Data set of board representations at checkmate? I would like to do a simple project by looking at the pieces at play when checkmate occurs.

I have been scouring the internet for a dataset of standard chess games from which I can retrieve the final board representation, where a checkmate has been played to it's conclusion.

At this point, any board representation would have to be fine, although I'm not trying to generate moves or anything, thus array based would be ideal.

I'd need to have the graphical representation (i.e., like a screenshot a way to load up the games to view them), so I could organize by hand. Well, by sight, actually.

If anyone has any ideas, I'd be grateful.

Monica

To get you started, here's one way you could do this on your own in Python with the python-chess module:

In the example we're loading a simple pgn-file for illustration (which you generalize to reading pgns from a loaded database using the same module) and extracting its final position as a bitboard.
Then we check if it's a checkmate position, if true, you can extract the pieces on the board as a Square Set.
From that, you can then transform the data in any form, e.g. as lists or arrays of the piece symbols and corresponding squares (shown below), or however else it suits your follow-up purposes best.

Here's the snippet for that:

import chess
import chess.pgn
import sys

arguments = sys.argv
pgnfilename = str(arguments[1])

#Read pgn file:
with open(pgnfilename) as f:
    game = chess.pgn.read_game(f)

#Go to the end of the game and create a chess.Board() from it:
game = game.end()
board = game.board()

if board.is_checkmate():
    print "checkmate found: "
    print board

    white_pieces = [(board.piece_at(sq),sq) for sq in chess.SquareSet(board.occupied_co[1])]
    black_pieces = [(board.piece_at(sq),sq) for sq in chess.SquareSet(board.occupied_co[0])]

    print "white pieces: "
    for el in white_pieces:
        print el[0].symbol(), " on ", chess.SQUARE_NAMES[el[1]]

    print "---------------------"
    print "black pieces: "
    for el in black_pieces:
        print el[0].symbol(), " on ", chess.SQUARE_NAMES[el[1]]

Which gives the following output for the downloaded PGN of this game between Alexander Alekhine vs Oscar Tenner:

r . . q . . . r
p p p . . B p p
. . . . . . . .
. . B . k R . n
. . . . P . . .
. . . P . . . .
P P P . . . P P
R . . b . . K .
white pieces:
R  on  a1
K  on  g1
P  on  a2
P  on  b2
P  on  c2
P  on  g2
P  on  h2
P  on  d3
P  on  e4
B  on  c5
R  on  f5
B  on  f7
---------------------
black pieces:
b  on  d1
k  on  e5
n  on  h5
p  on  a7
p  on  b7
p  on  c7
p  on  g7
p  on  h7
r  on  a8
q  on  d8
r  on  h8

Additional details and ways of extension:

Conventionally, capital and small symbols are used for white and black pieces respectively. For a better display of the board, you can use the Unicode symbols for chess pieces and encode them appropriately (depending on your python installation or possibly OS) for printing. In our example above, you could have immediately retained the Unicode of each piece instead of its symbol, board.piece_at(sq).unicode_symbol()
Given a PGN-formatted database (e.g., using TWIC PGNS), you can easily load it by reading it in python and extracting the starting/ending line indices of each game[*] in the database, and in a loop over all games, you pass each game as a PGN file to chess.pgn.read_game and the rest follows similarly as in the snippet above.

Feel free to ask in comments if you have any questions about the snippet and other ways of extending it.

[*]: All this depends on the database you're trying to work with, but once the formatting known, then you can e.g., parse games based on a keyword that occurs at the start of each game in the database, for instance in the TWIC ones, there's always a line with Event .. in the headers of the PGN, or even the empty lines between the games. However you go about it, once you know the starting and ending line indices of a game within the file, you can pass it to chess.pgn.read_game as a file-like object with cStringIO.StringIO in python. It's not the most efficient way necessarily, but it does the trick.


Why is increment more popular than delay? Increment is FIDE's default for their tournaments, although their rules permit delay as well. Most internet chess servers also use increment exclusively.

As I understand it, delay is used by the USCF (for historic reasons?), and, for some reason, by the 2017 Grand Chess Tour.

Why is increment preferred over delay by pretty much everyone but the USCF?

Very simple. Move quickly (faster than the increment) and you end up with more time. Over the course of a dozen or so quickly made moves you can build up enough time to allow for another serious think if required.

With delay you can never get more time. Once in zeitnot you are permanently in zeitnot.


Why Are Openings Named After Countries? This has been bothering me from when I was little. Why are openings most commonly named after a country? For example: Sicilian, Scotch, Spanish, etc...

There's a variety of reasons why openings are commonly named after nations (but most commonly would surprise me), maybe due to an individual player of the nation, e.g. Spanish (Ruy Lopez), English (Staunton), maybe due to a group of players in one nation e.g. Italian, maybe due to an event involving the nation e.g. Scotch (named for a correspondence match between Edinburgh and London in the 1800s), and I suspect a number of other reasons, including "we don't really know"

Wikipedia list of chess openings named after places might be a good place to start researching this


The Ponziani - What are the plans? We live in a strange country. Instead of having championships for all group ages(U10, U12, etc) they just place everyone in a tournament and ship the top people of each group-age. I am third best in the U18(not because I'm a born talent, but because of lack of talents), and I have two competitors. The Nr.1 has beaten several IMs, the second one just got a 2070 rating in his first tournament ever, so you realize my situation. Not only do I have to face them in my group age, but also several other talented kids. So to make sure, I am going to use an offbeat, yet great opening, the Ponziani. I am sure no one knows this.

I have seen several opening lines of this, but I want to know what are the plans in the:

Nf6 variation
d5 variation
f5 variation
Other minor variations

The Ponziani move order is that shown on the board below:

[Fen ""]
1. e4 e5 2. Nf3 Nc6 3. c3

With 3. c3, White aims to:

Prepare the pawn push d4
Avoid the Ruy Lopez & Italian game lines, though transpositions can occur
The down side of this non-developing move is that the queen-side knight is deprived of its best square. White often sacrifices material or structure (by accepting an isolated Queen's pawn) to develop.

In response to this, Black has 3 main moves.

3...Nf6

r1bqkbnr/pppp1ppp/2n5/4p3/4P3/2P2N2/PP1P1PPP/RNBQKB1R b KQkq - 0 3

3...Nf6 4. d4

Now, Black can accept the gambit with 4...Nxe4. Play goes 5. d5 Ne7. 5...Nb8 is also played, but less often than 5...Ne7. White's plan here is as with an gambit - build a development lead, keep the initiative & attack.

Or, he can accept the pawn with 4...exd4. Play goes 5. e5 Ne4 6. Qe2 d(f)5 7. exd(f)5 e.p., opening the position. White often gets an isolated Queen's paw position in these lines, which should be played like a gambit (keep the initiative, avoid trades & attack).

Lastly, Black can play 4...d5, leading to a complex game with lots of central tension. Play goes 5. Bb5 aims to develop & prepare tactics based on the theme of removing the defender.

3...d5

r1bqkbnr/pppp1ppp/2n5/4p3/4P3/2P2N2/PP1P1PPP/RNBQKB1R b KQkq - 0 3

3...d5 4. Qa4

Play can go 4... Qd6 5. Na3 (preparing to attack the Queen) Nf6 6. Nb5 Qe7 7. d3, and White has better development, a space advantage & a solid structure.

Play can also become very complicated with 4... Bd7 exd5 5. Nd4, where Black is trying to develop with tactics against the Queen.

3...f5!?

r1bqkbnr/pppp1ppp/2n5/4p3/4P3/2P2N2/PP1P1PPP/RNBQKB1R b KQkq - 0 3

3...f5 4. exf5 Qf6

This is a gambit with play similar to the Latvian gambit.


Chess puzzles in newspapers and magazines which offer a prize I like chess puzzles, and particularly like those for which there is a prize.

The Times, Sunday Times and Spectator provide weekly puzzles (I'm based in the UK). These puzzles are available online as well as printed. I can usually answer two of these and, in good week, all three.

I'd like to know of other sources of chess puzzles in the press or on the web which offer a modest reward. Do you know of any?

The only one I am aware of is chesspuzzles.com offering a prize drawing for:

Mate in 1 problem: Chess Rules for Students (RRP $4.50)
Mate in 2 problem: Checkmate! Ideas for Students (RRP $5.00)
Mate in 3 problem: Chess Tactics for Students (RRP $16.00, but on sales for $12.80 now)

All prizes written by John Bain. The latest prize drawing was week ending Saturday 16-December-2016, at the time of answering this post.


Is there software or a device that allows bookmarking positions to allow variation analysis? I'm wondering if there is any chess software or portable chess computer that allows a position to be bookmarked while a variation is examined?
For example, it's possible to download pgn for games analyzed in Chernev's logical chess. However, there isn't a diagram for every position, and occasionally the author outlines alternate moves and their consequences. While it's possible to follow through this analysis on a board and "unplay" the moves back to the point where this divergence from the actual game takes place, this can be time-consuming. What I'm looking for is the opportunity to bookmark a point in the game, follow the variation through, and then click back to the bookmark to continue on with the game, rather than clicking a back arrow for every move that was made.
Thanks

Chessbase is a commercial product that solves your problem.  Any position in Chessbase is in essence a bookmark.  You can just click on the move/position you want to go back to (all the moves are available visually beside the chess board).  I believe the same functionality is available for free with Scid.


How can white mate black in 4 moves? In this endgame position, how can black be mated in 4 moves? Being a beginner, I am finding it difficult

[FEN "8/8/6R1/8/8/4K2p/7k/8 w - - 0 1"]

Use the king to keep the black king in the corner and force Black into zugzwang:

[FEN "8/8/6R1/8/8/4K2p/7k/8 w - - 0 1"]

1.Kf2 Kh1 2. Re6 Kh2 (2... h2 3. Re1) 3. Rh6 Kh1 4.Rxh3


How useful is a 40-year-old chess book? I have a chess book which I find great in terms of tone, formatting, etc., but the computer does not agree with some variations I gave it.

How much has chess changed since 1977? I imagine the rise of the computers (and computer chess) the last couple of decades had quite some impact. Is my book (published in 1977) still worth reading?

I'd like to know before I buy the other books of the series.

Addendum
The series in question is "praktische schaaklessen" (practical chess lessons) by Euwe. The book I have is on opening theory, but the other parts are on the other aspects and stages of the game (it's a six book series).

This depends on a lot of things, but most importantly: your playing level and the topic.

For example, if it is an opening book, it heavily depends on the opening. Some opening variations which are main stream today, didn't even exist in the seventies, or were rarely used (like the Berlin Wall in Ruy Lopez). Others haven't seen that much development (QGD, and offbeat openings like the King's Gambit).

Middlegame & strategy books usually last longer; Nimzowitsch' Mein System is 90 years old but still a useful read.
The same is true for endgame books, with one notable exception (which doesn't appear that often in practice): endgame tablebases have completely changed the view on certain endgames like K+Q vs. K+B+B (thought to be a draw, now known to be a win for the Q) and K+Q vs. K+N+N (the other way around).

If you are a <2200 player (like me), you shouldn't worry too much about computer evaluations. Though it is a very good practice to analyse the lines given by the books, so kudos for that.


Board order in chess olympiads What's stopping teams in chess olympiads from mixing up their board order to gain an advantage? All I could find was the rules (http://www.fide.com/FIDE/handbook/chess_olympiad_regulations.pdf) that said that the board order couldn't be switched in between rounds.

However, even without changing board order, being able to arrange the boards independently of playing strength can be used to gain an advantage. For example, suppose we had players A,B,C,D,D', where player A is stronger than player B, player B is stronger than player C, player C is stronger than player D, and player D is the same strength as player D'.

Instead of ordering the players by strength, we could put player D' at first board, and then place the remaining players by strength (so player A is second and so on).

In each round, we only play four players. If we have the first board sit out, we could get the usual board order by playing strength. However, we could also have the fifth board sit out, in which case we have shifted our top three boards down by one, which could be useful against a stronger opponent (especially one that is top heavy).

(Related question: Are the board positions of the 4 players of each country determined by Elo rating in chess olympiads?)

Well, in short, nothing. This (a tactical lineup) is actually quite common in team matches. There are basically two problems, the second of which is not a problem in the Olympiad because of the fixed board order.

Chess isn't an exact science; a weaker player can beat a stronger player (the odds that this happens are just lower). Given the ratings, you can calculate the expected score of a match where both teams are lined up in the regular way, and the expected score when one of the teams employs a tactical lineup. See below for some details.
If you do this too often, the opposing team can prepare and put their weakest player on board one (or even their second weakest player, putting their weakest player on board two, which results in them having a tactical lineup instead).

Here are some calculations based on the formula mentioned here for the expected score. As you see, the tactical lineup increases the expected score for the team by only 0.01 point.


When is a fianchetto strategic to play? I know that some openings include fianchettoing the bishop. But sometimes, this isn't part of the opening, but I still need to decide whether to bring my bishop one rank forward (like Bg7) or to the other side of the board (like Bc4).
Someone told me that usually the fianchetto is useless if you push the center pawn closer to the fianchetto's bishop.
What should I look for to decide whether I should fianchetto or bring my bishop further up the board?
Edit
As an example, in the Sicilian as Black, I usually do 1. e4 c5 2. Nf3 d6. At this point, I've already moved two pawns, so I am not going to do e5.

In a lot of cases you just rely on your intuition. With enough experience you can tell whether a fianchetto makes sense in setups like the Sicilian. But here are some tips for when to do it:

If the long diagonal is open, since the bishop will not be blocked along it.
If your opponent doesn't have a bishop on the same colour as the soon to be fianchettoed bishop. This will make it more difficult for your opponent to trade off your bishop. Note that if the bishop does get traded off, it's not a huge deal, but now there's a hole in front of your king.
If the bishop has no responsibilities on its normal diagonal of development. E.g., in the Sicilian, if you've pushed ...d6 and then either ...e6 or ...e5, your bishop is often important in defending the d6-pawn. So fianchettoing it here usually isn't recommended. But if the e-pawn is left on e7 (like in the Dragon), there are no issues with the d6-pawn when you fianchetto.
If it would take two moves to develop the bishop anyway along the normal development diagonal. I.e., if your e-pawn hasn't moved yet, you'll have to spend a tempo pushing it and then bringing out the bishop. This means that if you go for the fianchetto, at least it won't waste any extra time.

All of these guidelines can absolutely be broken though. They are just some things to factor into your decision -- each position should be treated on a case by case basis.


Can someone explain how this pawn endgame works? I'm sorry if this position has been asked before, but can someone explain how it works?

[Event "?"]
[Site "?"]
[Date "????.??.??"]
[Round "?"]
[White "?"]
[Black "?"]
[Result "*"]
[FEN "8/4k3/3p4/3P4/2P5/8/8/5K2 w - - 0 1"]

1.Kg2 Kf8 2.Kf2 Ke7 3.Kg3 Kf7 4.Kf3 Ke8 5.Kg4 Kf8 6.Kf4 Kg8 7.Ke4 Kf8 8.Kd4 Ke7 9.Kc3 Kd8 10.Kb4 Kc7 11.Ka5 Kb7 12.Kb5 Kc7 13.Ka6 Kd8 14.Kb6 Kd7 15.Kb7 Kd8 16.Kc6 Ke7 17.Kc7 Kf8 18.Kxd6 Kg7 19.Kc7 Kf8 20.d6 Kg7 21.d7 Kf8 22.d8=Q+ *

This is perfect play, but I don't understand it; can someone explain it?

I think considering an intermediate position first helps clarify what is going on. Consider the following position with Black to move. The white king is on d4, poised to head for infiltration on either the queenside or the kingside. The only drawing move for Black is to play 1...Kd8!, not committing to one side or the other. (For instance, 1...Ke7? reaches a position from the OP's main line, where White wins by heading to the other side via c3.) Playing through the variations and annotations below from this position will (hopefully) show how the opposition and distant opposition come into play rather immediately from this point.

[White "Intermediate"]
[Black "Position"]
[FEN "8/3k4/3p4/3P4/2PK4/8/8/8 b - - 0 1"]
[StartFlipped "0"]

1...Kd8 $1
    {This is the only drawing move. When the white king comes to d4, so
    long as the black king can play to d7 or d8, the game is still drawn.
    But if the black king has to commit to one side or the other (to the
    c-file or e-file) then the white king will be able to infiltrate on
    the other side.}
    ( 1...Ke7 $2 {This reaches a position from the OP's main line, where
    now White can infiltrate from the queenside.} 2.Kc3 $1 Kd7 3.Kb4 Kc7
    4.Ka5 $1 {Not giving Black the chance to steal back the opposition.}
        ( 4.Kb5 $2 Kb7 )
    )
    ( 1...Kc7 $2 {Going this direction lets White invade on the kingside.}
    2.Ke4 Kd8
        ( 2...Kb6 $5 {White must keep in mind this counterattacking idea,
        but it doesn't work out.} 3.Kf5 Kc5 4.Ke6 {White wins via the
        classic trebuchet.} )
    3.Kf5 Ke7 4.Kg6 Ke8 5.Kf6 Kd7 6.Kf7 Kd8 7.Ke6 Kc7 8.Ke7 )
2.Kc3
    ( 2.Ke4 Ke7 3.Kf5
        ( 3.Kf4 Kf6 )
    3...Kf7 {Black maintains the peace.} )
2...Kc7 3.Kb4
    ( 3.Kb3 Kb7 $1 {Again the only drawing move. Without maintaining the
    distant opposition, White can infiltrate.} )
3...Kb6
    {Black maintains the peace.}

Returning to the starting position, then, if White can maneuver his king to d4 in such a way that Black cannot play her king to the d-file in response, he will have a won game. What needs to be done to achieve that? White needs to force matters such that Black must either (1) allow the intermediate position where she can't get to the d-file, or (2) get outflanked and allow infiltration anyway. Use of the distant opposition is the only way for White to force such a decision onto Black; what complicates matters is that the mass of central pawns take squares away from each king, and that affects when one "really" has the (distant) opposition or not. The following variations and annotations attempt to show how this plays out, and to give a sense as to what considerations come into play. Certainly not every possible variation is given, but hopefully just enough wrong turns are explained to show what is going on.

[White "Starting"]
[Black "Position"]
[FEN "8/4k3/3p4/3P4/2P5/8/8/5K2 w - - 0 1"]

1.Kg2 $1
    {This, and only this, gives Black no way to grab the distant
    opposition. Whatever move is made now, White will be able to force an
    untenable decision onto Black.}
    ( 1.Kf2 $2 Kf6 $1 {Maintaining the distant opposition keeps the
    balance.}
        ( 1...Kf7 $2 2.Kf3 $1 {Stealing away the distant opposition, the
        only winning move.} 2...Kf6 3.Kf4 $1 {Keeping the opposition. Now
        Black has a choice. Either allow the White king to infiltrate
        along the outside of the kingside, or try to force the white king
        toward the center. The latter is more stubborn, but we end up in
        the intermediate position from above where the black king is
        overcommitted and cannot get to the d-file after Kd4.} 3...Ke7
            ( 3...Kg6 {Now on the g-file, there is no time to get back to
            the d-file when the white king heads to d4.} 4.Ke4 Kf6 5.Kd4
            Ke7 {Now we are in the OP's main line, and also the
            intermediate position where black has had to commit to the
            kingside and allow infiltration on the queenside.} )
        4.Kg5 Kf7 5.Kf5 Ke7 6.Kg6 Ke8 7.Kf6 Kd7 8.Kf7 Kd8 9.Ke6 Kc7 10.Ke7
        )
    2.Ke3 Ke7 $1 {Keeping the distant opposition, and not falling for an
    appealing alternative.}
        ( 2...Ke5 $2 {This looks like taking the opposition, but because
        d5 is unavailable, this is just a mistake.} 3.Kd3 $1 Kf6 4.Kc3 {
        Black won't be in time to keep White out of the queenside.} )
    3.Kd4 Kd7 $1 {Kd8 works as well. This is our intermediate position
    where Black just needs to be on the d-file.} )
    ( 1.Ke2 $2 {This also lets Black get the distant opposition.} 1...Ke8
    $1 {The only drawing move, taking the distant opposition.} 2.Kf3
        ( 2.Ke3 Ke7 $1 3.Kf3
            ( 3.Kf4 Kf6 )
            ( 3.Kd4 Kd7 {Safely on the d-file.} )
        3...Kf7 $1 )
    2...Kf7 $1 3.Ke4 Ke8 4.Kd4 Kd7 {Safely on the d-file.} )
1...Kf6 2.Kf2 $1
    {Only this, taking the distant opposition.}
2...Ke7
    ( 2...Ke5 3.Ke3 $1 Kf6 4.Kd4 Ke7 {The intermediate position, where
    Black hasn't stayed on the d-file.} )
    ( 2...Kf5 3.Kf3 Kf6 4.Kf4 {This is the same position as after 1.Kf2?
    Kf7? 2.Kf3! Kf6 3.Kf4 given in another variation. Either Black gets
    outflanked on the kingside, or allows the intermediate position
    unfavorable.} )
3.Kg3 $1
    {Starting to outflank, and doing so in such a way that Black cannot
    grab the distant opposition. Only this wins.}
    ( 3.Ke3 $2 {This looks like grabbing the distant opposition, but it
    cannot be maintained because of squares made unavailable by pawns. Now
    the game is drawn.} 3...Ke8 $1 {Only this. It prevents an unfavorable
    instance of the intermediate position, and allows Black to grab the
    distant opposition should White head toward the kingside.} 4.Kd4
        ( 4.Kf4
            ( 4.Kf3 Kf7 $1 )
        4...Kf8 $1 )
    4...Kd7 {Safely on the d-file.} )
3...Ke8
    ( 3...Kf6
        ( 3...Kf7 4.Kf3 $1 )
    4.Kf4 $1 )
4.Kg4 $1
    {Again not allowing Black to grab the distant opposition, and only
    this wins.}
4...Kf8 5.Kf4 $1
    {Only this.}
5...Kg8
    {Now that the black king is on the g-file, White can head for Kd4 and
    the intermediate position where the black king can't get back to the
    d-file.}
    ( 5...Ke7 6.Kg5 {Infiltrating as in other variations given.} 6...Kf7
    7.Kf5 Ke7 8.Kg6 Ke8 9.Kf6 Kd7 10.Kf7 Kd8 11.Ke6 Kc7 12.Ke7 )
6.Ke4 Kf7 7.Kd4 Ke7
    {White wins as in the OP's main line.}


Is one move considered as objectively better than another if they both lead to the same result? Here is an example
[FEN "8/3k2PB/q7/8/4K3/8/8/8 w - - 0 1"]

One might intuitively say g8=Q is a much better move than g8=R. However, since they both lead to a draw, should we not conclude that g8=Q is as good as g8=R?

Well, according to [Syzygy endgame tablebases](https://syzygy-tables.info/?fen=8/3k2PB/q7/8/4K3/8/8/8_w_-_-_0_1_, g8=R is a loss in 63 plies and g8=Q is a draw.  So g8=Q is definitely better.


Are there good variations for White against the Sicilian that do not involve an early d4? If White opens e4 and Black replies c5, that's the Sicilian defense. Typical next moves are 2. Nf3 d6 3.d4 cxd4 4. Nxd4, etc.

Are there good variations for White where he DOESN'T play d4?

I've heard of 3. b4 (Wing Gambit), but I don't like gambits.

Does it make sense for White to play d3 instead, either before or after Bc4?

It's quite common the Closed Sicilian, with, for example:

[FEN ""]
1.e4 c5 2.Nc3 Nc6 3.g3 g6 4.Bg2 Bg7 5.d3 d6

The Grand Prix Attack is of course another possible way to face any Black player after 1.e4 c5. Nowadays the main line is:

[FEN ""]
1.e4 c5 2.Nc3 Nc6 3.f4 g6 4.Nf3 Bg7

After 1.e4 c5 2.Nf3 (any) 3.g3 White can build a King's Indian Attack, which is less common and less sharp, but perfectly playable.

These variations are not as popular as the "Open" ones, but you may encounter them from time to time even during high-rated torunaments.


How rankings or ratings of the players are determined before the next tournament? My question is and I would like to know, Chess grandmasters Bobby Fischer[AMERICA}, Boris Spassky[RUSSIA], Anatoly Karpov[RUSSIA], and Garry Kasparov[Russia]played against one another in many tournaments in Big cities. How their ratings or rankings were determined? Are the only basis their past performances? OR those who are engaged in Bettings play their roles? please take a look at the list of chess grandmasters who are famous at the international level from 1970- 1982.

Are the only basis their past performances?

Yes

OR those who are engaged in Bettings play their roles?

None whatsoever.
According to the Olimpbase website:

Back in 1942 the USCF used its own chess rating system (Harkness) to
rank domestic players, while German Chess Federation did the same in
1948 (Ingo system). In 1959 one Arpad Elo was nominated chairman of
USCF rating committee and already in 1961 he published the very first
list of top US players in "Chess Life". Even though prof. Elo used to
publish his own, unofficial International Rating Lists it was 1970
FIDE Congress held in Siegen, Germany that adopted the Elo system for
official use. The first official list was to be published on 1st July
1971 and it was approved on consecutive FIDE congress in Vancouver,
Canada, in August 1971.

Elo's unofficial international ratings dating back to 1967 are available on the Olimpbase site as are FIDE ratings from 1971 to 2001. From 2001 the FIDE ratings lists are available on the FIDE website.


Why is ...a6 played in the Exchange Slav? [fen ""]
1. d4 d5 2. c4 c6 3. Nc3 Nf6 4. cxd5 cxd5 5. Bf4 Nc6 6. e3 a6

I do not see the point of this move. At first I thought it is aimed to prevent Bb5 and thus maintain the knight on c6, which controls e5, a square where White has a firm grip. It also prevents Nb5-c7, which is not yet a threat but might very well become one, as the White bishop is aiming at c7.
But after checking those threats aren't real and even if ...a6 is not played, in most continuations the best move for White is Bd3. Meanwhile the move ...a6 actually creates responsibilities (I would not yet say weaknesses, but work is required to avoid them) for Black, mainly because the advance ...b6 to control c5 leaves the queenside vulnerable (as demonstrated in Kramnik - Aronian 2012)

It prevents Nb5-c7. That's the main point behind the move. Just take a look at the disaster a careless move like 6...g6? could lead to.
6...a6 is not the only option, though. Black can try for instance 6...Bf5 (which is indeed more popular), intending to reply to 7.Nb5 with 7...Rc8. 6..e6 is another common move.
A good reason to prefer 6...a6 could be flexibility. 6...e6 makes it hard for the c8 bishop to find a good diagonal. 6...Bf5 could run into trouble against some Qb3


Can Black capitalize? I have played a game against a computer and came to the following position:

[Title "Black to move"]
[StartFlipped "1"]
[fen "3q2k1/pp1r1p1p/2p1p1p1/2Pr2P1/P2P1P2/4Q3/1P1R3P/3R2K1 b - - 0 1"]

I gave my best to capitalize, but in the end game was spectacularly drawn (3 queens were on the board at some point, but I have managed to save myself with perpetual check).

I feel sad because I believe that Black should be able to win the game from the position above.

Can you demonstrate a winning plan from this position?

After 1...b6! Black can win a pawn. Whether that will be a winning endgame or not is a different matter, but I don't see a better plan for Black. So 1...b6 looks like the most reasonable way to pursue a win.

[FEN "3q2k1/pp1r1p1p/2p1p1p1/2Pr2P1/P2P1P2/4Q3/1P1R3P/3R2K1 b - - 0 1"]
[White "Comp"]
[Black "ALNS"]

1... b6 2. cxb6 (2. b4 a5 3. cxb6 axb4 4. Rc1 Qxb6 5. Rc4 b3 6. Rb2 Rxd4 7.
Rxd4 (7. Rxb3 Rd1+ 8. Kg2 R7d2+ 9. Kf3 Qd8) 7... Qxd4 8. Qxd4 Rxd4 9. Rxb3 Rxa4
10. Rf3 Kf8) 2... axb6 3. b4 (3. Kf1 c5 4. Qe4 cxd4) (3. Rc2 c5 4. Rc4
cxd4) 3... c5 4. bxc5 bxc5 5. h4 cxd4


Rules: How does right to castle and en passant get considered for the purpose of calculating a threefold repetition? I'm writing a chess app, and have some questions regarding the intricacies of the threefold repetition rules.

As of 2018, the FIDE handbook has this to say about what constitutes identical positions for the purpose of threefold repetitions.

  9.2.2  Positions are considered the same if and only if the same player has the move, pieces of the same kind and colour occupy the
  same squares and the possible moves of all the pieces of both players
  are the same. Thus positions are not the same if:

  9.2.2.1   at the start of the sequence a pawn could have been captured en passant

  9.2.2.2   a king had castling rights with a rook that has not been moved, but forfeited these after moving. The castling rights are lost
  only after the king or rook is moved.

This question and Rule 9.2.2.2 address calculating right to castle. Looking at both, my conclusion is that it only checks whether the relevant piece(s) have moved; other restrictions like check, obstructions, or even whether the relevant rook was captured are not considered (though the last is probably irrelevant).

The same rule also seems to specify that each player starts with 2 castling rights- one for kingside and one for queenside- rather than 3- one for the king and one for each rook.

So the first part of my question is, am I correct in my assessment of how the right to castle affects whether positions are identical?

For the second part of my question, there seems to be a little ambiguity regarding en-passant.Rule 9.2.2.1 is clear about the case of if a pawn can legally en-passant one turn and can't during a later turn, then the positions aren't identical even if everything else is the same.

But there are two cases with en passant that aren't clear, or at least, should be clarified in light of how right to castle is calculated.

First, say a pawn moves two squares, thus making it capturable by en-passant, but there's no enemy pawn next to its destination. Does the fact that it would have been vulnerable to en passant make the position non-identical to another otherwise identical position a few turns later?

Second, say a pawn moves two squares, landing next to an enemy pawn, giving that pawn the right to en-passant, but where exercising the right to en-passant would expose the king (thus barring the otherwise legal en passant). Would that position be considered different from an otherwise identical position a few turns later?

You have identified the correct rule governing these situations. 9.2.2 is the relevant clause that applies; 9.2.2.1 and 9.2.2.2 are just clarifications of this rule.

So to answer your queries:

1) Your interpretation of castling rights is correct. Each player has two castling rights which are irrespective of the current board position. The right to castle short is lost only when the king or h-rook moves for the first time. The right to castle long is lost only when the king or a-rook moves for the first time. Other restrictions are irrelevant.

2) If a pawn moves two squares without an enemy pawn ready to capture en passant next to it, the position is the same as the one which could reoccur after some more moves. This is because all the players have the same possible (legal) moves (the relevant en passant is, was, and will be unavailable) so under 9.2.2 it would be the same position.

3) Similarly, if en passant is illegal due to a pin (exposing own king to check) or another reason, it does not count as a possible (legal) move, so under 9.2.2 the position and the repeated one later are considered the same.

An additional note: comparing FEN is not a correct implementation according to the FIDE rules, since FEN always records down a pawn moving two squares, regardless of whether an en passant capture is possible or not. Hence a direct PGN comparison would yield a wrong conclusion in the two scenarios you described.


Do you know this proof game? I'm not familiar with this proof game.
[FEN "r2qk1nr/ppp1pp1p/2n1p2p/8/8/1P6/NPPPPPPP/R3K2R w KQkq - 0 1"]

What square was the white queen captured and how?

The White Queen was captured on h6 by the Black Pawn.

The reasoning is as follows:

 * It is impossible for both White bishops to move from their start squares, so they were both captured by Black knights.

 * White's other two missing pieces are a knight and the queen. Black has two displaced pawns that are there as the result of captures (pawn on e6 and h6), So both of those pawns captured White pieces.

* Essentially the White queen developed from it's d1 start square to b1-a2 and then outside of White's pawn chain

* Which means the question is how did White's pawn get from a2 to b3. Black has no pawns missing. The Black queen and both knights are on the board, which means White's pawn capture of a2 to b3 was capturing the Black light-squared bishop (which started on c8).

* But, how did Black's bishop get from c8 to b3? Via the d7-square, which is unblocked by the black pawn capture d7xe6. That capture must have been of the missing White knight, because the White queen couldn't get to e6 to unblock the black dark-squared bishop.

So the time series of key events:

* Black's knights marauded around the board capturing both White bishops on their start squares, and returned to g8 and c6

* White's knight got to e6 and was captured by the black pawn on d7, thus allowing the Black light-squared bishop to develop. The other knight stayed on the queenside. One of White's knights captured the black dark-squared bishop on f8.

* Black's now freed bishop landed on b3, and was captured by the a2 pawn. This freed the White Queen

* The White queen developed via b1 and a2, reached h6 and was captured by the Black pawn on g7.


Which is better for an improving amateur to play even better: correspondence chess or faster time controls[both online]? Currently, I do the following in order to improve my chess:

Play several (currently 9) correspondence chess games simultaneously on Chess.com.

Do tactics and puzzles regularly on Lichess.com and Chess.com.

Play occasionally against the computer (though not full strength) in rapid time controls (10|15).

I chose to play correspondence chess as it provides me a  considerably good amount of time to think, and hence play to my best.
I also find that correspondence chess is easier to manage, as I don't have to be online throughout the game.
The thing is, correspondence chess moves so slowly, I feel that it would take me years to complete two dozen games (and hence improve my game).
My questions
So is it a good idea

to play faster time controls too (online),

or to increase the number of simultaneous correspondence chess games I play?

If the second course of action is better, how many games should I (optimally) play simultaneously to increase my performance?
If the first is better, what time control is the most suited to my need?
Note
Information that could be of some use to potential answerers.

I've heard that Blitz and Bullet chess aren't really good for learners.

My rating was between 1200 and 1300 in the rapid time control on Chess.com (before my data got erased).

My training (puzzles) reading online Lichess reached 1903 before falling to 1842, after which I've been inactive for quite a while.

Correspondence chess will do more to improve the quality of your game. That is, your moves will be a lot more thoughtful and deliberate, and so will your opponent's. When you lose, it will probably be due to a subtle mistake beyond your ordinary comprehension (have better players point out where and why you lost).

That said, "fast" games may do more to improve your playing strength. There will be times when you will "under the gun" and make "stupid" mistakes under time pressure. In the short run, at least, minimizing such mistakes will do more to improve your rating.


Can all UCI engines output a FEN for the current position or is it just StockFish? I know in StockFish if you type "d" you get an ascii view of the board and a FEN string for the current state. Is there any command in other UCI engines such as Rybka 4 that will output a FEN string?

From reading various chess source codes, mostly before 2005, I can state that most don't a FEN output.  Any that would allow for a non-starting position should accept FEN, as it's just a special form of PGN.
Crafty and san_kit both have a "fen" command.


Chess Annotation Software I frequently use chess.com to self-analyze and annotate my games. Although it has a useful feature to save my annotated game as a url (which I then save as a bookmark), I'd rather switch to local software so that I may organize and backup my collection.

I have tried a couple of engine-oriented programs like Shredder and Stockfish for mac, but they don't really fit my needs.

I generally just need software where I can import a pgn (or setup a position), make moves on both sides of the board, add annotations, and add move variations. And that's pretty much it. It would also be nice to be able to categorize my games for easier access.

I don't need a chess engine or any computer-assisted analysis, although I understand that those would probably be bundled with most chess software.

Can anyone provide any suggestions that might fit all or some of this criteria? Any help would be appreciated!

I agree with @InertialIgnorance Chessbase is very useful and good. I have also used chess database software which have the advantage of being free:

Scid ("Shane's Chess Information Database") is a free and open source UNIX, Windows, Linux, and Mac application for viewing and maintaining huge databases of chess games
Scidb,  is a free chess database application for Linux/Unix and Windows. Scidb is inspired by Scid but it is a completely new development.


Chess Logic - Tigran Petrosian's doctoral dissertation I have recently learned that former chess world champion Tigran Petrosian earned a PhD title from Yerevan State University; the title of his dissertation title was Chess Logic.

I would like to read what he wrote. I can read Russian. Any idea how to get hold of this text?

EDIT: I have just read in a chess history book that between his two matches with Spassky, Petrosian worked on the philosophy of the chess battle, studied the secrets of the process of chess thinking, successfully defended a dissertation on this subject and became a candidate of philosophical sciences - my translation from Russian. This cryptic text does not mention the title of doctor (PhD) but an obscure title of candidate.

According to WorldCat.org, Tigran Petrosian's PhD thesis is available in three libraries: the Koninklijke Bibliotheek ("royal library") in The Hague (Netherlands), the Danish Union Catalogue and Danish National Bibliography (a catalogue strangely identified as a "library"?) and the State and University Library in Denmark.

Apparently, the English translation is (or was) only available in 250 copies, so there may be other libraries that have it but that aren't covered by WorldCat.org. Once you've identified a library that has it, you can try to get a copy through interlibrary loan. (This may work best if you have access to a university library, especially for international interlibrary loan.) The other option is trying to buy it through a website for second-hand books, but the book is so rare that your chances of finding it are very small.

See:

Tigran Vartani Petrosjan: Chess Logic. Skakhus-forlaget, 1968. Translated from the Russian into English by Carl Andersen. (See the catalogue entry at the Koninklijke Bibliotheek.)
Tigran Vartani Petrosjan: Skak logik. Copenhagen : Skakhus, 1968. Translated into Danish by Carl Andersen. (See the catalogue entry at the Koninklijke Bibliotheek.)


Is it possible Alpha Zero will eventually solve chess? I googled this question and ended up here. From previous questions, it seems Alpha Zero has not solved chess yet and if it does it will take a very long time. Nonetheless, it may be possible one day. I am wondering whether the programmers, or whichever title designers of the Alpha Zero system prefer to use, have built anything into Alpha Zero to detect if it discovers a solution. Also, even though the time required to solve chess is clearly enormous, even with the power of Alpha Zero has anyone attempted to calculate how long it might actually take? Is it likely to be more or less than 7.5 million years and is it possible it will involve the number 42? Perhaps all chess games can always be concluded in 42 moves with perfect play.

No, it can't.
Even if you had it train on a zillion self-playing games and it miraculously achieved perfect play somehow, we would have no way of proving that it had achieved perfect play without first solving chess some other way and then comparing AlphaZero's play to perfect play in all possible positions.
Its approach simply doesn't result in a solution for chess, it's just a way to find good moves. A solution is a mathematical proof.


Professional Databases and Historical Games I have tried to look for historical chess games (i.e. 19th century to early 20th century). I usually use Chessbase online database and chessgames.com.

I have never paid for a database or database subscription, but I was wondering if anyone knows whether they tend to have more complete historical games than the free options available on these chess websites?

Have you looked at https://chess-db.com/public/index.jsp

This website has historical players like: Morphy, Marshall, Steinitz, Bird. You can download all their games.


Why should I expect that black moves Rxd2 after I move Bxe3 in this puzzle? I've been playing a few puzzles for a couple of days, and I see that often the final move to chessmate is easy to spot, but earlier moves aren't (to me).
In this case, for instance, why should I expect black to defend the king with the rook, rather than, say, eating it with the queen?
4rk2/1bq2p1Q/3p1bp1/1p1n2N1/4PB2/2Pp3P/1P1N4/4RK1 w - - 0 2

1. Bxd6 Re7 2. Qxf7

The point here is that none of Black's possible responses to 1. Bxd6 prevent 2. Qxf7#. Blocking with the rook or queen leaves it pinned, and blocking with the knight or bishop or capturing with the queen means that the black queen is no longer attacking f7. The puzzle just gives an example second move, with the implication that it doesn't matter which one they pick. (The fact that this example involves a pin makes 2. Qxf7 a little bit less obvious, so that's probably the motivation for that choice.)


Countering The Wayward Queen Attack I'm a new player =I just started playing again after an over 10 year hiatus. I'm (sadly) in the 600s.
I've been studying openings and I seem to do better in games where I can use the Italian game or Ruy Lopez. However, there's a strange game that I continually lose a slow and painful game against and it's the family of plays that have the queen out causing havoc early. In particular, the [Wayward Queen Attack][1] has been at the heart of every game I've lost in the last 3 days.
I mostly contribute this to my lack of piece development out of fear of losing pieces to a queen. How should I counter it?
[1]: https://en.wikipedia.org/wiki/Wayward_Queen_Attack "The Wayward Queen Attack"

First of all, despite the stigma attached to early queen moves Nakamura has played the white side of 1. e4 e5 2. Qh5 several times in top level play, so it is a move you should treat with respect.
The best approach is probably to play moves like 2... Nc6 to protect the e pawn, 3... g6 to kick away the queen, then Nf6, Bg7, castles to get your king safe. Then if the white queen is still in the middle of the board try and attack it with your pieces.
Then you are in a normal game and if you blunder pieces because of your low rating then consider that your low rating is probably because of your poor tactical ability. To correct this you need to work on tactics. Learn about pins, forks, skewers, discovered attacks, etc. and do lots of puzzles to try and improve.


What are some non-functional features of a chess clock that would help choose the best for ones use? All chess clocks time the match. Some just time, some add delays, some add on, and other have variations for TIMING.

What else might be a factor in deciding to buy a clock that is primarily for personal use at speed chess in a club, cafe, or park,  but also useful should one play in tournaments? For examples, cost,  reliability, and ease of use are some factors. What would be the features that would help guide a purchase?

There might be other subtler ones, so a complete list for consideration is what is asked for.  Comments on why would be useful too.  EG what value does some certification add, if any.

I am thinking there could be easily a dozen or more of these NON-FUNCTIONAL characteristics.

Well I learned way more than I wanted to know about other considerations than mere timing.

This table may be collapsed into a long string of text
someone please edit if that happens

Cost
Size
Accuracy
Precision
Ease of use
Color
Battery Life
Reliability
Ruggedness
Toggle method
maintenance required
Flag display
Analog/digital
Shape
Aesthetic
Ease of setting
Read out type
Safety against accidental reset
Counts moves
Useful for other than chess

Timing variations
 - pre/post add
 - pre/post delay
 - fischer
 - bronstein
 - hourglass - seesaw
 - byo-yomi
 - canadian OT
 - guillotine
 - bonus timing
 - different periods timings

custom settings -MODIFY built in
custom settings NEW
Number of custom settings


How do you manually set switches when you are compiling Stockfish in Visual Studio? How do you manually set switches when you are compiling Stockfish in Visual Studio?

In the type.h file it saids:

  When Makefile is not used (e.g. with Microsoft Visual Studio) some switches
  need to be set manually:

  -DNDEBUG      | Disable debugging mode. Always use this for release.

  -DNO_PREFETCH | Disable use of prefetch asm-instruction. You may need this to
                | run on some very old machines.

  DUSE_POPCNT  | Add runtime support for use of popcnt asm-instruction. Works
               | only in 64-bit mode and requires hardware with popcnt support.

  -DUSE_PEXT    | Add runtime support for use of pext asm-instruction. Works
                | only in 64-bit mode and requires hardware with pext support.

I just want to where where/how do you put these "commands"?

This question should be in programming.

These can be put in a top h file, the best being stdafx.h.  Just include "#define DNDEBUG",

They can be added to the command line/compiler commands.  Under VS6, Project->Settings (Alt+f7), there is a box to add project settings under the c/c++ tab.


Implementing Late Move Reduction (LMR) inside iterative deepening Here I am trying to improve my engine, and the next feature on the list is LMR.
I understood the general ideia, but since I don't want to introduce bugs and the CPW on the subject has no code, how do I go about coding it inside an iterative deepening scheme?
Here's my current code:
   //inside alpha-beta move loop
   //bool doReduce = false;
   int tmp_mv = moves.get(i);

 /* Late move reduction CPW code */
    if (depth > 3 && legal > 3 && (!atCheck) &&
        Move::captured(tmp_mv) == 0 && Move::promoteTo(tmp_mv) == 0 &&
            (mv_from != Move::from(board.searchKillers[0][board.ply]) || mv_to != Move::to(board.searchKillers[0][board.ply])) &&
            (mv_from != Move::from(board.searchKillers[1][board.ply]) || mv_to != Move::to(board.searchKillers[1][board.ply])) &&
            !oppAtCheck){
                int reduce = legal > 6 ? 2 : 1;
                //doReduce = true;
                score = -alphaBeta(-beta, -alpha, depth - 1 - reduce, true);

            //re-search
            if (score > alpha)
               score = -alphaBeta(-beta, -alpha, depth - 1, true);
        }
        else {//no LMR
            score = -alphaBeta(-beta, -alpha, depth - 1, true);
        }

This appears to be working, but I have some questions:

Is the code correct?

CPW engine (and many others) have code like this:
 if (! isPV && ... ) { apply some heuristic }

Since I'm not using PVS, how do I deal with this in my code? Do I need something like this:
//probe hashtable, at the top of alphabeta
int hash_move = HashTable::probe(board)

//inside move loop
if (tmp_mv !=  hash_move && conditions ){ apply heuristic }

Thank you!

LMR is a general technique and there is no rule on the best implementation. That is why chess programming is hard, because you are expected to come up with your own interpretation and implementation.
LMR works like this:

if (this is a late move)
{
    if (this late move satisfies certain conditions)
    {
        Find a reduced depth to search
        Search alpha-beta with the reduced depth
        Do a full-search if the result is greater than alpha
    }
}

LMR is easy to understand but hard to master. Let's go through one by one. We will use Stockfish for our example. The code is https://github.com/official-stockfish/Stockfish/blob/master/src/search.cpp.

If this is a late move. What is a late move? We know the first move in iterative deepening is definitely not a late move, because we assume the first move is most likely the best move. Stockfish defines a late move like this:

if (... moveCount > 1 ...)

Stockfish starts LMR search if there's enough  depth to reduce and the move is not the first move in iterative deepening (moveCount > 1). There is no right or wrong answer here, in my engine I refused to reduce for the first two moves and I like my idea. Your implementation might be different, but you should always find a move that you think most likely to fail-low. The CPW wiki suggests:

  Typically, most schemes search the first few moves (say 3-4) at full
  depth, then if no move fails high, many of the remaining moves are
  reduced in search depth.

This is just a recommendation, as Stockfish has implemented more aggressive reduction.

This late move satisfies certain conditions. Generally, you don't reduce if:

Tactical sequences
Checks
During reduced search
PV node

You should consider to minmise reduction for PV nodes. The PV nodes form the most likely sequence of moves your engine reports, thus it's important to be as precise as possible.

You should also be careful if the move is a capture, because it's easier to make a search horizon mistake if you reduce the move too much.

This is Stockfish's implementation:

if (    depth >= 3 * ONE_PLY &&  moveCount > 1
  && (!captureOrPromotion || moveCountPruning))

Find a reduced depth to search. This is hard because nobody knows how much to reduce. You'll need to play hundreds and hundreds of games to tune your parameter. Generally, you reduce more if:

Cut node
Poor SEE
Quiet move

Again, there's no right or wrong here. Stockfish has the following:

 // Decrease/increase reduction for moves with a good/bad history
 r = std::max(DEPTH_ZERO, (r / ONE_PLY - ss->history / 20000) * ONE_PLY);

 if (cutNode)
     r += 2 * ONE_PLY;

 // Decrease reduction for moves that escape a capture. Filter out
 // castling moves, because they are coded as "king captures rook" and
 // hence break make_move().
 else if (   type_of(move) == NORMAL
             && type_of(pos.piece_on(to_sq(move))) != PAWN
             && !pos.see_ge(make_move(to_sq(move), from_sq(move)),  VALUE_ZERO))
      r -= 2 * ONE_PLY;

Stockfish considers the history, node type and move type.

Search alpha-beta with the reduced depth. This is standard. You will need to recursively search for the reduced depth you calculate. Stockfish has this:

  value = -search(pos, ss+1, -(alpha+1), -alpha, d, true);

Note that the reduced depth is passed to the search function.

Do a full-search. This is also standard. If your alpha-beta returns something greater than your lower bound (alpha), you have no choice but to do a full-search. If your LMR implementation is correct, the benefit you gain by reducing should outweight the cost of doing a full-search. Otherwise, LMR is a liability. Stockfish has this:

// For PV nodes only, do a full PV search on the first move or after a fail
// high (in the latter case search only if value < beta), otherwise let the
// parent node fail low with value <= alpha and try another move.
if (PvNode && (moveCount == 1 || (value > alpha && (rootNode || value < beta))))

EDIT:

You don't have to add a check to PV node if you don't want to. But in chess programming, there are lots of things you should and should not be done in PV nodes. For example, we typically don't reduce for PV nodes. Your engine might lose rating if you don't check.


Non-losing strategy for white If you modify chess so that white gets to make one extra move within the first 10 moves, is it possible to show there is a non-losing strategy for white?

Student T gives an explicit answer, but you can also view it from a game-theoretical perspective.

Suppose normal chess is a draw (or a win for black). Then, white can play 1. Ng1-f3 and Nf3-g1, effectively becoming black and the rest of the game is normal, so it is a draw (or a win for white).

Suppose normal chess is a win for white. This will almost certainly involve moving a pawn two steps from its initial position within the first 10 moves, or moving a bishop, queen, rook or king. You can use your extra move to perform this move in two steps, e.g. e2-e3-e4 or Bf1-d3-e2.

In any case, White will not lose the game.


Why is the time control for FIDE chess tournaments what it is? Now that from this answer, I know what the time control is, why is it 90 minute base time for the first 40 moves, an additional 30 minute base time for the rest of the game plus a 30 second increment for each move, and not a 2 hour base time with 30 second increments per move? It doesn't seem to make any sense. If the directors already have time to stay more than 4 hours and 41 minutes after the tournament begins, the maximum amount of time that could go by before the 41st move is completed, why are they rushing them to complete the 40th move a whole hour before then? They would still have the same amount of time to complete the 41st move if it was a 2 hour base time and 30 second increments. Are they specifically trying to rate them on their ability to play with that time control so that they'll know that the ones with a really high rating know how to adapt to playing well with that time control?

We can't really answer what all the reasons for the decisions were, as there are many people involved with the committee that decides on the FIDE time controls and they haven't published their reasoning.

So I just want to point out two things:

One, history. A slightly older time control are for instance 2 hours for the first 40 moves, then 1 hour for the next 20 moves, then 30 minutes for the rest of the game. Before that, games were adjourned after move 60. Earlier time controls were similar but with more time per move. So there is a long tradition of time controls for parts of the game and not for a long time period for the whole game.

The reason is that organizers want to ensure that players have sufficient time left in each period of the game. As players don't know in advance whether their game will last 35 moves or 115, it's hard to decide how much time to use on the first 30 moves. A player who wants to have sufficient time left to play the endgame well has a middle game disadvantage against a player who just burns all his time assuming he doesn't reach that point. We want players to be able to play all parts of the game well so we add the time only if it is needed.

Another thing is to save time in case the game is short. Someone on the losing side of a game is going to use all his time to try to save it, so short games would take very long if all that time was given at the start. Tournaments are already very exhausting.


Is it true that a good "flanker" (flanking position) is worth more than a pawn? If so, why? Perhaps I've used the wrong term, but I'll describe what a "flanker" is.

In the Queen's Gambit, there is often the possibility for White to sacrifice a bishop on h7.

1.Bxh7+ Kxh7 2.Ng5+ Kg8 3.Qh5 Kf8 (the rook is on e8) 4.Qh8+ Ke7 5.Qxg7 (taking the g pawn.) White has two pawns for a piece, is down a third "pawn" and usually has the advantage. Why is that?

Some observations:

1 White has a passed h pawn that is a queening threat in the end game, and possibly even in the middle game.
2 White dominates the g and h files, where Black pieces have no safe haven. It is this domination of two "edge" files that make for the "flanker." Black is confined to six files.
3 Derivative from b) White controls at least eight squares on Black's side of the board. If Black has nothing beyond the fourth rank on the a-f files, he is limited to 24 out of 64 squares.

This effect is so strong that it even extends to positions that I would classify as "quasi flanker".

For instance, in this "Immortal Zugzwang game, Black sacrificed a knight for two pawns so that his rooks on the f file act as a "flanker" against White's whole queen side:

http://en.wikipedia.org/wiki/Immortal_Zugzwang_Game

[FEN ""]
1. d4 Nf6 2. c4 e6 3. Nf3 b6 4. g3 Bb7 5. Bg2 Be7 6. Nc3 O-O 7. O-O d5 8. Ne5 c6 9. cxd5?! cxd5 10. Bf4 a6 11. Rc1 b5 12. Qb3 Nc6 13. Nxc6 Bxc6 14. h3? Qd7 15. Kh2 Nh5 16. Bd2 f5! 17. Qd1 b4! 18. Nb1 Bb5 19. Rg1 Bd6 20. e4 fxe4! 21. Qxh5 Rxf2 22. Qg5 Raf8 23. Kh1 R8f5 24. Qe3 Bd3 25. Rce1 h6!! 0–1

And in this 1919 game between Capablanca and Yates, White sacrifices a rook for the light squared bishop and a pawn between moves 22-24, and comes away with a "quasi flanker" on the queen side (and a winning advantage).

http://www.chessgames.com/perl/chessgame?gid=1055968

[FEN ""]
    [FEN ""]
1. e4 e5 2. Nf3 Nc6 3. Bb5 a6 4. Ba4 Nf6 5. O-O Be7 6. Re1 b5 7. Bb3 d6 8. c3 Na5 9. Bc2 c5 10. d4 Qc7 11. Nbd2 Bg4 12. d5 g5 13. Nf1 h6 14. Ng3 Rd8 15. a4 b4 16. cxb4 cxb4 17. Bd3 Bc8 18. Be3 Ng4 19. Rc1 Qb8 20. Bd2 Qb6 21. Qe2 Nb3 22. Rc6 Qa5 23. Bxa6 Bd7 24. Bb5 Bxc6 25. Bxc6+ Kf8 26. Qc4 Nxd2 27. Nxd2 Qa7 28. Qe2 h5 29. Nf5 Bf6 30. Nc4 Qc5 31. b3 Nh6 32. Nxh6 Rxh6 33. Qe3 Rc8 34. Rc1 Bd8 35. Qxc5 dxc5 36. Nxe5 Ke7 37. Rxc5 f5 38. Rc4 Ba5 39. Bb5 Rxc4 40. Nxc4 Bc7 41. e5 Bb8 42. Ne3 Rh7 43. Nxf5+ Kf7 44. e6+ Kf6 45. e7 Rxe7 46. Nxe7 Kxe7 47. g3 Bc7 48. Kg2 Kd6 49. Be8 h4 50. Bf7 Ke5 51. Kh3 Bd8 52. Kg4 hxg3 53. fxg3 Kf6 54. Be6 Kg6 55. d6 Kf6 56. Bf5 Bb6 57. d7 Bd8 58. h4 gxh4 59. gxh4 Bc7 60. h5 Kg7 61. Be4 1-0

What compensation did the winners get for their sacrifices?

I will give you my view, though I'm only a FIDE 2200 player. Such rules do not apply in all games and you usually should not let them affect the game. That does not mean that all rules you hear are not valid, for example take the first example: a sacrifice of a piece for two pawns and attack on the king is usually good compensation. But it always depends on the position, it is up to the player to determine the strength of the attack. I would go with the known rules using them carefully. All rules have exceptions.

Compensation in the Nimzowitch game is perhaps the hardest to explain, I would guess that he saw the end position before the sacrifice since he was great tactical player.

In the Capablanca game the compensation is more clear, a bishop, a protected passed a-pawn and white square dominance and it is true that black is so badly coordinated that he cannot effectively use his kingside flank.

To the original question, it is always some advantage that compensates for a pawn and yes, it could be control on some part or side of the board. It is always up to you to determine the extent of the advantage. Your observation no.3, though: there are openings where black is confined to little space but gains a flexible position so space advantage alone is usually not compensation in itself.


Seeking a particular problem I recall seeing a problem in Games magazine, probably in the early 1990s, that required the solver to deduce that a capture en passant was possible (not just because that's the only way to get a solution, but using retrograde analysis). I recall that all the pieces (including pawns) on the board were congregated in one corner — if I recall correctly they were all in the first three files and the last four ranks. The solver was required to mate in a small number of moves, possibly two. Does anyone know what problem it is?

I found a problem that perfectly fits your description! I’ve played the position back a move for the double step.
[Title "Kurt Keller, Stuttgarter Nachrichten & Südwest Presse (Ulm) 1993, Mate In Three"]
[FEN "5RbN/5ppk/5P1P/5P1K/8/8/8/8 b - - 0 1"]
[startply "2"]
[startflipped ""]

1... g5 {Now White mates in three.} 2. fxg6+! fxg6+ (2... Kxh8 3. gxf7 Kh7 4. fxg8=Q#) 3. Nxg6 Bf7 4. Rh8#

If the Games magazine flipped the position, then this is a problem with all pieces in one corner, on the first three files and last four ranks, a short number of moves, and an en passant key! Even it wasn’t flipped, your mind might have altered your memory. Since the problem itself is from the early 1990’s, it’s safe to to assume that the Games magazinre reprinted it for show.


How many unique pawn structures are possible? In an effort to classify chess games, I thought it would be useful to identify a set of positions by their unique pawn structure that would form a family of positions. There are indeed many positions but my rough calculations indicate 10^12 to be a upper limit of all possible combinations (I may be very wrong as I don't trust my calculations). But interestingly, it is way lower than the number of sensible position,s i.e. ~10^46. I am very interested to know the actual number of pawn structures (mwithout promotion). I guess actual number of legal positions would be difficult to estimate but a general idea might be good.

To classify pawn formations, a good source is chess master books that explore that topic. The book by Boris Persits comes to mind, for example.
I add that it seems impractical as you have been told, to make an exhaustive index of all the combinations that pawn chains can take.
However, it is useful to connect families of openings (classified by ECO, or by open / closed / flank, positional or tactical) and also by the types of endings that can be found according to the pawn structure.
This information has didactic utility for chess plans. There are books that touch on the subject of pawn structures and chess plans.
The pawn chain structures could be described with the characteristics: doubled or solitary / past / advanced / delayed / blocked pawns, V chain or inverted V chain, castling with / without fiancheto and other descriptors that I cannot imagine.
In this way, the number of pawn formations is much less than combinatorial theory can estimate.


How likely is it that a non-orthodox promotion is optimal? Underpromotion is an interesting aspect of chess, but there are other possibilities that aren't allowed under modern rules.

One is the so called "dummy pawn" as this question discusses:
When (if ever) was it a rule that pawn promotion was optional? where the goal would be to stalemate oneself.

Another is promoting the pawn to a piece of the opposite color, where the goal could be to smother the enemy king with one of his "own" pieces, as in the Wikipedia example, or perhaps to cause one's own king to be stalemated with the help of the newly created enemy piece.

If both of these were allowed, promoting to a weak enemy piece would often serve the same purpose as a dummy pawn, so in such cases, suppose the dummy pawn is our default, if it works.

Which of these situations would be less likely to occur? Would either of them be more likely to occur than underpromotion to a rook, bishop, or a knight?

Thanks for your great question. Here's what I think about the relative frequency of different joke promotions, in games and compositions. Many such compositions are helpmates or selfmates, but the rationale for promotion choice is already a bit peculiar in those, so in this topic we'll focus on games, direct mates or studies.
Regular promotions
First, a quick review of the frequency of legal promotions, as quoted in the Wikipedia page you pointed at:

Piece      %
Queen  96.9
Knight  1.8
Rook    1.1
Bishop  0.2

Couple of points:
(1) A knight promotion is arguably not an under-promotion, in that the promoted piece gets immediate access to squares that the queen does not. The most common use of a knight promotion is in hot positions where a tempo is key.
(2) Rook and bishop are definite under-promotions: they may be used to turn a draw into a win by avoiding stalemating the opponent. But they might also be used (more in compositions than in real life) to turn a loss into a draw by entering a block position.
(3) I doubt that the need for a bishop promotion is as high as 0.2%. There are certainly cases where it is the answer, but I suspect that these are dwarfed by those where B under-promotion was selected for fun. I have certainly seen GM Hikaru Nakamura do this for grins against computers.
The Dummy Pawn
The dummy pawn takes the idea of under-promotion to its logical extreme. In principle, it would mainly be used in games to turn a lost position into a draw, since (unlike bishop or rook) it doesn't rely on other pieces to be blocked. But positions have also been constructed where the dummy pawn can turn a draw into a win. Here, the defensive player would have two alternative lines, one drawing against a bishop, the other to draw against a rook. For all the drama, I don't know of any tournament where the dummy pawn rule of 1862 was actually played. There are some good compositions though, but returning to the frequency comparison, dummy pawn would come in at approximately 0.0%!
Enemy unit
Moving on to promotions to enemy unit. There are numerous 19th century joke promotion problems relying on promotion to enemy officer. According to chess historian Mario Richter, one influence here was Bilguer's Handbuch des Schachspiels, which was for many generations of chess players the reference work on chess. Especially it refers to the paragraph defining the rule of promotion:

Gelangt [der Bauer] auf die letzte Reihe des Brettes, auf welcher anfangs die Offiziere des Gegners stehen, so muß der Besitzer ihn augenblicklich umwandeln und zu einem beliebigen Offizier machen. Hierbei kann man eine zweite Dame, einen dritten Springer u.s.w. wählen; nur versteht es sich, daß der Bauer nicht in einen zweiten König verwandelt werden darf.
(If the pawn reaches the last rank, which is occupied in the starting position by the enemy officers, it has to be immediately promoted to an arbitrary officer. In this way you can have a second queen, a third knight etc, but you cannot have a second king.)

So Bilguer forgot to specify that the promoted officer should have the same colour as the pawn!
There are many joke compositions involving promotion to enemy knight, bishop or rook. If one was looking for their movement capabilities, then these might be replaced by a  friendly dummy pawn instead, which cannot move at all. However, an enemy unit is that it cannot be captured by another enemy unit, in particular it blocks a flight square for the king. It can also serve to prevent stalemating the opponent, by giving him a new piece to move around.
It is normally assumed that promotion to enemy rook can be followed by castling.
So in summary, I think the enemy officer is less useful than friendly dummy pawn for getting one's self stalemated, and more useful for avoiding stalemating the opponent. The relative frequencies would reflect this, approx 0.0% again.
Open Cases
There are two open cases where I know of no existing compositions:
(1) Promotion to enemy queen. How could it be in my interest to promote a pawn to enemy queen rather than enemy rook or bishop?
(2) Promotion to enemy pawn. This would require a new rule: how does a pawn on first row move? And by analogy with the rook, can it double-step?
(Promotions to king, white or black are also found in problems, but let's follow Bilguer to exclude them from scope because the field of discussion here is already broad enough, and they would require an extension to the rules concerning how checkmate works against multiple kings.)


Improving your position? A recommendation from IM Andrew Martin was to improve the position of your worst piece if you are not sure what move to make.  Are there any other ways one could improve their position besides the above recommendation?  I often find myself making useless moves, that mostly turn into blunders because I am not sure what to do in the position.  Sometimes this is a result of just thinking too hard and over-complicating things.

Here is a real-life sample that IM Andrew Martin used to express his point. In the 2007 British Championship between between Nicholas Pert (White) and Stewart Haslinger (Black), which can be found here, after 9. Re1, White showed what his plan was going to be and that was to play e4, which he did on move 10.  After 9...Be7 10. Re1, IM Andrew Martin says we reached a critical point in the game which Haslinger got wrong and that was to improve the position of his worst posted piece, which is his Knight on b8. Why? Because it is blocking his Rook on a8 and without the participation of the Rooks, black is not going to be in very good shape. White is going to dominate the center with e4 to e5. Instead of improving the position of the b8 Knight, Haslinger played 10...O-O. IM Andrew Martin instead suggests Black should have taken some pieces of e4 via:  10...Nxe4 11. Nxe4 dxe4 12. Bxe4 Bxe4 13. Rxe4 Nd7.  His reasoning was that, Black has now improved the position of his Knight, he is not as cramped as before, he can castle in peace, and White has no pawn breaks to upset the position.  Here is the complete game:

[FEN ""]
1. d4 d5 2. c4 c6 3. Nf3 Nf6 4. e3 a6 5. Nbd2 Bf5 6. Qb3 Qc7 7. Bd3 Bg6 8. O-O e6 9. Re1 Be7 10. e4 O-O 11. e5 Nfd7 12. Bxg6 hxg6 13. Nf1 Re8 14. Bg5 Bf8 15. Rac1 Qb6 16. Qc2 dxc4 17. Ne3 c5 18. d5 exd5 19. Nxd5 Qc6 20. Nf4 a5 21. e6 fxe6 22. Qxg6 Na6 23. Bd8 e5 24. Qxe8 Nc7 25. Qh5 exf4 26. Ng5

Improving your worst piece is indeed generally a great thing to do if it's not a bad idea for tactical reasons. Some other standard general ways to improve your position:

Develop all of your pieces.
Occupy an open file with a rook (or queen). Bonus: double or triple your pieces on this file.
If you already have occupied an open file with a rook, move it to your seventh rank if possible.
Put your rook opposite the enemy queen.
Connect your rooks (get the other pieces out of the way so they're defending each other).
Castle.
Make sure you can't get mated on the back rank.
Make sure you don't have any undefended pieces (even if they're not attacked).
Defend an important pawn or square more than once (known as overprotection).
In the endgame, centralize your king.

Of course, tactical opportunities (for you or your opponent) trump these considerations, but all of these are general principles for improving your position in such a way that tactical opportunities are likely to turn out in your favor in the future. For example, putting your rook opposite the opponent's queen means that he has to worry about some situations in which the pieces in between move.


Was there ever a time when the goal in chess was to capture the king? The modern rules of chess, except for the stalemating being a draw, are basically equivalent to a game in which the goal is just to capture the king, not checkmate him. It's plausible that in the oldest versions of chess, this was indeed the goal, but since a rational player would then always move their king when in check, and never leave themselves in check, and would only have their king captured when there was no escaping from it, players may have decided that responding to check may as well just be made a rule.

I haven't been able to find any reliable source either confirming or refuting this hypothesis. Is there any?

Wikipedia claims that

  In early Sanskrit chess (c. 500–700) the king could be captured and this ended the game. The Persians (c. 700–800) introduced the idea of warning that the king was under attack (announcing check in modern terminology). This was done to avoid the early and accidental end of a game. Later the Persians added the additional rule that a king could not be moved into check or left in check. As a result, the king could not be captured,[13] and checkmate was the only decisive way of ending a game.[14]

References [13] and [14] are to Davidson, Henry (1949), A Short History of Chess, which can be consulted on Google Books. I couldn't tell immediately what sources Davidson used.


What programs (preferably open source) offer play against a computer with fine-grained difficulty-related adjustments? My last serious attempt to get into chess ran into a basic difficulty with the program: with a bit of work, I got to a point where I could beat difficulty 1 or 2 on a scale of 10, but got consistently clobbered when I took on difficulty 3. I have subsequently looked, but not found, chess programs where I can normally find a difficulty that lets me win, say, 40%-60% of the time, and this remains true when I incrementally learn to improve my game.

What, if any, chess engines out there offer finer gradations in the level of difficulty? It would be nice to have engines that offer more than one realistic way of offering an easier opponent. And ideally make mistakes that would make actual sense as an understandable mistake in a game of chess, not arbitrarily weakening the opponent by e.g. having a 1 out of n chance of making a random legal move.

Thanks,

My favorite program for this is Chess Tiger Pro This is a paid app.

You can set difficulty in 50 elo point increments.  Some programs, such as shredder, allow you to set exact rating number.  I like Chess Tiger Pro because it seems to play poorly better than other programs.  I mean more human like mistakes.


Chess games that advanced endgame theory Single games of chess can routinely have a significant impact on opening theory, of course, but it should be quite uncommon for a single game to significantly advance endgame theory, since that's a phase of the game where we can and do have some absolute knowledge that will never change, and since the chance combination of a situation that is ripe for something fundamentally new to be discovered along with a player capable of doing the discovering in the course of a game is a rare thing.

Nevertheless:

  I am looking for pointers to historical instances where the course of a game's play revealed new theoretical endgame knowledge that was unknown before that game was played, e.g. an unknown winning method in a certain type of endgame, or an unexpected drawing resource that had escaped notice until that point.

In a game at the 1954 Olympiad in Amsterdam, Botvinnik had the white pieces against Nikolay Minev of Bulgaria, and reached the following position after 57. Qxe6:

[FEN "8/8/4Q3/k6K/8/6P1/8/q7 w - - 0 1"]
[StartFlipped "0"]

In Half a Century of Chess, Botvinnik writes,

  Ten years prior to this game I had such an ending against G. Ravinsky ... There I did not understand the specific character of the ending and I tried, as in a rook ending, to keep my king on the eighth rank to support the promotion of the pawn at g8 and, this made the win most difficult.

That earlier game against Ravinsky had been analyzed by Keres, but still little had been properly understood about this ending. For instance, in a note after 61. ... Ka4 in the Minev game, Botvinnik points out, "Minev willingly occupies a4 with his king, as this was recommended by Keres in a well-known article where he analysed the ending of my game with Ravinsky." Instead, it turns out that the best place for the black king in this situation would have been the corner a1 square. There was an adjournment at move 73, and Botvinnik notes,

  Although I did not find the correct plan before the adjournment, nevertheless I instinctively avoided moving my king to the eighth rank. After thorough analysis I finally found the right way of playing this ending. ... The winning plan consists in placing the white king on the same rank (or file) as the black king, or on the adjacent one. In this case White has a good chance of sheltering his king from checks. Once the method is found, of course, it looks simple.

Finally, after White's 91st move, Botvinnik's plan had reached fruition:

[FEN "8/6P1/8/2KQ4/k7/8/7q/8 w - - 0 1"]
[StartFlipped "0"]

  Black has as many as three checks, but they all lead to the exchange of queens. Here the game ended, Black resigned, but the first page of genuine theory was opened on the ending "queen and pawn against queen".

For yet another source commenting on the ending to this particular game,
here is Giddins in his The Greatest Ever Chess Endgames:

  Relatively little was known about this type of endgame at the time this game was played, and despite a few inaccuracies in the play, Botvinnik first demonstrated the winning method for such an ending in this game. ... Without the aid of either tablebases or any substantial theoretical practice, apart from his own game against Ravinsky years before, Botvinnik effectively "solved" this ending in his adjournment analysis, identifying all the key elements of the winning method in such positions.


Who wins in the game "knight" if both players play optimal? The rules of "knight" : Player 1 puts a knight on some square. Then the players,
 beginning with Player 2, alternately move the knight. The knight cannot be
 moved to a square already visited, including the starting square. The player,
 who cannot move the knight anymore, loses.

Which player has a winning strategy ?

In my answer to the same question over on math.stackexchange, I discussed general m by n boards. Here I will just give a winning strategy for Player 2 on the ordinary 8 by 8 chessboard. It's based on the following pairing of squares:

a1c2, b1d2, c1a2, d1b2, e1g2, f1h2, g1e2, h1f2,
a3c4, b3d4, c3a4, d3b4, e3g4, f3h4, g3e4, h3f4,
a5c6, b5d6, c5a6, d5b6, e5g6, f5h6, g5e6, h5f6,
a7c8, b7d8, c7a8, d7b8, e7g8, f7h8, g7e8, h7f8.

That is, square a1 is paired with square c2, b1 is paired with d2, and so on. Note that the 64 squares are partitioned into nonoverlapping pairs, and each set of paired squares are a knight's move apart. The winning strategy for Player 2 is: WHEREVER PLAYER 1 PUTS THE KNIGHT, MOVE IT TO THE OTHER SQUARE IN THE SAME PAIR. For instance, if Player 1 starts the game by dropping the knight on e8, Player 2 replies by playing Ng7. If Player 1 now plays Ne6, Player 2 plays Ng5, and so on. Here is a sample game, with Player 1 making random moves, and Player 2 following the winning strategy described above:

Ne8 Ng7 2. Ne6 Ng5 3. Nf3 Nh4 4. Nf5 Nh6 5. Nf7 Nh8 6. Ng6 Ne5 7. Nc6 Na5 8. Nb3 Nd4 9. Ne2 Ng1 10. Nh3 Nf4 11. Nh5 Nf6 12. Ng4 Ne3 13. Nc5 Na3 14. Nb1 Nd2 15. Nf1 Nh2 and Player 2 wins.

P.S. Of course the strategy still works if White is allowed to move the knight to any square not already visited, and only Black is limited to making knight moves.


What factors define changing popularity of different Openings over time? Recently I found some rather interesting graph displaying how popularity of different openings changed over time.

Image courtesy of; see also fullsize there

As far as I understand, new researches over classic openings may unveil some hidden treasures or vulnerabilities, but I can't figure out why changes were so drastic. For a comparison, in Physics, different approaches in Theory of Relativity also take place, but sooner or later more and more scientists group around three or so major approaches.

Furthermore, with today's progress in computational methods, strengths and weaknesses of each opening can be formally (not statistically) proven. Instead, what we are seeing here, "Other" openings take kind of 40% and growing on recent years.

So, my question is: Why in Chess there is no obvious trend? In other words, what factors (other than formal) define how each opening changes its popularity over time?

I realize that popularity may be based not only on pure science, but on players' (aesthetic) preferences as well.

Why in Chess there is no obvious trend?

Because in chess there is no theory. The best you can get is the sorted list of moves that are currently considered strongest.

Furthermore, chess allows you to choose and to express your way of thinking/approaching the game. In chess you have a chance to create your own position while nature is already predetermined and we can only try to understand it and adapt to it. Rarely we get the chance to change/reimplement something.

Since we have a choice in chess, of course there will be different trends -> some will like quiet positional play, some will go for sharp bloodshed and some will be somewhere in between.

  In other words, what factors (other than formal) define how each opening changes its popularity over time?

Factors are listed in "the first thing that came to my mind" manner, not by their importance :

1. Number of lines player must learn;

Small number will be good for amateurs, since they can actually "have a life" and be able to learn all the intricacies of the opening.

For chess professionals the opening should have lots of branches and lines.

2. Can I obtain counterplay and how sound this opening is ?

Professionals dodge the forced opening lines because they might be refuted with computer analysis or with a strong analysis.

Amateurs love these since they can leave a computer to work 2 days and do all the "dirty work" for them ( and will do it better! ).

Opening must give the player equal chance to win the game, and player must have active counterplay. Days of waiting for opponent to make a mistake or "run out of steam" are gone.

3. How much explored it is?

New lines offer a lot of chances for winning, while explored ones usually end with a draw. This partly explains why some old openings got resurrected.

SUMMARY:

Opening trends are dictated by leading grandmasters and factors I described above.

With the emerging of strong chess software amateurs got the opportunity to compete with equal chances if he uses opening that is suitable for computer analysis and if he has decent playing strength.

Since popular openings are very well explored thanks to chess engines and enormous amount of games played, there was a danger of all grandmaster games ending in a draw. .

This was also foretold by Capablanca in the 1930s. In those days Black had a variety of good choices against 1.e4 so White turned to 1.d4 since all black had was Queen's gambit. This was an important thing since White had variety of lines to choose which can't be said for Black. Technically speaking, only White could win. Games became dull and technical for Black so after Second World War Black tried to find openings that gave him equal chances to win.

After Indian defenses were invented, Black entirely switched to ...Nf6 leaving 1...d5 as a relic of the past. Since the King's gambit was refuted and Italian game gave White nothing but a draw, people started playing Ruy Lopez.

Then came 1980s and computer revolution. After realizing that computer can calculate every forcing line with 100% precision people started to turn their attention to 1.e4 again, and to other forcing openings for Black hoping that the masters of the old missed something. In those days almost every opening was thoroughly played and many of them got revived. Especially is important Queen's gambit since many players like Kasparov and Karpov liked to have a solid opening that gave them a chance to outplay their opponent after defending successfully. The beauty of the Queen's gambit is that it embodies all the good sides of the 3 factors listed above: it remained sound/reliable for centuries, it is reasonably explored and can give Black equal chances. Indian defenses are prone to being "refuted" temporarily until someone with hard work resurrects them.

As for 1.e4, Ruy Lopez gave White permanent advantage ( although minimal one ) so Black tried to choose opening that gives equal chances but preserves solidity and soundness they had from 1...e5. There came Petroff's defense to the rescue. After a lot of analysis it has been proven it fulfills 2 factors listed above -> it was prone to refutation by a novelty at that time. Meanwhile, people also found that Marshall attack in Ruy Lopez can offer Black equal chances too so again people started playing 1...e5 more frequently. However, positional players disliked the sharped lines that could be refuted by a novelty and searched for solid openings. Then came Karpov and resurrected Caro-Kann. This opening suddenly got a burst in popularity since Karpov proved it satisfies all 3 factors listed above.

With the progress of chess software openings are analyzed very fast with little room for error. This results in professionals facing the "Capablanca prophecy" again, so they will again try to resurrect less known openings or invent new ones. One such example can be Scandinavian defense or Sokolsky attack, even Polish opening or Grob attack...

This is too broad to be explained here but I gave my best to explain it. If you need anything more leave a comment and I will reply.

Best regards.


Is it legal to play a move without hitting the clock? In the game Andrey Esipenko - Nihal Sarin (2018 World Blitz Championship), after 7. Qb3 c4 8. Qc2 Sarin plays 8... Bf5, and before he hits the clock, Esipenko plays 9. Qc1, but since Nihal has not pressed the clock Esipenko can't (this is the full video of the game).

As far as I understand this would lead to errors recording the game (because the DGT board only records a move when the clock is pressed). But how about the rules? Is this a breach? This is a blitz game and its obvious that both players let it go, but if either player appeals, who will get penalised?

Is this a breach?

No. Article 4.7 of the FIDE Laws of Chess defines when a move has been "made". Basically when your hand loses contact with the piece moved/captured/promoted etc. Once the move has been made the opponent may make a move. This applies whether clocks are being used or not.

If clocks are being used then the move is "completed" when the player presses the clock. If the player did not press the clock then it is completed when he makes his next move - article 6.2.1 -

  6.2.1 During the game each player, having made his move on the chessboard, shall stop his own clock and start his opponent’s clock
  (that is to say, he shall press his clock). This “completes” the move.
  A move is also completed if:
  6.2.1.1 the move ends the game (see Articles 5.1.1, 5.2.1, 5.2.2, 9.6.1 and 9.6.2), or
  6.2.1.2 the player has made his next move, when his previous move was not completed

When increments are used it is important that a player making a move should have the opportunity to press the clock and gain the increment. This is covered in article 6.2.2 -

  6.2.2 A player must be allowed to stop his clock after making his move, even after the opponent has made his next move.

Hence if the opponent makes his move before the player has pressed the clock then the player may press the clock without making a move and it is up to the opponent to press the clock back which most opponents would do immediately in a blitz game.

So, there is no breach, no penalty.


Top sources for opening theory Can anyone recommend any good sources such as periodicals, websites, or what not to stay up to date on the latest opening theory? I am willing to pay if the source requires such. How do the top Grandmasters stay up to date on the latest theory?

The top players in the world keep up with theory by actually looking at the latest games to be played. Every week, Mark Crowther collects all available games and prepares them in downloadable format here: http://www.theweekinchess.com/.

For players who can't look at a new move and instantly tell the ideas behind it (pretty much everyone below FIDE 2600), there is the Chess Informant: http://www.chessinformant.rs/. It comes out 4 times a year and has been in publication since 1966. It won't keep you nearly as current as checking the TWIC games every week but it will at least have someone to explain the moves to you.


How to play against the Noteboom variation? In online games I sometimes have this happen:

[fen ""]

1.d4 d5 2.c4 c6 3.Nf3 e6 4.Nc3 dxc4

and Black plays the famous "Noteboom variation".  I checked my database and I have in fact lost every single game as White where this variation happened. Usually Black just arranges his pieces nicely and pushes the a-pawn and b-pawn and I lose material due to pieces getting trapped in the corner, or having to give up pieces to stop the pawns promoting.

What is a promising way to meet this system for White?

Note: Of course, I could avoid the line with 4.e3 going into a normal Meran. But I often play quickly the first few moves of an internet game and carelessly make a natural developing move with the knight. It would be good to know how to recover from this.

In this variation, black is behind development after

[Event "?"]
[Site "?"]
[Date "????.??.??"]
[Round "?"]
[White "?"]
[Black "?"]
[Result "*"]
[WhiteELO "?"]
[BlackELO "?"]
[SetUp "1"]
[FEN "rnbqkbnr/pp3ppp/2p1p3/8/2pP4/2N2N2/PP2PPPP/R1BQKB1R w KQkq - 0 1"]

1. Bf4 Bb4 2. e3 Bxc3+ 3. bxc3 b5 4. a4 Nf6 5. axb5 cxb5 6. Rb1

White has more center control, and black will probably have a backward pawn if he tries to hang onto c4.

Another variation I like is

[Event "?"]
[Site "?"]
[Date "????.??.??"]
[Round "?"]
[White "?"]
[Black "?"]
[Result "*"]
[WhiteELO "?"]
[BlackELO "?"]
[SetUp "1"]
[FEN "rnbqkbnr/pp3ppp/2p1p3/8/2pP4/2N2N2/PP2PPPP/R1BQKB1R w KQkq - 0 1"]

1. e3 b5 2. b3 Bb4 3. Bb2 cxb3 4. Qxb3 Bxc3 5. Qxc3 Nf6 6. Bd3

which creates lots of attacking chances for white.


Huge difference between elometer.net approximation and other rating I have a chess.com 3-days-per-move rating of ~1400 and recently I played someone offline with a national ELO rating of ~1530 which was a surprisingly equal game (even according to the computer) until I eventually got a slightly worse position, blundered and subsequently resigned. I assume my national ELO rating (although I don't have one) would be between 1400 and 1500.

I found this website http://elometer.net, claiming to approximate your ELO strength (ostensibly with a 95% confidence interval of 250 points) by asking you which move you would play in 76 different positions (including, but certainly not limited to, tactical puzzles), and took the test.

Unfortunately for the authors of the test their estimation was about 500 (?!) points too high: I was estimated having a playing strength of ~1950 ELO with the "95% confidence interval" of [1829, 2079].

On the other hand, I remember taking this test one or two years ago, getting an estimation which was lower. IIRC (big if), the estimation then was around 1700. This correlates with my chess.com rating, which has improved by about 200 points since then.

The test appears to have some serious theoretical foundation and was made by people associated with a university in a major city in Germany, so I assume the people who made this are quite knowledgeable in their fields and knew what they were doing. Yet the test is quite inaccurate. Why did the authors publish this test? Do they actually believe the test is accurate? Why is it off by so much?

I recently took the test and the result was reasonable (around 2100), so it is not complete bogus.

However I am rather skeptical about such tests, since I believe that playing strength/Elo rating depends on more factors than finding the best move in a certain position; such as the following which are not really tested at elometer as far as I can see:

Can you concentrate for 4-6 hours that a game can last?
Do you blunder often?
Can you come up with good long time plans in the middlegame?
How good is your opening knowledge?
Can you spot the point in a game where you need to find a good/special move, i.e. the point where you have to invest some time thinking vs following a certain plan more or less automatically?

Regarding your comparison of online rating (1400), expected Elo of 1400-1500 and the elometer estimate of 1950, a few thoughts:

Any rating system is only relative to the pool of people playing. You cannot compare online ratings from one website with online ratings from another website or with the FIDE Elo.
You say your online rating is from 3 days/move game, which is a big difference to the Elo which is from normal games with hour long time scale.
In my experience players of your strength, particularly if they are beginning with chess, are not very stable in their playing strength. One game they might play like a grandmaster ;-) and in the next game, well...
There is a small (but finite) probability for you to score any Elo rating in the elometer test, so having just one outlier like yours does not mean that the test is bad.


What is the name of this pawn structure for black, with doubled c and f pawns? Is there any name for this pawn structure?

There is no special name for the structure you show where black has doubled c and f pawns.


What is the average age to become a grandmaster? On average, what is the age of people when they obtain the title of international master or grandmaster? I also wonder how the age distribution looks like.

Brilliant little data mining project!

I used the wiki list of GMs and wrote a quick and dirty script to extract the data. Feel free to use and expand/alter it, if you are interested.

As it turns out, the average age for reaching GM is just above 28. It is, however, skewed by "old" generation players and players from time before GM title was a thing. It was officially introduced in 1950 and some (old) players were awarded it at the time. It is intriguing to look at average age in different generations of players. And so:

For players born after 1945, the average is slightly above 26 years old.
For players born after 1970, the average is slightly above 23 years old.
For players born after 1975, the average is slightly above 22 years old.
For players born after 1980, the average is 21 years old.
For players born after 1985, the average is just shy of 20 years old.
For players born after 1990, the average is 18.5 years old.

Clearly, on average, people are becoming a GM faster nowadays! The age distribution (for players born after 1945) is as follows:

In case it is of interest, the two countries "producing" GMs on average at lowest age are India and China - both at 21 years old. Countries with most GMs (all time) are Russia (by huge margin), Ukraine, Germany, USA and Hungary.


How to start learning chess? I have always wanted to learn how to play chess, but I don't know how to start. I downloaded chess apps on my smartphone and PC but I didn't learn anything. I also contacted some local chess clubs to subscribe but they couldn't help me further.

My question is: What should I do to become a good chess player and learn the rules of the game very fast?

This will be a subjective answer (and a self-plug), but I believe that you'll find my website Chesscademy very helpful in learning the ropes. You can watch videos, tackle exercises, and complete quizzes. The educational material is structured such that even someone who has never even heard of chess before can easily get started.


Kramnik - Karjakin in the FIDE Candidates 2014, was 8...f5 correct? In the game between Kramnik and Karjakin shown below, the opening was a bit strange and the resulting position was odd. I am wondering, was 8...f5 correct? Was it a novelty of sorts or when did the game leave the established opening theory in this line? Thanks!

[Event "FIDE Candidates Tournament 2014"]
[Date "2014.03.14"]
[Round "2"]
[White "Kramnik, Vladimir"]
[Black "Karjakin, Sergey"]
[Result "1-0"]
[FEN ""]

1. d4 d5 2. c4 dxc4 3. e4 Nf6 4. e5 Nd5 5. Bxc4 Nb6 6. Bd3 Nc6 7. Be3 Nb4 8. Be4 f5 9. a3 fxe4 10. axb4 e6 11. Nc3 Bxb4 12. Qh5+ g6 13. Qg4 Bxc3+ 14. bxc3 Qd5 15. Ne2 Bd7 16. O-O Qc4 17. Ng3 Bc6 18. Ra5 O-O-O 19. Rc5 Qb3 20. c4 Kb8 21. Qxe6 Rde8 22. Qh3 Nxc4 23. Rxc6 bxc6 24. Nxe4 Nb6 25. Nc5 Qd5 26. Rc1 Ka8 27. Na6 Kb7 28. Nb4 Qf7 29. Qg4 Nd5 30. Nxc6 Re6 31. Na5+ Ka8 32. Qe4 Rb6 33. g4 h5 34. Rc5 Rd8 35. Nc6 Rxc6 36. Rxc6 hxg4 37. Rf6 Qh7 38. Bg5 Qg8 39. Rxg6 1-0

8...f5 is no novelty. It is a well known line and has been played successfully before by strong players like Adams, Salov and Karjakin himself.

8...f5 is absolutely the correct move in the position, because it practically forces White to either surrender his strong central pawn on e5 or give up his strong light squared bishop for Black's knight on b4. I demonstrate a line below showing what happens if White tries to avoid both these possibilities with 9. Bf3.

   [FEN "r1bqkb1r/ppp1p1pp/1n6/4Pp2/1n1PB3/4B3/PP3PPP/RN1QK1NR w KQkq f6 0 9"]

   1. Bf3 f4! 2. Bxf4 Qxd4 (2... Bf5!?) 3. Qxd4 Nc2+ 4. Kf1 Nxd4=

Thus, in the above position, White is practically forced to concede one of the two advantages.

Normally, White players preferred to play 9.exf6 for "obvious" reasons like the light squared bishop is stronger than the knight on b4 and is White's most valuable piece in launching a kingside attack.

Thus, in this position the move 9. a3!? must have come as a complete shock to Karjakin. It has never been played before at Grandmaster level and was only played once before in Janczarski,M (2335)-Bartel,M (2273) Warsaw 2013 (source here).

   [FEN "r1bqkb1r/ppp1p1pp/1n6/4Pp2/1n1PB3/4B3/PP3PPP/RN1QK1NR w KQkq f6 0 9"]

   9. a3!?

Whether 9.a3!? is good or bad is a different question. It seems to me that after

   [FEN "r1bqkb1r/ppp1p1pp/1n6/4Pp2/1n1PB3/4B3/PP3PPP/RN1QK1NR w KQkq f6 0 9"]

   9. a3 N4d5 10. Bf3 Nxe3 11. fxe3 g6 12. Ne2 Bh6!

Black is perfectly fine.

Conclusion: 8...f5 is correct!