3 Bxb5 10.Nxb5 e5 11.Be3 Bb4+ 12.Kf2
Ke7 13.Bxc4 Rhc8 14.Rac1 Bc5 15.Rhd1 Bxe3+ 16.Kxe3 Ne8 17.Bb3
Rxc1 18.Rxc1 f6 19.a3 Nd6 20.Bd5 Nxb5 21.Bxb7 Nbc7 22.Bxa8
Nxa8 23.Rc8 Nb6 24.Rg8 Kf7 25.Rh8 Nc5 26.Rb8 Ke7 27.b4 Nc4+
28.Ke2 Nd7 29.Rg8 g5 30.a4 a5 31.bxa5 Nxa5 32.Ra8 Nc6 33.a5
Kd6 34.g3 h5 35.h4 gxh4 36.gxh4 Nc5 37.a6 Kc7 38.a7 Nb7 1-0

[Title "Cup World: Seirawan vs Kasparov (1989)"]
[Event "Cup World"]
[Site "Skelleftea SWE"]
[Date "1989.08.??"]
[EventDate "?"]
[Round "13"]
[Result "1/2-1/2"]
[White "Yasser Seirawan"]
[Black "Garry Kasparov"]
[ECO "E75"]
[PlyCount "85"]
[FEN ""]

1.d4 Nf6 2.c4 g6 3.Nc3 Bg7 4.e4 d6 5.Be2 O-O 6.Bg5 c5 7.d5 h6
8.Be3 e6 9.Qd2 exd5 10.cxd5 Re8 11.f3 h5 12.a4 a6 13.a5 Nh7
14.Bd1 Nd7 15.Nge2 Ne5 16.b3 Qh4+ 17.Bf2 Qf6 18.Qe3 h4 19.h3
g5 20.O-O Bd7 21.Kh1 Nf8 22.Bg1 Nfg6 23.Bh2 c4 24.Rb1 Rac8
25.Qa7 Nf4 26.bxc4 Nxc4 27.Rxb7 Nd2 28.Rg1 Nxh3 29.e5 Rxe5
30.Rxd7 Nxg1 31.Qxg1 Ree8 32.Rxd6 Qf5 33.Ba4 Qd3 34.Bxe8 Rxe8
35.Rc6 h3 36.Bg3 hxg2 37.Qxg2 Nxf3 38.d6 Re6 39.Qf2 g4 40.Rc8+
Kh7 41.Nf4 Rh6+ 42.Kg2 Ne1+ 43.Kg1 1/2-1/2

Yasser Seirawan won the World Junior Chess Championship in 1979 in Skien Norway, a year before Garry Kasparov won it in Dortmund Germany. The two were contemporaneous. Seirawan proceeded to train in Switzerland with Korchnoi following his Junior Chess Championship win.

It's not precisely clear why the two didn't meet up in international competition. In the games they played it seems Seirawan was competitive against Kasparov.

In interview's Seirawan stated publicly that he doesn't like the FIDE cycle at all and that he always enjoyed being busy and working on projects (such as writing). Speculating, it could be Seirawan's dedication to editing Inside Chess magazine and his dislike for the FIDE cycle may have distracted him away from international competition.

Perhaps only Seirawan knows.


A cramped opposite color Bishop endgame From "Modern Endgame Manual" by Mikhalchishin, the following position is analysed and determine to be a winning position for White.
Is Mikhalchishin's analysis correct or does the defensive capabilities of modern engines make this a position a draw?
[Event "Russian Championship Higher League"]
[Date "2013.06.23"]
[White "Boris Grachev"]
[Black "Daniil Dubov"]
[Result "1-0"]
[ECO "D47"]
[WhiteElo "2683"]
[BlackElo "2638"]
[FEN "1b4k1/p4p1p/5p2/2P1pB2/8/8/P4PPP/5K2 w - - 0 33"]
[EventDate "2013.06.19"]

The analysis of this position seems quite reasonable based off an immediate glance of the board. Grachev has the advantageous position as he is first to move in this position which is essential for this end game play out. The c5 pawn is key to Grachevs success and without playing out the whole game immediately moving to defend it with the King is the most route to success. Dubov is incapable of promoting on the King side of the board and the double pawns do provide somewhat of a hinderance to Dubovs position.
This is effectively how the game rolled out to my understanding of it, Grachevs king charged at the c5 pawn, Dubovs and Grachevs Bishops began gobbling up pawns and White ultimately used the king to progress the queen side pawns on the A and C file to the point Dubov resigned.
In regards to the definitively analysing with modern engines. Using Komodo Dragon against itself for 10 games, in all 10 games White won. In this position, white is better in all key lines ranking from +3.53 (in the best line for White) to +1.4 in the worst line.


Can a chess book (or ebook) have too many diagrams? It is considered that diagrams make chess books easier to read, but there are obvious space limitations to how many of them can be included - mostly in printed books. An ebook has less of a concern for maximum number of pages, but is it still possible to make readability worse by having diagrams sprinkled too frequently in the notation?

Let's start by saying that that's a subjective question. What is "too many" for one person may be just right for another.

That being said, let's take a ridiculous case: A diagram for every move, whether main line or variation. The diagrams would get in the way of the exposition. It's safe to say that very few chess players would benefit from such a book.

The "most friendly" chess books I have read include diagrams every 6-10 moves of the main line only, whether with or without exposition. There is a reason behind this. Buffering and Human Memory describes this phenomenon, with a full paper called The Magical Number 7. Briefly, humans can remember 7+/-2 discrete items without having to switch knowledge in and out of "storage".

This will also arrange matters such that a reader can follow the play without a board, but make it desirable nonetheless that a board be used. In addition, if the reader makes an error in replaying moves, 6-10 move intervals make reasonable "checkpoints" to return to.


Why do we increase depth of search for a mate detection in alpha beta pruning? I was following a tutorial for making a chess engine and in that, while writing the alpha beta pruning function the tutorial before checking for all possible moves generated , checks weather the current side is in check or not. If in check the depth was increased and i couldn't understand the reason. I am fairly new to chess engine programming and have searched about this but couldn't find anything relevant.
Any help will be much appreciated.Thanks.

Here is the code for alpha beta pruning.

function AlphaBeta(depth, alpha, beta)
{
    SearchController.nodes++;
    if (depth <= 0)
    {
        return Evaluate();
    }

    //fiftyMove rule or if a position is Repeated
    if ((IsRepeated() || GameBoard.fiftyMove >= 100) && GameBoard.hisPly != 0)
        return 0;

    if (GameBoard.ply > MAXDEPTH - 1 )
        return Evaluate();

    //this is the line i am talking about
    var InCheck = SqAttacked(GameBoard.pieceList[Kings[GameBoard.side] * 10] , GameBoard.side ^ 1 );
    if (InCheck)  {
        depth++; //<---------HERE
    }

    var score = -INFINITE;

    GenerateMoves();

    var Move = NOMOVE, MoveNum = 0, BestMove = NOMOVE;
    var legal = 0; // To see weather any legal moves are possible
    var start = GameBoard.moveListStart[GameBoard.ply], end = GameBoard.moveListStart[GameBoard.ply + 1];

    for(MoveNum = start; MoveNum < end; MoveNum++)
    {
        Move = GameBoard.moveList[MoveNum];

        if (!MakeMove(Move))
            continue;

        legal++;

        score = -AlphaBeta(depth - 1, -beta, -alpha);

        TakeMoveBack();

        if (score > alpha)
        {
            if(score >= beta)
                return beta;

            alpha = score;
            BestMove = Move;
        }

        console.log('For move : ' + PrMove(Move) + ' Score : ' + score );
    }

    if (BestMove != NOMOVE)
    {
        StorePvMove(BestMove);
    }

    if (legal == 0)
    {
        if (SqAttacked(GameBoard.pieceList[Kings[GameBoard.side] * 10] , GameBoard.side ^ 1))
        {
            return MATE - GameBoard.ply;
        }
        else return 0;
    }

    console.log("");
    console.log("Best Move at Height : " + depth + ' Move : ' + PrMove(BestMove) + ' Score : ' + alpha);
    return alpha;

}

I can see more than one reason for that.

One reason is that after a check there are very few moves available: usually there are 30 moves available, but after a check there are usually at most 4 or 5. So that move doesn't count as a full ply if you want to measure the size of the resulting tree, and in the same search time you can go deeper.

Another reason, and I think it is the most important, is that a check is a forcing move, and consequences of a forcing move must be considered more deeply. So it is good to go deeper after a check.

Note that in this way, the program will tend to analyze all forced sequences of consecutive checks very deep, in this way it can easily find all perpetual checks and many forced mates. So this is can be very useful.


Are there any rules for transgender players in chess? Wikipedia's article on transgender people in sports indicates there's considerable controversy about male-to-female players competing in women's competitions. The controversy is over physical prowess that's retained through the sex change process. For this, chess is special, because physical prowess presumably matters less in chess. Further, it's already possible for women to join open tournaments and play against men.

I'm wondering if there're any rules concerning transgender people in chess. For example:

If Carlsen (as of time of writing the [male] World Chess Champion) decides to sex change, are there rules that bar him (her?) from competing in Women-only competitions?
If Carlsen decides to sex change, does he instantly become the Women's World Chess Champion?
If Carlsen decides to sex change, does he instantly acquire the WGM title?

I'm wondering if there're any rules concerning transgender people in
  chess.

I asked this question or something very like it of someone who was in a position to know. Basically if your sex is recorded by FIDE as "M" and you tell them it has changed to "F" (actually your federation has to tell FIDE. Not you since FIDE trust the federations who they know rather than the players who they generally don't know) then FIDE will change your records to reflect this fact. Similarly if you choose to go in the opposite direction. I should add that I asked this question in a spirit of intellectual curiosity rather than personal interest :-).

  If Carlsen (as of time of writing the [male] World Chess Champion)
  decides to sex change, are there rules that bar him (her?) from
  competing in Women-only competitions?

First you should know that there is no such thing as "male" World Champion. Carlsen is world champion, period. If one of the top women players qualifies to play him (or another person) for the title of "World Champion" and wins then that woman would become World Champion.

If Carlsen decides to change sex then she would, of course, be eligible to play in Women-only competitions.

  If Carlsen decides to sex change, does he instantly become the Women's
  World Chess Champion?

Your question is grammatically wrong. It should read "does she instantly become the Women's World Chess Champion?"

The answer is, of course, "obviously not". There is a cycle of tournaments which anybody wanting to become Women's World Chess Champion must compete in and succeed in to become Women's World Chess Champion. Carlsen would have to do this first.

  If Carlsen decides to sex change, does he instantly acquire the WGM
  title?

Again the grammatical error in the question. It should be "If Carlsen decides to sex change, does she instantly acquire the WGM title?"

Certainly not! She would have to apply for the title. FIDE would have to decide if norms achieved while a man qualify for women's titles. I would suspect not which would mean that she would have to achieve the norms required as a woman.

I would add one further point. In general titles cost money. FIDE charges you if you want a title and have qualified for it. In your hypothetical situation if Carlsen wanted even the WFM title, even the WCM title, then she would have to apply and pay for the title.

I know the new regime under Dvorkovitch has talked about charging players and officials (arbiters and organizers) less and getting more money from sponsorship but I don't think this rhetoric has been changed into action yet.


Python-chess : how to get a list for the best engine moves I am working on a simple cheat detection script to find if a user used one of the  top engine moves in a game, so I found this great python-chess library
Additionally, I found this example to getting the moves score. But that topic is an old version of the lib so I tried to update the script. However, I keep getting errors, and I don't know how to get the scores in the right way.

import asyncio
import chess
#import chess.uci
import chess.engine
import chess.pgn
import io
#Let's try our code with the starting position of chess:

fen = 'rnbqkbnr/pppppppp/8/8/8/8/PPPPPPPP/RNBQKBNR w KQkq - 0 1'
board = chess.Board(fen)

#Now make sure you give the correct location for your stockfish engine file
#...in the line follows: e.g., /home/.../stockfish_6_x64

engine = chess.engine.SimpleEngine.popen_uci('/home/shar/Desktop/cheat detect python/stockfish-10-linux/Linux/stockfish_10_x64')

if board.turn: print( 'White to move');
else: print( 'black to move');

for el in board.legal_moves:

    pgn = io.StringIO(board.san(el))

    thnwpgntofen = chess.pgn.read_game(pgn);
    nwinfo = engine.analysis(thnwpgntofen.board());

    print(nwinfo["score"])

    print("-------------------------");

I get this error after running my code:

  Traceback (most recent call last):   File "prntengmv.py", line 37, in

      print(nwinfo["score"]) TypeError: 'SimpleAnalysisResult' object is not subscriptable

As per: https://python-chess.readthedocs.io/en/latest/engine.html#indefinite-or-infinite-analysis

engine.analysis(board) now returns an AnalysisResult object, which has the property info that you want.

So instead of:

nwinfo = engine.analysis(...)
print(nwinfo["score"])

You would loop over info in the AnalysisResult, and print the score property from each element:

with engine.analysis(...) as analysis:
    for info in analysis:
        print(info.get("score"))

However, your use case looks like it may benefit from engine.analyse more than engine.analysis.


Would bishops be stronger or weaker on the same coloured squares? Assuming one or both players makes a mistake and transposes a bishop and the adjacent knight when setting up the board, would this help or hinder them?
The answers to this similar question suggest it's a disadvantage. However using the lichess board editor for different variations of this (one vs both sides with both on light squared or dark squares, etc) generally shows a larger starting advantage for white for all variations in the stockfish evaluation (up to +0.8 for white having 2 dark-squared and black 2 light-squared, and +0.2 for black being normal but white having 2 dark-squared compared to +0.1 for the standard start), but I'm not sure how valid this analysis is for an alternate starting position.

And the correct answer, as always, is: "it depends on the position" :-)
OK, assume that you start with Bb1/Nc1. Lichess says +0.1. But this is the sum of...

the N generally standing a bit ugly on c1/f1, from my positional feeling
the B doing some concrete attacking (Stockfish unsubtly starts with c3)
other random concrete aspects
the question you asked: What is the isolated effect?

The isolated effect, of course, is that you are a whole piece up on all white squares, but down on black squares. GM Bangiev would rejoice: Adapt your strategy to be playing your dominance on white. (If that is possible.) For example, Bc4+Ng5 against short castling is completely useless. Fire it up with an additional Bb3 and Black already has a big problem.
Remember that different-colored bishops tend to be an advantage for the attacker, who exactly enacts the strategy I just described. (As the dude with the pair I of course would try the exactly opposite strategy - trying to get a position where both of your bishop just stare at pawns posteriors.)


Is Chaturanga/Shatranj an early form of chess or is this altogether different? I had heard from someone that Chess evolved from Chaturanga then Shatranj.  Are there any pointers towards this?

I would like to know counter arguments as well, if any.

Those two games are indeed early forms of chess. The pieces were similar, although their moves were different, and there were some chess rules that had not yet been invented; however, chess evolved from those early games.


How useful is Chess.com Chess Mentor? So I've used the Chess Mentor feature on Chess.com, and completed all of the free courses, and am now using it at 1 lesson a day(extremely slow).

So, I've been considering buying a membership, namely a Diamond one. How useful is the Chess Mentor when considering non-private coaching? By that I mean a class with about 15-20 people taught by a 2000 rated player (Don't have many good players in my country). Would it give a noticeable increase in performance, or would it be just a slight improvement?

I personally don't benefit much from the mentor. However, that is just a preference in learning styles.

However, I still highly recommend a diamond membership for the tactics trainer and videos, as a good, organized at of videos with tactics will make your rating skyrocket!

I suggest Colle-Zuckertort/London systems and Dutch stonewall.


What is the idea behind the touch move rule? Where did this rule originate? Why does it exist?

I just recently learned about it, and in my casual coffeeshop chess games, it has never been mentioned or enforced.

If you're allowed to touch a piece, you can also pick it up and land it on another square, look how the new position would look like, and return it to it's original square if you don't like the new position. Repeat this over and over again, and it becomes very annoying for your opponent.

This explains why the rule might exist, but not since when. I do not know the answer to that question.


Have there been any simul round-robin games? It occurred to me that it would be possible to have a match in which, say, each of 10 players play each other simultaneously twice. That is, if a regular simul match is a line of boards, this would be a grid, with each player playing black along one row, and white along a column. (The intersection of their row and column would obviously not be played...) Doing it online would simplify things a lot.

It seems like it would be a pretty interesting test of abilities, and solve the usual one-sided nature of simul matches.

Has this been done? What's the common term for it?

Although I've never seen such a simul in action, I've heard of a similar concept before. The person who explained it to me called it something like "walking clock simul", but I doubt if there is an official name.
He applied it to a single round-robin (instead of a double round-robin) and a line of boards (instead of a grid), but the idea remains the same.

In any case, for N players, the number of required boards is N*(N-1)/2 for a single round-robin or N*(N-1) for a double round-robin.

For 4 players (A, B, C, D), the pairings of a single round-robin could look like this:

A - B
C - D
D - A
B - C
D - B
A - C

In his format, the players would walk in the same direction (for instance clockwise) around the boards.

By the way, it is also possible to apply the idea to Swiss tournaments. For N players and M rounds, the number of necessary boards is M*N/2. Note that a single round-robin can be seen as a Swiss tournament with M = N-1.


What is 'Depth' in Lichess game analysis? I have started analyzing my games in Lichess. I'm wondering what does Depth mean in the Stockfish analysis?

It means how many half moves ahead stockfish looked from the current position. It doesn't mean it looked at all the moves possible to that extent thought, it trims what it analises, otherwise it would be unable to reach such depths, this means a mate in 10 for example may only be found when stockfish searches in greater depths. In general, greater depths mean better analysis and moves suggested by stockfish. The only limiting factor is time and processing power.


Is this an example of a backwards pawn? e4 e5
d3

At this point, if d3 advances, say at 3. d4 it does not control d4, it is controlled by a sentry (an enemy pawn controlling d4) and is adjacent and behind a same colored pawn at e4.

Is the d3 pawn backwards? I was told no, because it is supported by c2, but Wikpedia's definition of a backwards pawn doesn't care about a backward's pawn's support, only the support it has moving forward.

Thank you.

The pawn on d3 is not backwards since (as you say) it is protected by another pawn.

There must be something missing from Wikipedia's definition. Later on the article (http://en.wikipedia.org/wiki/Backward_pawn) contradicts itself.

  Also, the opponent can place a piece, usually a knight, on the hole in front of the pawn without any risk of a pawn driving it away.

In your example, if black puts a knight on d4, the pawn move c3will drive it away.


Looking for a Horowitz game I just remembered a puzzle from a Horowitz game in which he played white against an Italian (I believe) player whose name started with "M".

The black queen was defending f6, preventing Bxf6#. There was also a pawn about to promote on d7, and a rook stopping it on d8.

How can I find the game in which the position occurred? I can't recall Black player's name.

Could it be Horowitz vs. NN (1939).  (I realize "NN" doesn't start with an M, and may or may not be Italian, and the pawn isn't on d7... but memory can be a funny thing.)

This might be the position you're remembering:

rnb1qrk1/pppp1ppp/5B2/b2BP2Q/8/2P5/P4PPP/RN3RK1 b - - 2 13

I found this by putting in Horowitz playing as White in chessgames.com, then just sort of went through games in a pseudo-random order (start with "M", hit anything remotely Italian, guess at others) until I found a likely candidate.


How to counter 3. Nf3 f5 in the King's Gambit Declined I've read about many of the basic variations of the KGD, e.g. these but none of of them mention the following from Black. This suggests to me that this move may be a mistake from black that I could take advantage of, but I see nowhere good for white to go from here.

What should white play next?

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

1. e4 e5 2.f4 d6 3. Nf3 f5

3...f5 is not a very good move, but it's not a terrible one; there's no immediate refutation. White's best response (verified with the chess program Houdini) is probably to deal with the pressure on his e-pawn by playing 4.exf5 Bxf5 (4.d3 would be passive; 4.Nc3 fxe4 5.Nxe4 d5 gives Black a nice center), then continue to develop, say with 5.Nc3 (covering e4 so that fxe5 is a real threat; if 5.fxe5 dxe5 6.Nxe5 now then 6...Qh4+ 7.g3 Qe4+ double-attacking the knight and rook). White's position is more pleasant but Black is certainly not lost.


What's the difference between a tempo and a tempi? At the start, how many tempo/tempi is White up? On average, how many tempo/tempi is one Pawn worth? What's the difference between a tempo and a tempi?
At the start, how many tempo/tempi is White up? Half, one, or two?
At the start of the game (before White has even made his first move), how many tempi is one Pawn worth?** (For players rated near ~2200 Elo.)

What's the difference between a tempo and a tempi?

Tempi is the plural of tempo.

  At the start, how many tempo/tempi is White up? Half, one, or two?

At the start, White is not up any tempo. There is no such thing as a half tempo, because tempo refers to a single move from one side.

  On average, how many tempo/tempi is one Pawn worth?

This is hard to say. In open positions, often even 1 or 2 tempi might be enough compensation for a pawn and 3 to 4 tempi may make one's position better. In closed positions, tempi don't matter that much, so in those situations 3 to 4 or more tempi might compensate for the loss of a pawn.

I'll give an example-

Consider this opening -

     [Event "2 Tempi gained by White"]
     [FEN ""]

     1. e4 c6 2. d4 d5 3. Nc3 dxe4 4. Nxe4 Bf5 5. Bd3 Qxd4 6. Nf3 Qd8

If you compare the position after Black's 4th move and Black's 6th move, Black hasn't changed its position; white has developed two extra pieces (2 tempi) and it's White's turn to move. However, White lost a pawn in the process.

I analyzed this position with Houdini 1.5 at depth 20 and here's the assessment -

After Black's 4th move -

= (0.28): 5.Ng3 Bg6 6.Be2 e6 7.Nf3 Nd7 8.0-0 Bd6 9.c4 Ngf6...

After Black's 6th move -

= (0.06): 7.Qe2 Nf6 8.0-0 Bxe4 9.Bxe4 Qc7 10.Rd1 Nbd7...

So, as per Houdini's evaluation White's two tempi was not sufficient compensation for the lost pawn (because the score reduced from 0.28 to 0.06.

Now, suppose I give White an extra tempi, so that the following position is reached with White to play -

 [FEN "rn1qkbnr/pp2pppp/2p5/5b2/4N3/3B1N2/PPP2PPP/R1BQ1RK1 w kq - 0 7"]
 [Event "3 Tempi for White"]

Here, Houdini's evaluation at depth 20 is

 +/= (0.54): 7.Qe2 Bxe4 8.Bxe4 Nd7 9.Bf4 e6 10.Rfd1 Ngf6 11.Ne5 Qb6...

So, Houdini thinks White is better with the 3 gained tempi after the loss of the pawn.

Of course, this is just computer evaluation. From a human perspective, we can say that 3 of White's pieces are already developed and White is castled. Black has only one developed piece. None of it's kingside pieces have moved, so Black's king will be in the center for a while. White's rooks will quickly occupy the open files, so White will develop enough pressure. Thus, White is slightly better.

In open positions, my judgment (subjective, of course) is that a pawn is worth somewhere between 2-3 tempi, whereas in closed positions, it may be worth between 3-4 tempi (if the side with the tempi uses the tempi to open up the position or gain a similar advantage). Thus on an "average", a pawn is worth 3 tempi.


Is it rude to ask my opponent to resign an online game when they have a lost endgame? I really don't know if I am correct when I ask my opponent to resign when I am at a 1800-1900 ELO level. I have an Asperger disorder. To me ,endgames are more clear to play than middlegames, and the game loses interest when I think a newbie would win it. I sometimes ask my opponent to resign and play a rematch. Sometimes it has an effect, and they resign. At other times, I feel myself uncouth.

[fen "5k2/1p6/p3pP2/P1p1K2p/2P4P/8/5Bp1/8 w - - 0 1"]

Is it unfair to ask for a resignation in these kinds positions in an online chess game?

Is it rude to ask my opponent to resign an online game when they have
  a lost endgame?

Yes, it is rude, although you are in good company. In one Olympiad Victor Korchnoi is alleged to have asked his opponent - "Do you speak English?" When they said "Yes" he replied "Then please resign". I may be misquoting. He may not have said "please" :-)

Strictly speaking today what Korchnoi did is not allowed in over the board chess because it is disturbing the opponent. In online chess, however, trash talking is more acceptable because the opponent can always mute by switching off chat.


How do I avoid losing to lower rated players? I'm a Class B chess player. I'm afraid of playing low rated players because if I lose my rating goes drastically down. Sometimes low rated chess players are underrated or they play really good one game against a stronger player.

First, losing is part of chess. If losing didn't suck, then winning wouldn't rock.

Ratings are approximations. Don't let your rating define you.

The way to prevent lower rated players from defeating you is to not allow them to do so. Improve your play such that you can adequately punish the superficial hope-chess moves that "C" players play.

edit - There's no magic wand wand we can wave to help you. There is only working harder so you can play better moves.


How can you castle legally in Chess960 when the castling rook is on the king's destination square? According to the FIDE Laws of Chess:

  4.4 If a player having the move:
  4.4.1 touches his king and a rook he must castle on that side if it is legal to do so
  4.4.2 deliberately touches a rook and then his king he is not allowed to castle on that side on that move and the situation shall
  be governed by Article 4.3.1

Yesterday in the semi-finals of the Chess960 World Championships in the following position Nepomniatchi tried to castle kingside by first picking up his rook to move it off the king's destination square (g1) to f1, the rook's destination square and then moving the king to g1.

The arbiter ruled in accordance with 4.4.2 that he was not allowed to castle kingside and the king must stay on e1 and he got a bad position. Later, after an appeal, this was overruled and they replayed the game.

 [title "Neponiatchi - So, 2019 Chess960 1/2 final"]
 [fen "2nr1r1k/pb1n1pqp/1p2p1p1/1N1pN3/5P2/1P4P1/P2PPQ1P/2R1K1RB w - - 0 1"]

Jonathan Tisdall, on Twitter, reported that:

  According to organizer Jøran Aulin-Jansson, the rook being on g1, the
  king destination, caused enough confusion to overturn the strict
  ruling

This raises the question: In such situations how can the player legally castle on the side where the rook starts on the king's destination square?

One humorous, though impractical at short time limits, solution was suggested here.

Even more impractical was MrDodgy's suggestion:

  A true pro would pick up the rook from g1, toss it up in the air,
  slide the king to g1 and the rook would land dead centre of f1.  Press
  the clock, lean back in chair.  Flex.

Still illegal.

The FIDE Laws of Chess actually cover this with a recommendation without mentioning the problem.

  II.3.2.5.1 When castling on a physical board with a human player, it
  is recommended that the king be moved outside the playing surface next
  to his final position, the rook then be moved from its starting
  position to its final position, and then the king be placed on his
  final square

The first time I read this I though "What a daft thing to suggest? Who is going to do that?" but now I see the point.

The FIDE Laws of Chess go on to state:

  II.3.2.7 Notes
  II.3.2.7.1 To avoid any misunderstanding, it may be useful to state "I am about to
  castle" before castling.

Suppose Nepomniatchi had read that before and said those words before castling, would the arbiter have allowed him to castle the way he did?

So, it looks like this was thought of when the rules were written and they were written accordingly.

For practical play there is a simpler solution. According to 4.4.1 touching the king then the rook must be followed by castling. In cases where either the rook is on the king's square or the king is on the king's square just touch king then rook and then make the move. This solves all the associated problems.


How to efficiently memorize games? I want to memorize some games so that I can replay them in my mind without a board. The reason for this is that I think it could be helpful for improving my strength. I want to be able to fully replay the game, to visualize the pieces in every position, to check variants etc.

Now this is an arduous task (at least for me).

What do you think is the easiest way to accomplish it?

Edit:

This might sound like playing blindfold, but that is not the point of my question. I read about tools for learning playing blindfold, like software to improve visualization-skills or techniques.

I am looking for ideas and hints how I could design the learning process more comfortable when memorizing games – maybe using some kind of software, maybe how to progress when starting to learn a game by heart.

Playing blindfold is not going to be easy, as @Annatar states. Only if you practice much (and accept that you're going to fail the first few times), you will succeed and over time it will probably become easier.

That said, here are some hints:

Start with short games. It's easier to replay a 15 move miniature than a 80 move endgame with lots of rook maneuvers.
Use games from openings you play yourself. If you're not familiar with the Sveshnikov pawn structure or the typical moves of a King's Indian, they'll be harder to remember and to visualize.
Use your own games. Especially the most recent one, which is still 'living' in your memory and you probably have analyzed it already after the game itself. Check if you can still 'reach' that position where that crazy bishop sacrifice was possible which you and your opponent talked about in the post-mortem.


Why are there few or no black super GMs? In the history of FIDE chess competitions or rankings, why hasn't there been a black super GM (2750+ elo)? What could be the hindrance or what is it that the black players are not doing right that other players from other races are doing right in chess?

The number of players was already mentioned. But lets go one level deeper than that.

There are two driving factors in the chance that a player becomes a top player:

Talent
Education

And once you know the chance that someone becomes a top player, you can multiply this with the number of players. Which depends on the population and chance of someone playing.

A very simplistic formula might be:

  Expected number of top players = Population size * likelihood to play
  * likelihood to have enough chess talent * likelihood to have enough chess education

Now, let's look into each of the factors:

Likelihood to have enough chess education

This is both cultural and economical.

Beginner level: The more people play chess, the more likely you have access to someone who can explain you the rules, and teach you how to play

Intermediate level: If more people play, you are more likely to find suitable opponents to develop against. If the local economy is better, it is more likely that you can afford basic training materials or have the chance to play/study online. A combination of economy and player density will determine if you are able to play many tournaments.

Advanced level: At this point training will require a serious investment of time and money that not everyone can make. Logistics are slightly easier if there are several strong tournaments nearby, but you will still expect to travel international. Also don't underestimate the fact that you will likely not be able to work (or at least less) outside chess if you want to climb to the top.

Likelihood to play

Once a sport is popular, it is much more likely to be picked up by new people. A clear example can be found in the Netherlands, where the sport got really booming for decades after Max Euwe became the world champion. Not only will this lead to more players, it will often also lead to more facilitating infrastructure/clubs which may encourage people to play.

Likelihood to have enough chess talent

There are plenty of controversial statements that could be made here, but I think it is fairly safe to say that starting with general education and calculation/reading skills have a positive impact on chess talent coming out.

Population size

More people leads to more potential players.

Conclusion

The reason why there are less Black top players, is because the population in general has a lower average likelihood to become one. For people in less faverable circumstances the answer so far should already explain things clearly. For other people (e.g. those in the US) I think the main reason is that they have a reduced likelihood to become a player. If earlier generations did not play themselves, and there are no past champions to inspire you, that will slow down adoption.

That being said, as education and economical development increases across the globe, I think we just need one black world champion of a few top players in general before we start seeing many black players grow to the top :)


The highest amount of moves by the losing side in a zugzwang In zugzwang, the usual idea is to limit the number of moves that the opponent can make. But they can also have many moves in certain scenarios.
What is the highest amount number of moves by the losing side in a zugzwang position, with and without promoted pieces allowed?

The following are full-point zugzwangs, so both sides are losing if either moved!

[Title "Noam Elkies. EG 128, Apr 1998, p.53, 10967 (v)"]
[StartFlipped "0"]
[fen "8/8/k7/8/K7/RNbn4/B7/1R6 w - - 0 1"]

1. Rc1 Nb2#

White: 8 with wRb1, 6 with N = 14. Black: 11 with B, 8 with N, 3 with K = 22. Total-36.

[Title "Noam Elkies. EG 128, Apr 1998, p.53, 10967 (text, v)"]
[StartFlipped "0"]
[fen "8/8/8/k1n5/8/K7/RRb5/QBb1n3 w - - 0 1"]

1. Bxc2 Nxc2#

White: 1 with B = 1. Black: 9 with Bc2, 6 with Bc1, 8 with Nc5, 3 with Ne1, 1 with K = 27. Total-28.


Queen's Indian Defense question that has me stumped After the moves 1.d4 Nf6 2.c4 e6 if White plays 3.Nf3, Black often plays the Queen's Indian Defense with 3...b6. But if White plays 3.Nc3, then Black rarely plays 3...b6.

 [FEN ""]

  1.d4 Nf6 2.c4 e6 3.Nc3 (3.Nf3 b6) b6!?

Does anyone know why that is? (assuming GM level play)

The simple reason is because 3...b6 doesn't prevent 4.e4! when White immediately grabs the center.

   [FEN ""]

   1. d4 Nf6 2. c4 e6 3. Nc3 b6 4.e4!

The bishop on b7 isn't very effective in the kind of pawn structure that arises after e4. Often, White may play f3, strengthening the e4 point and completely blunting the bishop on b7.

Consider this structure -

   [FEN "4k3/pbpp1ppp/1p2pn2/8/2PPP3/2N2P2/PP4PP/4KB2 w - - 0 1"]
   [Event "Bishop on b7 is blunted by White's pawns on e4 and f3"]

Black may want to break White's center with a move like d5, but that allows White to play e5, driving away the knight on f6 with tempo and also establishing a strong pawn on e5, which may enhance White's attacking prospects on the kingside, as I discussed in point number 4 of this post.

  [FEN "4k3/pbpp1ppp/1p2pn2/8/2PPP3/2N2P2/PP4PP/4KB2 b - - 0 1"]
  [Event "The threat of e5 is always looming after d5"]

  1... d5 2. cxd5 exd5 3. e5

Black may also want to play c5, but in those positions, after a move like d5, the position transposes into Benoni type positions where the bishop is completely misplaced on b7, thus Black loses at least a tempo. Besieds, b6 might also be a waste of time in some Benoni positions.

   [FEN "4k3/pb3ppp/1p1pp3/2pP4/2P1P3/2N2P2/PP4PP/4K3 b - - 0 2"]
   [Event "Unfavorable transposition to a Benoni type position"]

Recommended Games -

The following games in this line are quite instructive -

Harry Nelson Pillsbury vs Heinrich Wolf, 1902 1-0

   [White "Harry Pillsbury"]
   [Black "Heinrich Wolf"]
   [Date "1902"]
   [Result "1-0"]
   [FEN ""]

   1. d4 Nf6 2. c4 e6 3. Nc3 b6 4. e4 Bb7 5. Bd3 d5 6. cxd5 exd5 7. e5 Ne4 8. Nf3 Be7
   9.  O-O O-O 10. Qc2 Nc3 11. Bh7 Kh8 12. bxc3 g6 13. Bg6 fxg6 14. Qg6 Qe8 15. Qh6 Kg8
   16. Ng5 Bg5 17. Qg5 Kf7 18. f4 Ke6 19. f5 Kd7 20. Qg7 Kc8 21. e6 Rg8 22. Qh7 Rh8
   23. Qg6 Ba6 24. Qe8 Re8 25. Re1 Nc6 26. Bg5 Nd8 27. Bd8 Kd8 28. f6 Rh8 29. Re5 c6
   30. Rae1 Rc8 31. Rg5 Bd3 32. Ree5 Rh6 33. Rg8 Kc7 34. Rc8 Kc8 35. e7 Bg6 36. e8=Q 1-0

Efim Geller vs Mark Usachyi, 1957 1-0

   [Event "UKR-ch"]
   [Date "1957"]
   [White "Geller, Efim P"]
   [Black "Usachyi, Mark"]
   [Result "1-0"]
   [FEN ""]

   1. c4 Nf6 2. Nc3 e6 3. d4 b6 4. e4 Bb4 5. Bd3 Bb7 6. f3 O-O 7. Nge2 d5 8. cxd5
   exd5 9. e5 Ne8 10. O-O c5 11. a3 Ba5 12. b4 cxb4 13. Na2 Nc6 14. Rb1 bxa3 15.
   Bxa3 Ne7 16. Ng3 g6 17. Nc1 Bc6 18. Qe2 Ng7 19. f4 Re8 20. f5 Nexf5 21. Bxf5
   gxf5 22. Nb3 Qg5 23. Rf3 Rac8 24. Rbf1 Ba4 25. Nxf5 Rc3 26. Nxg7 Qxg7 27. Nxa5
   Rc2 28. Qxc2 Bxc2 29. Nc6 Qh6 30. Rg3+ Bg6 31. Ne7+ Kh8 32. e6 Rxe7 33. Bxe7
   fxe6 34. Rc3 Be8 35. Rc8 Qe3+ 36. Kh1 Qe2 37. Rxe8+ Kg7 38. Ref8 h5 39. Bd6 h4
   40. Be5+ Kg6 41. h3 a5 42. Rg8+ Kh5 43. Rf7 1-0

Phillip Viner vs Elias Castrillon, 1964 1-0

   [Event "Tel Aviv ol (Men) fin-D"]
   [Site "Tel Aviv"]
   [Date "1964"]
   [Round "5"]
   [White "Viner, Phillip"]
   [Black "Iniguez Castrillon, Elias"]
   [Result "1-0"]
   [FEN ""]

   1. d4 Nf6 2. c4 e6 3. Nc3 b6 4. e4 c5 5. d5 d6 6. Bd3 Nbd7 7. f4 exd5 8. cxd5
   Be7 9. Nf3 O-O 10. O-O a6 11. a4 Bb7 12. Bc4 Qc7 13. Re1 h6 14. e5 Nh7 15. b3
   Rfe8 16. Bb2 Ndf8 17. Qd2 Ng6 18. Rad1 Bf8 19. Ne4 Qd8 20. Nxd6 Bxd6 21. exd6
   Qxd6 22. f5 Nf4 23. Be5 Rxe5 24. Rxe5 g5 25. fxg6 Nxg6 26. Qxh6 Nf6 1-0


Gull engine : Which depth value to set 6 difficulty levels? We are installing the Gull engine for some chess enthusiasts in an organization.
We would like to set 6 difficulty levels from beginner to master using depth.
Is there someone who can advice us about which values are the most accurate and progressive for each level?

You may find this post by the developers of the website https://lichess.org/ helpful.

Although they use Stockfish as the engine, they set the search depths as such (note that they have eight levels of play):

AI level 1: skill 3/20, depth 1, 50ms
AI level 2: skill 6/20, depth 2, 100ms
AI level 3: skill 9/20, depth 3, 150ms
AI level 4: skill 11/20, depth 4, 200ms
AI level 5: skill 14/20, depth 6, 250ms
AI level 6: skill 17/20, depth 8, 300ms
AI level 7: skill 20/20, depth 10, 350ms
AI level 8: skill 20/20, depth 12, 400ms

I have personally played and seen others play against the varying levels. Level 1 is almost joke worthy--the computer may move his queen completely into danger, completely miss checkmates, etc.

On the other hand, level eight is crushing; beating it requires repeated practice over the same line (at least, that is the only way I've seen people beat it).


How bad is the English Opening Wing Gambit? After 1.c4 c5 2.b4 cxb4 it seems White can continue in typical gambit fashion with a number of moves (3.a3, d4, ...) yet I have never seen a game with this gambit.  Did anyone strong ever try this?  Is there a clear refutation?

[fen ""]

1.c4 c5 2.b4 cxb4

According to the Database of 365Chess, the English Wing Gambit has not been tried by a grandmaster in a rated game.

Although there might not be a clear refutation, the gambit seems to be somewhat dubious. Compared with most gambits, white does not obtain a quick development. Compared with the Sicilian Wing Gambit, white acquires less control in the center. Compared with the Benko Gambit, black's central pawns are still flexible (which was already pointed out by Brian Towers).

After 1.c4 c5 2.b4, the most principled reply is to accept the gambit by 2....cxb4. Now, white has two logical continuations: 3.a3 (Benko style) and 3.d4 (trying to occupy the center). Regardless of white's third move, black can play 3....e6 and 4....d5, after which white doesn't have enough compensation.

Instead of accepting the gambit, black is also more than fine after 2....Nf6, as he will regain the pawn after 3.bxc5 e5.

      [StartPly "3"]

      [FEN ""]
      1.c4 c5 2.b4 cxb4 (2...Nf6 3.bxc5 e5) 3.d4 (3.a3 e6) e6 4.e4 d5


Endgame: Rook + Knight vs Rook What happens in the endgame Rook + Knight vs Rook?  Is it a draw, or can the side with the knight win?  I came across this a few days ago, and I managed to win with the Rook + Knight, but I am not sure if that is just because my opponent made a mistake.

Like its cousin endgame KRBvKR, your ending of KRNvKR is usually drawn. It's not always drawn, of course, but generally speaking KRNvKR is much less dangerous and easier to defend than is KRBvKR. In Secrets of Pawnless Endings, John Nunn writes,

  If the defending king is not in a corner there are a few situations when the rook and knight can win tactically within a few moves, usually by a combination of skewer and knight fork, but in general the rook and knight only have winning chances when the defender's king is very badly placed.

The positions of KRNvKR are a part of existing tablebases, so we can be precise about how often it's a win: 35.9% of positions in which the strong side has the move are winning (see e.g. Ken Thompson's "Retrograde analysis of certain endgames" from 1986). Note that since that says that giving the strong side the move (which is advantageous most of the time) in a random position yields a win only 35.9% of the time, the overall winning percentage for the strong side in KRNvKR is considerably lower than that; I am unable to pin the figure down from any source so far.

For your particular game, Nunn's words can give some inkling as to whether your opponent made a mistake or was already doomed, but if tablebases have taught us anything it's that optimal play can be quite seemingly random, and that heuristics are of limited use for a reliable verdict. If you have a record of the initial KRNvKR position that appeared on the board in your game, though, then a quick Nalimov tablebase query will tell you whether or not your opponent sealed his fate during that ending or before it.


Xboard and a remote engine I want to analyse chess games with xboard and stockfish. Locally this is no problem.
But my PC is slow, so I have rented a faster linux server, and I want let stockfish run on it.
How can I use xboard on my PC, to connect to stockfish running on the linux server?
I have tried on the command line:
1) ssh -p <port> <user>@<host> /usr/games/stockfish

This works. But:
2) xboard -fcp "ssh -p <port> <user>@<host> /usr/games/stockfish" -fUCI

does not work. There is a connection to stockfish on the server, xboard gives the correct version of the engine, but as soon as I enter the first move, it terminates with error of "broken pipe."

You need to connect to your server with ssh -X command to enable X forwarding. The details of how this needs to be configured can be found in this answer on
Unix and Linux Stack Exchange.


Big changes in engine's evaluation after considerable time I hope this question hasn't been asked before.
I am looking for some examples where, say, the latest Stockfish or Komodo engine (or possibly some of the top NN engines) evaluates a position as plus or minus x for some time--possibly oscillating slightly near that point during that period--and then there is a big increase or drop in their evaluation.
What might be a suitable "for some time" period? I want to say more than a minute, but not more than 1 hour. Also, what is a "big" change in evaluation? I am not so sure about that, but let's say something like 3.0.
I am asking this question because, from my (very limited) experience, any dramatic changes in an engine's evaluation occur during the first 20 or so seconds. If an engine cannot find the deep tactics (or the deep positional play) during those first seconds then it is because the search tree has been pruned. (Am I right about this? I don't much about how chess engines operate.)
Edit:
The drastic change in the evaluation should be a consequence of the introduction of a move not previously considered by the engine.

This is a complicated position I had in a correspondence game. White to play and win. The engine evaluation rises and falls, occasionally hitting 0 again. Then it stays at roughly 1.5 for a long while until finally finding the breakthrough about 20 minutes in. Unsurprisingly, considering the full line is pretty insane.
[FEN "r5r1/1np3bk/1p1p4/3P4/bpP2PPp/P3N2P/1q1BQ2K/4R1R1 w - - 0 33"]

1. g5 Rge8 2. Qh5+ Kg8 3. Rg2 bxa3 4. Nf5 Rxe1 5. Bxe1 Bc2 6. Nh6+ Kh8 7. Ng4+ Kg8 8. Nf6+ Kf8 9. Nd7+ Ke7 10. Qg4 Nc5 11. g6 Rh8 12. Re2+ Kd8 13. Nb8 Ba4 14. Nc6+ Bxc6 15. dxc6 Qf6 16. Bf2 Re8 17. Ra2 Qe6 18. Bxh4+ Kc8 19. Re2 Kb8 20. Rxe6 Rxe6 21. Qg2 Re3 22. f5 Be5+ 23. Kg1 Rb3 24. Qa2 Bd4+ 25. Kf1 Rf3+ 26. Kg2 Rb3 27. f6 Rb2+ 28. Kf3 Rxa2 29. g7 Rg2 30. Kxg2 a2 31. g8=Q+ Ka7 32. f7 a1=Q 33. f8=Q Qg1+ 34. Kf3 Qd1+ 35. Kf4 Ne6+ 36. Qxe6 Qf1+ 37. Ke4 Qxf8 38. Qe7 Qxe7+ 39. Bxe7


Are two knights generally worth less than two bishops? A bishop and knight are considered to be about equal in value (three points each). There are even some (closed) positions, where a single knight is worth more than a "bad" bishop, although there are more positions where a bishop is worth a bit more.

But unless they're linked and extremely well placed, (e.g. d4 and e6), two knights are seldom worth more than six points. Some masters put the bishop pair at seven points in an open position because the two bishops together can cover squares of both colors, while moving faster. Does this make two bishops worth more than two knights?

I have read that a fairly open position, two knights may be worth no more than one rook (five points instead of six, or two and a half each). I've never heard this about two bishops. Does this strengthen the case that two knights are worth less than two bishops?

According to GM Larry Kaufman, who has worked on the chess engines Rybka and Komodo, and has done extensive database analysis of material imbalances,

The bishop pair has an average value of half a pawn (more when the opponent has no minor pieces to exchange for one of the bishops), enough to regard it as part of the material evaluation of the position, and enough to overwhelm most positional considerations. Moreover, this substantial bishop pair value holds up in all situations tested, regardless of what else is on the board.

although he goes on to note some exceptions. The whole article is worth reading.


What is the line here? A game I just played at chess.com, in the analysis, it was a missed win at a point. My mind is saturated right now, and I can't think of the line. Can you help me out?

The obvious tactic is

1) ... a6 2) Na3 Nxd4 3) cxN Qxd4 4) QxQ BxQ and you are forking the two rooks on a1 and g1

Disclaimer: I haven't checked this with an engine but it would be my first thought during the game. The engine may find a hole in this


What is the average length of a game of chess? I hope this is an appropriate question for this site as I've been wanting a reputable answer. Of course the length of games can vary wildly, but what is the expected number of moves until either a checkmate or trivial draw position is reached? Preferably the answer will be backed by some evidence and is not just "40 moves" like every other internet source.

EDIT: I opened Mega Database 2012 and found there were 515539 games ranging from the 1400s to 2011. As I couldn't find an efficient way to parse the data, I just used the median move value (I hope it's normally distributed. It's probably not though as the largest number of moves was 277... oh well). The median value was 37 moves, but I'm sure that it's a right-skewed distribution given the max value. If I had to hazard a guess to the average value, I'd put it slightly greater than 40 :)

In addition, keep in mind that these are all recorded games. This means that their origin can be from tournaments, matches, or even online competitions. Indeed, the 277 move game was played in a tournament on the Internet Chess Club.

Oddly enough, I found that the average length of a game (played by humans) is roughly 40 moves. Based on the statistics provided by the Chessgames database (685,801) games, the average number of moves is 40.04. Chessgames tends to only include player games of a high caliber, so this doesn't really take into account amateur tournaments. As these games are played by humans, few of them tend to end in checkmate but rather a draw by mutual agreement or a resignation in a lost position.

This may not be the best source, but I've played in over 320 tournaments in my life and many of these games are imported into my personal database. The average number of moves per game is around 38.

I do not have access to my Mega Database 2012 (a database provided by Chessbase) at the moment, but I will post the average number of moves of approximately 5 million historical games when I open it.


Is this knight sacrifice a good idea? I often play the following variation with black when I play blitz. Somehow it refuses the known lines of the Spanish.
It looks like that black is going to be destroyed but almost always I win when I play this opening.

[FEN ""]

1.e4 e5 2.Nf3 Nc6 3.Bb5 a6 4.Ba4 Nf6 5.O-O b5 6.Bb3 Be7 7.Re1 O-O 8.c3 Nxe4!?

The main idea is that IF white accepts the sacrifice, he/she is going to suffer a pawn storm who will paralyze the queen side.
Almost always (I mean over 95% of the times) the game continuous like this:

  [FEN ""]

1.e4 e5 2.Nf3 Nc6 3.Bb5 a6 4.Ba4 Nf6 5.O-O b5 6.Bb3 Be7 7.Re1 O-O 8.c3 Nxe4!? 9.Rxe4 d5 10.Re1 e4 11.Nd4 Ne5

And after this continuation, black has strong attack.
I really liked the idea that I found something different to play when I am facing the Spanish (By the way, is 8... Nxe4 a "new" idea?), but I think it is possible to get crushed in a game which is not blitz.
So my question is:

  Is 8...Nxe4 a move which gives black something good in general?

The sacrifice is quite dubious.  Besides the answers with 10.Nxe5, 10. Rxe5 is simply two knights for a rook and there is no attack for Black.


Which openings (black/white) should man play against a player, who is not good at endgame but a tactical beast? I'am looking for openings with white and black against strong junior players, which are mostly tactical beasts but not good at endgame.

I typically play double fianchetto (g3,b3 with white and g6,b6 with black); further pawn structure depends on responses; also sometimes playing b4,g4 - but that's more for speed chess; as general idea - some closed position where smart maneuvering matters and no direct encounters in opening if possible - or open 1,2 files and try to exchange few pieces


Could White have won this double rook endgame? I reached this position as white that led to a draw:

[FEN ""]
[White "Bad_Bishop"]
[Black ""]
[StartPly "61"]
[Result "1/2-1/2"]

1. d4 d5 2. c4 dxc4 3. Nf3 Nf6 4. e3 Bg4 5. Bxc4 e6 6. h3 Bh5 7. Nc3 Nbd7 8. O-O Bd6 9. e4 e5 10. g4 Bg6 11. dxe5 Nxe5 12. Nxe5 Bxe5 13. f4 Qd4+ 14. Qxd4 Bxd4+ 15. Kh2 Bxc3 16. bxc3 Bxe4 17. g5 Bd5 18. Re1+ Kf8 19. Bb5 Ne4 20. c4 Nd6 21. cxd5 Nxb5 22. Rb1 a6 23. a4 Nc3 24. Rxb7 Nxd5 25. Re5 c6 26. Bb2 Rd8 27. Rf5 f6 28. gxf6 Nxf6 29. Bxf6 gxf6 30. Rxf6+ Ke8 31. Re6+ Kf8 32. Rxc6 Rg8 33. Rc2 Rg7 34. Rb6 Ra7 35. Rcc6 a5 36. Ra6 Rxa6 37. Rxa6 Rd5 38. Ra7 h5 39. Kg3 Rc5 40. Ra6 Kf7 41. Kh4 Ke7 42. Rh6 Rc4 43. Kg5 Rxa4 44. Rxh5 Ra1 45. Rh7+ Kd6 46. Ra7 a4 47. f5 a3 48. f6 a2 49. f7 Rg1+ 50. Kh6 Rf1 51. Rxa2 Ke6  1/2-1/2

I was up a pawn and had more active rooks. How could white have won this endgame (if there is a win at all)?

48.Kf6 should be winning. After say 48...a2, white goes h4-h5-h6 and something involving ...Rh1, Rxa2 Rxh6+, Kg5 followed by Re2 will lead to the Lucena position.

Much earlier on, I believe 31.Kg3 is winning, but it's also the best try by elimination: without an active king (which is the most important non-trivial factor in rook endgames), white won't be able to win with just his f- and h- pawns vs. black's h-pawn if he loses his a-pawn, and after Rg8 as happened in the game, white's own king is exposed to a perpetual. Black is doomed to passivity because his rooks are disconnected, and white can slowly capture the rest of black's pawns and/or get his king to e6 and promote the f-pawn.

P/S: 17.Re1 Kf8 18.Ba3+ Kg8 19.Rad1 followed by 20.Re7 looks crushing.


What is the “Gufeld Bishop”? I have another question I am going to ask and answer.

The other day, I was watching a chess24 video, and GM Jan Gustafsson mentioned the “Gufeld Bishop”. What is the “Gufeld Bishop”?

Eduard Gufeld was a Ukrainian Grandmaster, who died in 2002. He was a noted expert on the King’s Indian Defense, and wrote two books on it. He won many brilliant games with the KID, and the “Gufeld Bishop” was when the Bg7 came alive, and got great scope, on the a1-h8 diagonal to become a “monster” piece (one that dominated the board, and was hard to oppose)…often on d4.

Here are references to the naming of the Bg7 as the “Gufeld Bishop”.

https://www.theglobeandmail.com/opinion/chess/article756910/

http://www.debestezet.nl/catalog/images/PDF/Art%20of%20the%20kings.pdf

http://seagaard.dk/review/eng/bo_misc/ba_the_search_for_mona_lisa.asp?katid=bo&productid=1..

Now, here are a few games with the “Gufeld Bishop” in action.

In the first, Gufeld, uses a nice tactic to come to d4.

 [Event "Kiev Avantgard-ch"]
 [Site "Kiev"]
 [Date "1960.??.??"]
 [Round "3"]
 [White "Sakhanovich, YV."]
 [Black "Gufeld, Eduard"]
 [Result "0-1"]
 [ECO "E82"]
 [PlyCount "48"]
 [FEN ""]

 1. d4 Nf6 2. c4 g6 3. Nc3 Bg7 4. e4 d6 5. f3 O-O 6. Be3 b6 7. Qd2 c5 8. d5 Re8 9. Bd3 e6 10. Nge2 a6 11. a4 exd5 12. exd5 Nbd7 13. O-O Ne5 14. Ng3 Nxd3 15. Qxd3 Ng4 16. Bf4 (16. fxg4 Rxe3 17. Qxe3 $4 Bd4) 16... Bd4+ 17. Kh1 Nxh2 $1 18. Nge4 (18. Kxh2 Qh4#) 18... Nxf1 19. Rxf1 Qh4+ 20. Bh2 Bf5 21. Qd2 Bxe4 22. Nxe4 Rxe4 23. fxe4 Be5 24. g4 Re8 {And after black trades everything off on h2, Re4 will leave black up two pawns, and more will follow.} 0-1

In the second, the Bishop is unopposed, and when black finally rips open the f-file, it is the straw that breaks the camel’s back.

 [Event "Goodricke op 03rd"]
 [Site "Kolkata"]
 [Date "1992.??.??"]
 [Round "2"]
 [White "Agarwal, Brajesh"]
 [Black "Gufeld, Eduard"]
 [Result "0-1"]
 [ECO "E84"]
 [WhiteElo "2260"]
 [BlackElo "2490"]
 [PlyCount "44"]
 [EventDate "1992.01.??"]
 [EventType "swiss"]
 [EventRounds "11"]
 [EventCountry "IND"]
 [FEN ""]

 1. d4 Nf6 2. c4 g6 3. Nc3 Bg7 4. e4 O-O 5. Be3 d6 6. f3 Nc6 7. Nge2 a6 8. Qd2 Rb8 9. g4 b5 10. Ng3 e5 11. d5 Nd4 12. Bxd4 exd4 13. Nce2 d3 14. Qxd3 bxc4 15. Qd2 Nxg4 16. fxg4 Rxb2 17. Qf4 Rxe2+ 18. Bxe2 Bxa1 19. Bxc4 Bc3+ 20. Kf2 Be5 21. Qf3 Qh4 22. Be2 f5 0-1

And in the last, he used the nice tactic with e4, then maneuver Ba4, pinning the Nb3 to the queen, so he could trade it off, and gain control of d4 again.

 [Event "Tbilisi"]
 [Site "Tbilisi"]
 [Date "1985.??.??"]
 [Round "?"]
 [White "Azmaiparashvili, Zurab"]
 [Black "Gufeld, Eduard"]
 [Result "0-1"]
 [ECO "E94"]
 [WhiteElo "2460"]
 [BlackElo "2470"]
 [PlyCount "72"]
 [EventDate "1985.??.??"]
 [EventType "tourn"]
 [EventRounds "9"]
 [EventCountry "URS"]
 [FEN ""]

 1. d4 Nf6 2. c4 g6 3. Nc3 Bg7 4. e4 d6 5. Be2 O-O 6. Nf3 e5 7. d5 Na6 8. O-O Nc5 9. Qc2 a5 10. Bg5 h6 11. Be3 b6 12. Nd2 Bg4 13. f3 Bd7 14. Rfe1 Nh5 15. g3 f5 16. exf5 gxf5 17. f4 Qe8 18. fxe5 dxe5 19. Bxc5 $6 {Gaining the pawn structure, but poorly judging how strong the Bg7 would become. King safety is always the number one priority in chess.} bxc5 20. Nb3 f4 21. Qd1 Nf6 22. Bd3 Ng4 23. Ne4 Qh5 24. Re2 f3 25. Rf2 Nxf2 26. Nxf2 e4 $1 27. Bxe4 Ba4 $1 {Gaining d4 permanently.} 28. d6 c6 29. Qd2 Bxb3 30. axb3 Bd4 31. Bxc6 Qh3 32. Bd5+ Rf7 33. Bxf3 (33. Bxf7+ $4 Kf8 $1 {And mate on g2 is unavoidable.}) 33... Rxf3 34. Qxd4 Rxg3+ (34...cxd4?? 35. Nxh3) 35. hxg3 Qxg3+ 36. Kh1 Qf3+ (36...cxd4? 37. Rg1 {Black still wins, but has to think about the passers...this is just easier.}) 0-1


Chesss training-Can’t find the proper white move I'm really struggling to find the proper white move. Can someone help me? Also, is there some tool to assist training?

[Title "White to move"]
[fen "2k3rr/pbpp4/1pn1p4/8/2PPB1qp/2N1P2Q/PP4P1/2R2RK1 w - - 0 1"]

The answer is 1.Rf8+, as Cleveland commented. You remove the defender of the queen on g4 (that is, the rook on g8) by distracting it.

[FEN "2k3rr/pbpp4/1pn1p3/8/2PPB1qp/2N1P2Q/PP4P1/2R2RK1 w - - 0 1"]

1.Rf8+ Rxf8 {1...Nd8 2.Qxg4 Rxg4 3.Bxb7+ Kxb7 4.Rxh8} 2.Qxg4

Wins the black queen in exchange for a rook, which means that white is winning. If black doesn't take the rook and instead blocks the check with 1...Nd8, white exchanges queens with 2.Qxg4 Rxg4, then exchanges bishops on b7 with check (3.Bxb7+ Kxb7) because the bishop was attacked twice, and then wins the rook on h8 (4.Rxh8).

As for training tools, workbooks that explain a tactical theme and then give a number of exercises is the usual way, e.g. the Steps Method. A good website like that is Predator at the Chessboard, where a tactic like this could fit in chapter 5.2.


Why is 2...e6 the most common move after 1 d4 Nf6 2 c4, but not after 1 d4 Nf6 2 Nf3? This is the case on the Chesstempo database, and the Chessbase database.

I don't understand why. Wouldn't people who favour Nimzo-type setups play 2...e6 against both moves, and people who favour King's Indian setups play 2...g6 against both? If so, why is 2...g6 more popular than 2...e6 in the position 1 d4 Nf6 2 Nf3?

I believe the reason is that from a theoretical point of view it makes a lot of sense to go for the Queen's Gambit declined, only after white has played Nf3. The most aggressive tries for white in the QGD involve Nge2 and f3, aiming for e4, a plan that was introduced by Botvinnik and is still very dangerous. Obviously this isn't possible if white has already played Nf3.

Also if white goes for d4/c4/Nc3 it makes sense to go for the Nimzo-Indian because the Nimzo is theoretically in excellent shape. Whereas the Queen's Indian at least right now is apparently under some pressure.

I would further argue that the Queen's Indian or the Bogo-Indian aren't closer in terms of "set up" to the Nimzo then the QGD. There is actually a very trendy line right now, that can be reached from both the Nimzo and the QGD: The Ragozin variation.

So this isn't a case of Nimzo-setup against King's Indian-setup, it is just the case that the theoretically soundest repertoire for black against d4 is a combination of Nimzo and QGD. With that in mind the statistics make sense: Basically you go for the QGD whenever Nf3 happens, otherwise you keep the Nimzo option open.


What strategies should I be thinking about at the beginning of the game? In the middle and the end of a chess game, there are visible consequences to almost every move you can make, there are more constraints limiting what is logical to move, and it is fairly straightforward to see what you did wrong when you analyze the game.

At the beginning of the game, it seems like there is a tremendous number of possible ways a game could progress--and not very many of the moves have any immediately tangible consequences. Because of this, I usually have no idea what I should do in the beginning of a game.

Are there any things I should be thinking about at the beginning? Up to date, I've just been moving pieces haphazardly until what I need to do becomes obvious.

There are a few regular things you should fight for out of the opening

Control of the center
Development of pieces
Early castle
Space

So basically you want to get as many pieces out as quickly as possible, while attempting to control the center (the four middle squares and to a lesser extent the next ring of 12 squares). While not all opening strategies revolve strictly around these principles, it is found in the majority of games and especially good rules to play by when starting out.

EDIT: Keep in mind these are not all rigid rules. I would also like to respectfully disagree with Tony. When starting out, memorizing openings is the very last thing you want to do. Feel free to look through an openings book (The first, and very amazing, book on openings that I read) or database. However do not seek just to memorize and spit out moves until you reach a position you haven't actually thought about.


Is there a way to ask stockfish from the command line if a position is "quiet"? Is there a way to ask stockfish from the command line if a position is "quiet"? I am running a script like stockfish_fen.sh to return the analysis, but I would like to also know if stockfish considers this position to be of positional or tactical nature.

I don't think there is anything like that, and it'll never be implemented.

If you insist, you may want to look at how Stockfish does quiescence search. A "tactical" position would mean a dozen of long series of recursive calls. A "quiet" position would mean otherwise. However, this is a very dirty trick which might not work very well, you'd also need to do some programming.

There're other ideas, such as looking at the average branch factor, number of captures in the principal variation, the distribution of the scores... None of which is absolutely satisfactory.


Where can I find this game with a sacrifice followed by a long series of checks leading to a discovered mate? I am looking for a chess game and frankly, I really know very little about it. I remember seeing it somewhere on the Internet.
The game goes something like this. A player (either White or Black) sacrifices their most important piece, probably the queen. This starts a continuous checking sequence. Check is continuously repeated 10-11 times with the opponent's king always having to play a forced move. The opponent's king is forced to move from their rank to the last one. Then the attacking player moves their king to expose the attack of a rook already there, checkmating the opponent.
I know this is near to no information. I have searched the Internet and this site to find this game. But, as I do not have any concrete information, I am not able to find it.
Can you please help me?

I believe that the game you speak of is the extremely famous Lasker-Thomas match in which Lasker forces Black to accept his queen "sacrifice" on move 11. It is followed by a king hunt in which Black's king is forced to the last rank by White, who then finishes the game with the king giving a discovered check from the unmoved a8 rook. The game is notable because White could have chosen the exemplary move 18. 0-0-0#, which is exemplary because castling while also delivering checkmate has been a rare achievement in chess history, but Lasker instead chose the more mundane, in my opinion at the least, 18. Kd2#.
The checking sequence isn't quite 10-11 moves long, but otherwise it fits the bill perfectly, especially with the particular mating move that you described.
[Title "Edward Lasker-George Alan Thomas, London England, 10/29/1912"]
[FEN ""]
[startply "20"]

1. d4 e6 2. Nf3 f5 3. Nc3 Nf6 4. Bg5 Be7 5. Bxf6 Bxf6 6. e4 fxe4 7. Nxe4 b6 8. Ne5 O-O 9. Bd3 Bb7 10. Qh5 Qe7 11. Qxh7+ Kxh7 12. Nxf6+ Kh6 13. Neg4+ Kg5 14. h4+ Kf4 15. g3+ Kf3 16. Be2+ Kg2 17. Rh2+ Kg1 18. Kd2#


Why do engines run faster if you only have one line of analysis open? When I load up an engine (like Stockfish), it reaches a higher depth quicker if I only leave one line of analysis open. If I leave multiple lines open, it runs slower. Why is this?

That's normal, commonly known as multiPV analysis.

Without getting into too much technical details, analysing N number of principal variations require running the engine N times, one for each PV. We need to do that so we can estimate a precise score for each PV.


Soundness of the King's Indian Defence It is rarely seen at top level nowadays, but in the times of Fischer and Kasparov vs. Karpov matches, it was a very popular opening for Black.

I heard that Kramnik made Kasparov stop playing KID and that the Bayonet attack is one of the main reasons that KID is not played so often anymore.

Is the KID considered to be unsound at the top level today? What are the key games that caused this shift in popularity of the KID?

Actually the King's Indian has seen a recent rise in popularity. For a few years now, players like Nakamura and Radjabov have revitalised the opening. And if you take a look at the very recent top level games it is striking how many top players gave it a try: Nakamura, Jobava, Grischuk, Giri, Radjabov, Kasimdzhanov, Bacrot and quite consistently Ding Liren, just to name a few.

Those are all games from 2015 and the list reads like a who's who in top level chess. So there certainly is no big theoretical issue, that would dissuade black from playing the King's Indian.

One of the hottest lines right now is the 6.h3 line (white's choice in most of the games I linked), apparently Aronian introduced some tricky ideas for white in this variation (according to Seirawan).

I have heard this Kramnik-Bayonet-story before, but I'm not sure how close it is to the truth. Kasparov himself said, that he stopped playing the King's Indian because it became too much work to keep up with two ultra-sharp black defences (The other being the Najdorf). A few years ago the Bayonet-variation was still widely played (Nakamura scored some impressive wins against it), but for now the focus seems to have shifted to 6.h3.


Where to find links to live PGNs from major tournaments? This is follow up to my previous question about live broadcast format.

I was looking at TWICs Live Games, but there is usually only Live redirecting me to some higher level solution like Chess24 or to organiser's web. There is only occassionally PGN link and it often holds games from previous rounds etc.

Can I get access to these low level live PGNs during round easily or
is it more about contacting organisers to get such a link?
Is there some provider for such low level data, offering raw PGN content from live broadcast instead of some higher level solution?

Suppose you are running a big/important tournament. You want your games broadcast live on the internet. What do you do?

First, you need the equipment - DGT boards and sets, cables, a laptop with an internet connection plus the associated software which will collect the information from the sets, put into pgn files and send to an IP address or email address at suitable intervals.

Second, you need either your own website set up to accept and display these games on the internet or you need an agreement with somebody like chess24.com that they will host your games on their site so people can follow them.

Once you understand that you also understand the answer to your questions. As you say in your intro TWIC tells you the answer. The pgn data is being sent to the organizer's website and/or an independent host like chess24.com. It is in not broadcast universally.

There are only two ways to get the information.

Contact the organizers to get them to send you the files also (but why should they?)
Write a screenscrape program to extract the data from the hosting site.


Chess engine with danger (mate) warnings for beginners? I am new to the site and would appreciate help in this area.

At my current stage (beginner) I have started to draw or sometimes even beat the computer at low levels (ex. chess.com level1,2,3, lichess.org level1,2). One of these sites has an interesting feature that helps me a lot, it is a set of 3 numbers like a score. Here is an example of a game where I play White and I am behind 2 pawns (-2pts in material):

        +2.90
        -1.78
        -2.14
        Stockfish.js 8 | depth=19

Which I interpret the following way:

Positional score shows max=+2.90, which means that there is a tactic opportunity involved (overloading? removal of defender?...etc I must find out!).
If I see the opportunity and play correctly, I can materialize the advantage and win an important piece (maybe win a rook, or take the queen in exchange of one of my rooks)
If I miss the opportunity, the next score will be -1.78 (second best move) or -2.14 (third best move).
That is, the momentary positional advantage will disappear and the score will revert to the material strength (2 pawns behind).

Well, my problem is that I sometimes blunder and my score goes abruptly down to for instance -M2 [mate-in-2 for Black].
I lose the game :( because I did not realize that there was a mate danger (ex: last rank weakness or something like that).
The score of the site I am playing only shows the 3 best moves, not the WORST moves.

I am formulating this question here in the hope that someone knows other sites for beginners, with an engine that can be tuned to warn if there is a risk of blundering and being prematurely mated.
If I do not find such feature, well, I will have to be patient and continue with the learning process:). The frequency of blunders should decrease as I gain experience.

Thank you for your help.

Showing only the worst moves for a position is not something you'll find. Computer engines are not appropriate for warning against risk of blunders. My suggestions:

Take back a move against computer if you make a bad move
Review your game

You're asking the question because you're afraid of losing. There's no shame to lose against a computer. You learn more by going back your game (or takeback) then explicitly being warned.


How do I create pgn files visually? I'm looking for a way to create PGN files visually - so I don't want to type in the position and the moves manually, but I want to set up an initial position on a board, play some moves and then export that as a PGN file. Actually, I'm ok even if I can't play moves, but I do want to be able to setup the board and then export it either as a FEN or PGN string or file.
I've seen the online tool http://www.chess.com/analysis-board-editor, but is there anything I can use offline?
I'm on windows. And I would prefer free/open source.

I've been using fritz and that serves your purpose.

After you have installed fritz go to little arrow below the 'new game' and click on 'position setup'. After you finish setting your position, there is an option called 'copy FEN' on the same window and you can use that.

And if you want PGN, after setting up the position click OK, make moves you want to and click on 'copy game'and the pgn will be copied to the clip board and you can paste anywhere you want to.


How to measure Leela Chess Zero improvement I searched Leela website for some statistics about its self-training, the number of games it played with itself in order to assess its progress or to be able to predict whether it is going to win the next Sufi, for example, but I did not find any information.
What is the number of self-games it played before TCEC S19 or TCEC S20, for example? Where can this information be found? Are there any other characteristics to be used to measure its improvement?

The number of games doesn't really effect improvement.
Let's say that in the 500th game that is discovers the common Nf7 fork.  This knowledge isn't useful until it plays enough games to discover that the rook is worth mort than a knight.  Both pieces of information is needed, plus and ability to associate them, to understand that the fork is a positive play.  And we also have to discover when there is an exception to the general rule, ie when castling pins the knight or the wasted moves justify a viscous attack.
The improvement is randomly found, so this play could discover the usefulness and exceptions within 500 games, or it may never stumble across it within 1,000,000.  I've seen people make master before they ever saw the Scholar's Mate, which he fell into that trap, so number of games, intelligence, nor strength of the player are any indication of knowledge of any position.


What is the best way to solve chess puzzles? Doing puzzles at lichess.org I stuck at raiting 1750 +- 50. I cant really go over 1800. So what are the first things one should check by solving puzzles? Are there some tricks how to solve puzzles?

I had hit a plateau like you. Probably spent about two years at the same tactical rating level until I watched a video on chess.com (it's a series, actually, by IM dpruess "Exercises to Become A Tactical Genius") that reshaped my thinking entirely.

What I used to do was analyze each of my pieces, one by one, and explore the possibilities of each piece. It was almost a guess-and-check type methodology. Often I'd get the puzzle correct, but I took so long at doing it that my tactical rating would only go up only one point. In a game, doing this, I'd surely lose on time before arriving at the correct combination.

The video I'm referring to got me thinking in terms of concepts first and only then explore those moves that would play to the concept that stuck out the most in the position.

My recommendation to you is to first familiarize yourself with a complete list of tactical concepts. Then, when you are looking at your next tactical position, see if you can spot the concept or concepts that might be featured in the position so that you can look for ways to exploit that feature. For instance, if you notice a piece is pinned, see if any moves jump out at you that will make good use of that fact. In my experience, this technique will save you a lot of time because you'll find yourself only analyzing a small subset of possible moves and the odds that the right moves are in that subset will be high.

As a word of caution, be prepared to see your tactical rating take a big dip while you get used to this new way of thinking, but I believe that once you get the hang of this way of thinking, you'll see your tactical rating shoot up. For instance, I found my rating plateau at 1900 for a couple of years, changed to this way of thinking and saw it drop to maybe 1800 and then shoot up to 2300. All the best to you. I hope this helps.


Game drawn without enough material to mate even if opponent runs out of time? Does this apply to OTB chess as well?  I was playing an online game on FICS and my opponent ran out of time, but I did not have enough material to mate, so the game was drawn.

Yes.
This is an official rule, see Article 6: The chess clock of the FIDE rules handbook (E.I.01A. Laws of Chess). Section 6.9 goes :

Except [in checkmate and stalemate cases, mutually agreed draws and resigned games,] if a player does not complete the prescribed number of moves in the allotted time, the game is lost by the player.
However, the game is drawn, if the position is such that the opponent cannot checkmate the player’s king by any possible series of legal moves.


Minimax and alpha beta I want to implement a simple chess bot so I have been reading about this algorithm a lot. I can say I understand the basic idea of the algorithm but I can't clearly see how am I supposed to apply it on the board.
Let's say it's white turn, do i have to apply minimax on every possible move of all the white pieces ? And let's suppose the depth is greater than 1. Let's suppose I'm going to apply the algorithm on a pawn. As far as i understand I need to generate all the possible legal moves of my pawn, and for each move I'm going to apply (recursively) minimax again for the black side, at this point do I need to apply it on every single legal move of the black side? Is my understanding correct? If not would you please explain how is it supposed to work with an example?

Short answer:  Yes with minimax you have to search every move.

Minimax is not used due to the exponentially growing search which quickly becomes too big to be useful.  Think O(n2) sort functions.
Many concepts are used to help reduce the number of nodes the search function.  Transposition Tables, fail-safe, branch pruning...

https://web.archive.org/web/20071026090003/http://www.brucemo.com/compchess/programming/index.htm is the Gerbil chess engine with good explanations.

https://chessprogramming.wikispaces.com/Home is more general and discusses other algorithms, but is more technical and is closing soon.


Is there an online database for the endgame KRPPKRP? It was stated at this forum that the 7-men-endgames are still not available online.

What about the special endgame KRPPKRP (Rook and 2 pawns against Rook and 1 pawn) ?

It would be nice if the database covers also DTC or DTZ, ideally both.

All of the Syzygy tablebases are available here: https://syzygy-tables.info/

These cover all endgames up to 7-man, and provide WDL (win-draw-loss) and DTZ (distance to zeroing move) data.  Syzygy also distinguishes between a theoretical win or loss that can actually be forced into a draw by the 50-move rule, and one that cannot.

Here's an example for KRPPvKRP.


Representing Moves found via BitBoards, applying them, and removing them I understand how to find all valid moves for all pieces on the board. For example I know that a certain knight can hit all of the 1's in this board

01000000
00100000
N0000000
00100000
01000000
00000000
00000000
00000000

How do I store these as individual moves, how do I apply them to my BitBoards, how do I take back the move?

I've already written an engine before, but I did not use bitboards.

This is a very deep subject, but here's a few basic thoughts that might get you going.

A bitboard consists of 64 bits. If you designate one corner of the board as the most-significant bit and the opposite corner as the least-significant bit, you can store a bitboard in a single 64-bit integer.

For example, suppose A1 is the LSB and H8 is the MSB. We will fill up the 64-bit integer moving left-to-right (A-to-H) and then down-to-up (1-to-8). Your sample turns into:

0000000000000000000000000100000000100000000000000010000001000000

and this 64-bit integer represents the possible "landing" locations of a knight located at A6. In C this could be stored like:

long long knight_a6 = 0x4020002040;

We can do this for every possible location of the knight, in the same order that we filled out the bitboard (left-to-right, down-to-up). In other words:

A1: 0000000000100000010000000000000000000000000000000000000000000000
A2: <bitboard for a knight at A2>
...
B1: <bitboard for a knight at B1>
...
H8: <bitboard for a knight at H8>

This will take up 64 entries * 64 bits each = 512 bytes of space. Now we can determine the possible landing locations of a knight at any location, just by looking at the corresponding entry in the table. In C it could look something like this:

long long knight[64] = { 0x0020400000000000,
                         <bitboard for a knight at A2>,
                         ... };
long long knight_a6 = knight[40]; /* A6 = index 40 */

These are all static bitboards: they're just there for your convenience when programming. But you'll probably also want some active bitboards that represent the state of the game. For example, you'll probably want a bitboard that represents where all the pieces are. At the start of the game ranks 1, 2, 7, and 8 are full, so the bitboard looks like this:

1111111111111111000000000000000000000000000000001111111111111111

Or in C:

long long game = 0xFFFF00000000FFFF;

So what can you do with bitboards? Well, for starters you can determine if a piece (say, a knight at A6) is attacking another piece. To do this you perform a logical AND between the game bitboard and the static bitboard for the attacking piece. Let's say the game looks like this:

00000000
00k00000
N0000000
00000000
00000000
00000000
00000000
000000K0

The white king is on G1, the white knight is on A6, and the black king is on C7. The game bitboard would look like this:

0000001000000000000000000000000000000000100000000010000000000000

Let's see if the white knight is putting the black king in check. First, we look up the white knight's "landing" bitboard as described earlier.

0000000000000000000000000100000000100000000000000010000001000000

Now we AND that bitboard together with our game bitboard.

    0000001000000000000000000000000000000000100000000010000000000000
AND 0000000000000000000000000100000000100000000000000010000001000000
    ----------------------------------------------------------------
    0000000000000000000000000000000000000000000000000010000000000000

The result is not all-zeroes, so the selected piece is attacking something. Here's it is in C:

long long game = 0x200000000802000;
long long attacker = knight[40]; /* A6 = index 40 */
if (game & attacker != 0)
{
  /* The knight at A6 is attacking something! */
}

The next step is to see what he's attacking. There are multiple ways to do this: you could see where the 1 appeared in the ANDed bitboard and find the corresponding square, or you could keep a bitboard for every different type of piece. Let's leave it at that for now though.

Next let's see how pieces can be moved. We'll remove the black king from the board for simplicity.

00000000
00000000
N0000000
00000000
00000000
00000000
00000000
000000K0

Bitboard: 0000001000000000000000000000000000000000100000000000000000000000

Looking at the knight's landing bitboard we can see there are four one's, so four possible moves. Let's take the first one - so we'll erase all the other zeroes in the bitboard for now.

0000000000000000000000000100000000000000000000000000000000000000

To move the knight, we erase him from the game bitboard, and then AND the game bitboard with the knight's move bitboard.

       0000001000000000000000000000000000000000100000000000000000000000
ERASE  0000000000000000000000000000000000000000100000000000000000000000
       ----------------------------------------------------------------
       0000001000000000000000000000000000000000000000000000000000000000
OR     0000000000000000000000000100000000000000000000000000000000000000
       ----------------------------------------------------------------
       0000001000000000000000000100000000000000000000000000000000000000

The new gameboard looks like this:

00000000
00000000
00000000
00000000
0N000000
00000000
00000000
000000K0

Now, there are a lot of things brushed over in this answer:

How do you track what kind of piece is at each location?
How do you distinguish between white and black?
How do you distinguish between captures and normal moves?
How do you determine which squares are "shielded" behind another piece?
How do you handle pawns, which move in a different way than they capture?
How do you handle the initial pawn move and capture en passant?

Not all bitboards are the same, either. What if we filled out the bitboard in a fancier order than just going left-to-right, bottom-to-top? Maybe there's some other way to assign squares to bits that makes certain checks or moves faster. The way we've written it is just the simplest to picture.

Again, this is a very deep subject, but hopefully this at least explained some of the basics about how bitboards are used.


How was the FIDE rating system introduced? I am looking for a historical summary on how the first Elo ratings came about. Apparently in the first official rating list from 1971 there are already ratings in the range of 2200 to 2760. What are these based on? Did they actually run rated tournaments before this date, or did they calculate ratings based on the results in previous tournaments (which tournaments?)?

Also, initially did all players start with the same rating (which)?

In Robert Howard's article "A complete database of international chess players and chess performance ratings for varied longitudinal studies" (Behavior Research Methods 2006, 38 (4), pp. 698-703) he writes:

  The first FIDE rating list is dated December 1970 and was based on
  games in international tournaments in approximately the previous 2
  years.

I guess that Arpad Elo will describe this procedure in more detail in his book "The Rating of Chessplayers, Past and Present" that, unfortunately, I do not own.


Is there an engine which tries to find moves that forces the opponent to find the best move? For example:

1r1q2k1/1p3rpp/b1pn4/P5N1/1B1P4/1Q6/1P3PPP/2R3K1 w - - 0 1

Here, the best move is not 1.Bxd6 but White plays it anyway in a swindle attempt to win, since Black is forced to take on g5 (and not d6) to keep the advantage.

The short answer is no (as far as I know). You're adding together two concepts, so let me try to address them both:

Moves that have responses that are hard to find. This is a tough problem because it basically means running a regular computer engine and a more human-like engine at the same time, and seeing what moves are found by the first but not the second. People gave up on human-like engines a while ago because the more brute-force was so much more effective. So this is a tough research problem (one that people worked on for decades in the 20th century) without a big payoff.
Moves that are forcing. If the opponent has only one good response, that increases the chance that she'll play a bad move, right? Well, not really; if I play a capturing move and the only good move is a recapture, chances are my opponent will find it. So just using the number of good responses as a measure of how tricky a move is problematic. (Forcing moves are usually good to consider because they limit the search tree and increase the chance that all leaves in it are good for you, but that's a different reason from trying to induce a mistake.)

It would be nice to have an engine whose evaluations were "How likely would I be to win from this position against another 2000 player?" rather than "How likely would a computer be to win from this position against another computer?" but people have overwhelmingly concentrated on the later. (I would be delighted to be wrong about this.)


Who said "One bad move nullifies forty good ones"? This quote is attributed both to Bernhard Horwitz and I.A. Horowitz, and I'd like to know which one said it.

One thing that helps is they don't have overlapping lifespans. Bernhard Horwitz died in 1885 and I.A. Horowitz was born in 1907. We can probably safely assume that, if I.A. Horowitz said it, he had to have been at least 20 years old, so an attribution to Bernhard Horwitz from before 1927 should be considered reliable. Likewise, if no references to this quote before 1927 can be found, then it's probably I.A. Horowitz.

Alternatively, we might find a source that gives a more detailed attribution, such as "Bernhard Horwitz uttered this at such-and-such tournament" or "I.A. Horowitz wrote this in the January 1935 issue of Chess Review".

My hunch is it was I.A. Horowitz because he wrote for The New York Times and Chess Review, so he was a prolific author, so he had many chances to say something notable. Still, Bernhard Horwitz did write at least one book, and it does seem more likely for a quote by Horwitz to be misattributed to the better known Horowitz than vice versa.

According to chesshistory.com, in October 1959, Al Horowitz wrote:

  It is axiomatic in chess that it is easier to achieve a winning game
  than to win it. One bad move nullifies 40 good ones, and precision
  technique is of the essence even when the game is well in hand.

The same can be found in his book, “All About Chess”, written in 1971.

However, in the Chess Review magazine (November 1961), Al Horowitz calls this quote an “adage”.  Given this, I think that Al Horowitz is not the author of the quote, but thanks to him we know about it.

As for Bernhard Horwitz, I have not found reliable sources indicating that he is the author of the quote. At least, it is strange to me that it is not mentioned in his books.


Did Richard Teichmann fail to take his "bishop pair" idea to its logical conclusion? Playing Black in a game against J.R. Capablanca, Richard Teichmann accepted an isolated queen pawn as the price for getting a bishop pair

On move 20, White played Nf5, attacking his black squared bishop on e7, which was protecting his pinned knight on f5. He accepted the exchange of the knight for his good bishop, then had to sacrifice the h pawn to free his king from the resulting pin.

[fen ""]
[Event "Berlin exh"]
[Site "Berlin"]
[Date "1913.11.20"]
[EventDate "?"]
[Round "2"]
[Result "1-0"]
[White "Jose Raul Capablanca"]
[Black "Richard Teichmann"]
[ECO "D63"]
[WhiteElo "?"]
[BlackElo "?"]
[PlyCount "75"]

1.d4 d5 2.Nf3 Nf6 3.c4 e6 4.Bg5 Be7 5.Nc3 Nbd7 6.e3 O-O 7.Rc1
b6 8.cxd5 exd5 9.Bb5 Bb7 10.O-O a6 11.Ba4 Rc8 12.Qe2 c5
13.dxc5 Nxc5 14.Rfd1 Nxa4 15.Nxa4 b5 16.Rxc8 Qxc8 17.Nc3 Qc4
18.Nd4 Qxe2 19.Ncxe2 Rc8 20.Nf5 Kf8 21.Nxe7 Kxe7 22.Nd4 g6
23.f3 h6 24.Bxh6 Nd7 25.h4 Nc5 26.Bf4 Ne6 27.Nxe6 Kxe6 28.Rd2
Rh8 29.Rc2 Rc8 30.Rxc8 Bxc8 31.Kf2 d4 32.exd4 Kd5 33.Ke3 Be6
34.Kd3 Kc6 35.a3 Bc4+ 36.Ke3 Be6 37.Bh6 Kd5 38.Bg7 1-0

Teichmann's alternative was to move the bishop back to f8, allowing White to take the knight (and double his pawns on the f file). In that case, he would have two bishops against two knights to compensate for his wrecked pawn structure.

Teichmann was down a clear pawn after the way he played, counting on bishops of opposite color to give him a draw. Would he have been at less of a disadvantage playing the way I outlined in the previous paragraph, given that two knights are worth less than two bishops?

I'm not going to claim in a black-and-white way that your idea of 20...Bf8 is strictly inferior to Teichmann's 20...Kf8 in objective terms, but I can think of two solid reasons not to play into the resulting 20...Bf8 21.Bxf6 gxf6:

Contrary to your general operating premise that two bishops are superior to two knights, in this position White's knights are fantastic, and in particular, Black's poor pawn structure is such that the knights have wonderful outposts to camp in, as well as weak pawns to target down the road. Really, I'd take either of these knights over either bishop in this situation, so much so that if I were playing Black from this point on, I think I'd feel compelled to trade one of the bishops for a knight at some point anyway, and so I'd rather have done so without having compromised my pawn structure in this way.
White's position in this line is much easier to play. White has no structural weaknesses, while Black has targets in her structure. The knights have natural squares screaming out for occupation, while the light-square bishop is especially hemmed in, not least because of the isolated d5 pawn.

It's tough to give detailed analysis of variations without inline commenting, so I'll just illustrate what I mean with a single line. After, say, 22.g4 to make luft for the king and grab space on the kingside, even a seemingly productive move like 22...Rc2?! for Black doesn't actually lead anywhere, basically because of the pluses indicated above. For instance, after 23.Ned4 Black can't follow up with 23...Rxb2?, because after 24.Rc1! White will gain a big edge while Black looks after her inferior pieces: e.g. 24...a5 (forced, as otherwise the b7 bishop will be embarrassed) 25.Rc7 Ba6 26.Ra7 Bc8 27.Rxa5 and White has a huge plus. Even if it doesn't look that way at first glance, if one plays around with this position a bit, it's much easier to find good moves for White, and it's actually quite difficult to bring the black pieces (including the king) into play without running into trouble.

[fen "2r3k1/1b2bppp/p4n2/1p1p1NB1/8/4P3/PP2NPPP/3R2K1 b - - 0 1"]

1...Bf8 2.Bxf6 gxf6 3.g4 Rc2?! 4.Ned4 Rxb2? 5.Rc1! a5 6.Rc7 Ba6 7.Ra7 Bc8 8.Rxa5

Again, that's just one illustrative line, and certainly one in which I picked a mistaken idea for Black for effect. But the point is, if Black can't effectively make an active threat like the one indicated without facing such a harsh backlash, then it's not a position in which Black has much of anything to play for, and instead is one through which Black must suffer and just hope to hold on. To me, that's reason enough not to go in for this option over 20...Kf8.