Ethics of play in the last rounds of a tournament

USCF rule 14B6 states that "it is unethical and unsporting to agree to a draw before a serious contest has begun".

Also, according to USCF rule 20L, manipulating results is not only prohibited, "severe sanctions" are called for, which might even include revocation of the offenders' USCF memberships.

According to rule 20J, even discussing the possible results with your opponent is improper.

You are not, however, required to ignore the crosstable.  There's nothing wrong with taking a draw to ensure a tournament prize - provided you don't collude with your opponent.


This isn't an online solution but one program you could use is swiss perfect, which manages tournaments and allows various options.


Longest DTC in the endgame KQPKQ depending on the place of the white pawn

Here is a partial answer.

The paper Chess Endgames: Data and Strategy by Tamplin and Haworth reports, among other things, the maximum depth-to-conversion (DTC) and depth-to-zeroing (DTZ) among winning KQPKQ positions. Table 1b in the appendix indicates a maximum DTC of 114 among winning white-to-move positions, and Table 2a indicates a maximum DTZ of 71 for the same.

That article unfortunately does not include separate maximum DTC or DTZ metrics for the 4 respective queenside pawn options, but I can at least confirm that the maximum DTZ of 71 involves a rook pawn, and this maximal example was already given in Thompson's pioneering 1986 tablebase paper Retrograde Analysis of Certain Endgames. On p.138, the following position and maximal play line are indicated:

[Event "Thompson 1986"]
[Site "?"]
[Date "????.??.??"]
[Round "?"]
[White "KQPKQ"]
[Black "Maximum DTZ"]
[Result "1-0"]
[FEN "8/q7/P6k/Q7/8/8/8/6K1 w - - 0 1"]

1.Kg2 Qg7+ 2.Kh1 Qf6 3.Qd2+ Kg7 4.Qd7+ Kg6 5.Qd3+ Kg7 6.Qg3+ Kf8 7.Qb8+
Kf7 8.Qc7+ Kg6 9.Qc4 Qf3+ 10.Kh2 Qe3 11.Qf1 Qe5+ 12.Kh1 Qh8+ 13.Kg2 Qa8+
14.Kg1 Qa7+ 15.Kh1 Qd7 16.Qf2 Kh5 17.Qe2+ Kg6 18.Qe4+ Kh5 19.Qc4 Qa7 20.
Qe2+ Kg5 21.Kg2 Qd4 22.Qf2 Qe4+ 23.Qf3 Qd4 24.Qe2 Kg6 25.Qb5 Qe3 26.Kf1
Qe4 27.Kf2 Qd4+ 28.Kf3 Kh6 29.Qc6+ Kg7 30.Qc7+ Kg6 31.Qg3+ Kh5 32.Qh3+ Kg5
33.Qe6 Qd1+ 34.Qe2 Qd5+ 35.Kf2 Qf5+ 36.Kg1 Qb1+ 37.Kg2 Qg6 38.Qc4 Kh5+ 39.
Kf2 Qf6+ 40.Ke3 Qe5+ 41.Kd3 Kg5 42.Kc2 Qe3 43.Kb2 Kg6 44.Qb5 Kh6 45.Kc2
Qe6 46.Kc3 Qd6 47.Kc4 Kg7 48.Qg5+ Kh8 49.Qh5+ Kg7 50.Qg4+ Kf7 51.Qf5+ Kg7
52.Qc8 Qf4+ 53.Kb5 Qf6 54.Qc6 Qb2+ 55.Kc5 Qf2+ 56.Kd6 Kg6 57.Kd5+ Kh7 58.
Qc7+ Kh8 59.Qc3+ Kh7 60.Kc6 Qf5 61.Kb6 Qe6+ 62.Kb7 Qe4+ 63.Kb8 Qb1+ 64.Kc7
Qa2 65.Qc6 Kh8 66.Kb8 Qb3+ 67.Qb7 Qg3+ 68.Ka8 Qh3 69.Qc6 Qg4 70.Qc3+ Kh7
71.a7 1-0


Comparing 9...a6 to 9...b6 in the Panov-Botvinnik Attack

This will be a short answer as unfortunately I don't have much time (last minutes of my break :) ).

In a nutshell: Both options are quite playable but result in slightly different structures, so it's up to you to decide which one leads closer to something you're more familiar with. As to why both moves 9...b6 and 9...a6 are equalizing for black, it lies in the fact that white has not castled yet and therefore they cannot really emphasize on black's slow development and there are no immediate pawn breaks left for them in the centre. All of which means, that extra tempo white has to invest for castling allows black this added flexiblity in choice.

A slightly more concrete look at some lines: (please do check everything here with an engine, I don't have time/option to do that now)

White has no immediate ways of challenging b6: for example, with the king still in the centre, the immediate d5 (i), trying to liquidate the IQP and open up the centre bears no relevance as it easily leads to a much better endgame for black (with all the initiative):

(i)

 [title "immediate d5 after 9...b6"]
 [fen "rnbq1rk1/p3bppp/1p2pn2/3P2B1/2B5/2N2N2/PP3PPP/R2QK2R b KQ - 0 10"]

 1...Nxd5 2.Bxd5 exd5 3.Qxd5 Qxd5 4.Nxd5 Bxg5 5.Nxg5 Re8+ 6.Ne3 Ba6 {forcing white to castle long} 7.O-O-O Nc6 8.Kb1 Nb4 {thanks to weakened light squares black has great initiative, trade 1 pair of rooks and plans of Bd3-Bg6 following by Nd3 are always out there, where white's minor pieces can only be defensive.}

Now let's see what difference it would make if in the same position as (i) white's king was already safe/castled:

(ii)

 [title "Same position as (i) but assuming white's castled short already"]
 [fen "rnbq1rk1/pp2bppp/4pn2/6B1/2BP4/2N2N2/PP3PPP/R2Q1RK1 b - - 0 1"]

 1... b6 2. d5 Nxd5 3. Bxd5 exd5 4. Bxe7 Qxe7 5. Nxd5 Qd8 6. Rc1 Na6 7. Ne5 {A completely different end result, both sides have quite a healthy structure but if anyone it's white with an extra positional edge, in contrast to previous case where black was leading a better endgame.}

These lines underline the fact that white cannot really commit to much in the centre here (in order to pressure black by any means) without castling first, therefore black really does have an extra tempo at their disposal to choose either the immediate b6 or the somewhat slower but more sensible a6 (as it also provides important control over b5, which can still be followed by b6-Bb7 with the added advantage that you're in time to respond to a4-a5 with b5).

A tad more on the 9...a6 line followed by a simple developing plan leads to a very decent position with active ideas for both sides: white's play should revolve around emphasizing the IQP to establish a centralised knight on e5 (in other words making use of the extra dark square control provided by d4), and in contrast black's play is to exploit the IQP structure in order to establish a minor piece on d5 blockading the pawn and keeping the prospect of the d4 pawn potentially becoming a weakness, while activating the somewhat passive d7 bishop.

(iii)

 [title "One possible continuation after 9...a6 Nc6 Bd7"]
 [fen "rnbq1rk1/pp2bppp/4pn2/6B1/2BP4/2N2N2/PP3PPP/R2QK2R b KQ - 0 9"]

 1...a6 2. a4 Nc6 3. O-O Bd7 4. Qe2 Nb4 {preparing Bc6 to d5, one way or the other black is here in time to establish a piece on d5 blockading d4's advance} 5.Ne5 Bc6 6.Rad1 Bd5 7.Nxd5 (7.Bxf6 Bxf6 8.Nxd5 Nxd5) Nfxd5

Finally, not much else to say about b6 as it is equally decent: the light square fianchetto is quite fitting for black in all these kinds of IQP structures, as white often cannot easily challenge the bishop by either trading it or closing the diagonal, and on the other hand black ends up with a well active bishop which also provides additional control over d5.


Which one is more important between endgame studies and tactics?

Endgame studies are a particular form of tactical problem. I think variety is always good here, but, most importantly, since consistency is critical for improvement at chess, I would suggest you to focus on the type of exercise you enjoy most! (You won't train for too long if it's a sacrifice rather than a pleasure.)

I disagree with the "tactics can lead to speculation" part. Quite the opposite, training tactics is what we do to find concrete realizations of our intuitions/speculations. Of course, this means trying to calculate the entire continuation from the starting position, with all the possible consequences of the moves you are thinking about being considered. But this also applies to solving endgame studies, though!

Finally, I'd say that endgame studies seldom cover relevant strategy, and when they do, it's in a very artificial form. Anyway, if we wanted to improve our chess strategy, why not study chess strategy itself?

In conclusion, I think endgame studies can help you improve your tactical skills, but I'd use them as an additional resource rather than the main focus of your training. Tactical puzzles often have the advantage of being closer to positions you can reach in a real game (you are forced to "remove the noise" and find what's the relevant factor that can lead you to a win.) This does not mean that you should disregard the Master's advice, but rather stick to what's useful from it, so: beware of speculation during your tactical training!


Looking for an opening that had been wrongly evaluated for years

Maybe Martin Gardner was writing about this story. I'm quoting from p. 95 of Irving Chernev and Fred Reinfeld, The Fireside Book of Chess, Simon and Schuster, New York, 1949. (Of course they gave the moves in descriptive notation.)

  In the eighth edition of a popular manual by Dufresne and Mieses, the following line of play is given:

[FEN ""]

1.d4 d5 2.c4 e6 3.Nc3 c5 4.Nf3 cxd4 5.Nxd4 e5 6.Ndb5 d4 7.Nd5 Na6 8.Qa4 Bd7 9.e3 Ne7

  In this situation, the authors' comment is, "Black has the superior position." What the analysts seem to have overlooked is that White can mate on the move!

I'm guessing Kt-B3 was somehow typoed into Kt-K2.


What is the largest amount of players at once that can play during a single chess game?

I've played 3- and 4-board "bughouse" with 6 or 8 people total, and can imagine higher counts though the logistics must soon become unmanageable.

In another direction, you can have a consultation game on a single board.  Such games used to be 2-on-1 (handicap) or 2-on-2 affairs, but in the Internet age the number of players on a side is virtually unlimited, as was already seen in this famous game back in 1999.


Is there a live streaming of the WCC2018 of the players themselves?

I'm sure the official website (https://worldchess.com/) has it, which you'll need to pay.

Please note video of the players are copyright owned by World Chess. The games have no copyright but the video of the match is absolutely covered. YouTube users are not in a position to show you anything unless authorized.

It's like finding live World Cup soccer match on YouTube. It didn't happen, and won't happen to chess as well.


Which binary of Stockfish 7 should I use?

Open a terminal/console. Run the stockfish program, if the engine crashes move to the next one.

Type bench for the working binaries, and pick the one with best nodes/second.


A chess simultaneous display is where a strong player takes on more than one opponent simultaneously. Sometimes this is done with clocks but more usually without, when people must move when the simul giver arrives at their board.

Source: Chess Simul – Advice on giving and taking part, emphasis is mine

I would suggest using a single (normal) clock for all games. If a player (not the simul giver) has not ended their game after that time limit expires, then they lose on time. In this system, the simul giver cannot lose on time.

I would also advise that there is an arbiter present to prevent unreasonable delays when the simul giver comes to a player's board. In some simuls, a player is allowed three passes when the simul giver arrives at their board.


What are the most instructive Zurich 1953 games?

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

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

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

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

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


Is rotating a pawn so that it faces a different direction and then moves in that direction technically permitted according to the 2018 FIDE Laws?

This sort of thing is what the Preface of the Laws of Chess is for:

  PREFACE

  The Laws of Chess cannot cover all possible situations that may arise
  during a game, nor can they regulate all administrative questions.
  Where cases are not precisely regulated by an Article of the Laws, it
  should be possible to reach a correct decision by studying analogous
  situations which are discussed  in  the  Laws. The  Laws  assume
  that  arbiters  have  the  necessary  competence,  sound  judgement
  and absolute objectivity. Too detailed a rule might deprive the
  arbiter of his freedom of judgement and thus prevent him from finding
  the solution to a problem dictated by fairness, logic and special
  factors.

  FIDE appeals to all chess players and federations to accept this view.

No, the laws don't define what the square in front of a pawn is. But arbiters have freedom of judgement to deal with that kind of omission from the rules.

And there is no way an arbiter will let you move a pawn in an illegal way during a FIDE tournament based on this argument.

It will just be treated as an illegal move (some bonus time for the opponent, have to make a legal move with the pawn if possible, and if it happens a second time the game is lost).


The classic game that is typically used to explain 'excessive' protection is Aron Nimzowitsch vs A Giese (played in 1913)

http://www.chessgames.com/perl/chessgame?gid=1316457

pay attention to moves 10. Nf3! (first defense of e5) then 11. Re1! (second defense), and finally 13. Bf4! (third defense of e5)


The book The Most Flexible Sicilian by Delchev & Semkov covers both the Kan and Taimanov. Each part contains a section that presents the main ideas before going into detailed theory. A more interactive and better introduction to the Taimanov is given by Sicilian Taimanov by Emms. It is part of Everyman's Move by Move series which presents a Q&A style.

The Kan and Taimanov are not as theoretical as the other Sicilians but is still very flexible and discussing plans in different variations will be cumbersome. I have found that looking at annotated games of well known practitioners is useful in learning plans in the opening. Some practitioners of the Taimanov are Ulf Andersson, Anatoly Karpov and Mark Taimanov.


Why is there a minimum rating gain when you win?

Fide has a rule saying that if one player is rated more than 400
  points higher than his opponent, their difference should be set to 400
  when calculating rating gain/loss. That means no matter how weak the
  opposition is, a GM (or anyone) will receive minimum 0.8 rating points
  for winning. What is the reason behind this?

This is an historical anomaly. Currently, apart from your first ever rating, every game is rated individually. This means that you can never lose rating points by winning a game (LRPBWAG). It wasn't always so.

I don't remember exactly when the change happened, 2008 I think, but before this ratings were calculated per tournament. What happened was that your rating was calculated using your score for the tournament, the average of your opponents' ratings and your expected score against them. This opened up the possibility of winning the tournament but losing rating points because some low rated players in the tournament, who you crushed, lowered the average rating for the tournament so much that even though you scored well against similarly rated players as yourself your rating went down.

The original solution to this was to limit the difference to 350 points. Later this was changed to 400. Now that games are rated individually it could be scrapped.

There was an article on Chessbase 6 years ago discussing this point between Jeff Sonas, Ken Thompson and John Nunn.

Part of John Nunn's contribution is worth quoting -

  The original rating rules had no 350-point rule. It must be remembered
  that in 1970 the rating list was very small and it was never envisaged
  that it would be extended substantially. Only top tournaments were
  rated (and these were invariably all-play-all events) and all
  calculations were done by hand. The 'Losing Rating Points For Winning
  A Game' problem didn't really arise. The top players always skipped
  the first round or two of an Olympiad, and in any case any weak
  opponents would be unrated, so the games simply didn't count.

  But times changed, the rating list expanded and started including more
  and more weaker players. Open tournaments appeared, and the LRPFWAG
  problem started to become significant. I don't remember exactly when
  the 350-point rule was introduced to deal with this, but I believe it
  was around 1980. Later, in 1988 or 1989, Karpov was unhappy about
  losing points when he had won a tournament, arguing that the aim of
  taking part in a tournament was to win it, and if you have achieved
  that then you shouldn't lose points through not having won by a large
  margin. For a time the 'Karpov rule' was in effect, that you couldn't
  lose points for winning an event. This was later scrapped.

  Rating games individually is a fairly recent innovation, and for the
  vast bulk of the lifetime of the Elo system it was done on a
  tournament basis (because it made the calculations easier, especially
  for all-play-all events). The current rule is in a way a hangover from
  the earlier times, but I think there is some logic in it, although one
  can argue over the exact details. Rapidly improving young players, for
  example, can be massively underrated.


How to play against the Noteboom variation?

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.


Chess problem - don't understand the solution

1...R8xe3 wins a piece (the knight on e3), because either recapture leads to worse things for White, since the d2 bishop is pinned to the white queen, and the f-pawn recapture opens the possibility of mate on g2:

[fen "4rbk1/pp3pp1/1nq4p/8/1PP5/P3N1P1/Q2BrP1P/3R1RK1 b - - 0 1"]

1...R8xe3 2.Bxe3 (2.fxe3 Qg2#) Rxa2


Are online USCF tournaments worth playing?

First of all, the vast majority of people are not cheating.  If they were, 1200 would be a master rating, and it's not.

Second, in a USCF rated game, you're not anonymous.  The games are connected to your real name and your USCF membership.  There might be some people willing to cheat anonymously who would be less willing if it could be traced back to them personally, and possibly put their offline membership at risk, rather than simply forcing them to make a new online account.

Third... yes, some people cheat.  If you do play against Stockfish (with or without added mistakes) once or twice, so what?  It won't be most of the time.

Fourth, if you're worried about cheaters affecting your rating, it appears that online play currently only affects your USCF "Blitz" rating, not your "Regular" USCF rating.

In summary:  If you think it would otherwise be a good idea, there's no reason to let the prospect of cheaters dissuade you.  (Although skipping club to play online would just be silly in most cases.)


Formal rules for two-player bughouse without a clock

In bughouse there are no formal rules, since bughouse isn't exactly a formal game :)

But from my experience, the two most common ways to deal with this are:

A player counts to 10 after moving, and his opponent has to move before he reaches 10.
You are only obligated to move once the person sitting diagonally from you (your opponent's partner) moves.

Other than these, I don't know of any other effective rules that would work.  I've played with some very strong bughouse players (borderline professionals), and even they often just resort to counting :)


He (author) explains how to go about getting this here. The sourceforge game databases are available here

Update:
 To go about downloading the database from the second sourceforge link provided above, the author provides instructions here (can do it directly form ChessDB's Tools menu).


There are a few classic reasons which tend to make exchanging pieces favourable. None of these are absolute; in any given position, short-term tactical considerations may dominate. But you might like to keep the following themes in mind which can favour exchanges:
(1) You have a material advantage.
(2) Your opponent has a space advantage (your position is cramped).
(3) Your opponent has dangerous prospects of an attack on your king.
(4) The structure of a position (most typically, the pawn structure) favours you in the endgame.
In addition there are many familiar patterns whereby an exchange creates an advantage for you. For example, the opponent has to accept doubled pawns by a pawn recapture; or the opponent has to give up the right to castle by recapturing with the king (this often applies to queen exchanges in the opening). Or a particular exchange favours you, because your piece is passive / badly placed, while theirs is active / well placed.
(And just to complete the answer: as several people pointed out already, exchanging doesn't typically "waste a turn" because the opponent also uses a move to recapture. If for some reason forcing an exchange does involve giving away the initiative, then indeed that will often be a factor against it.)


White openings for counter-attacking players

One might call the Reti a counter attacking opening for white.
White allows black to grab some space with a big centre and then tries to tear it down.

[FEN ""]

1. Nf3 d5 2. c4 d4 3. g3 Nc6 4. Bg2 e5

There also should be quite a lot of theoretical information about it. The main problem might be that black isn't easily goaded into overextending. Most players like to play it safe with black, making a counter attacking game with white less likely.


Giordano Vicoli's Chess_Studio (not to be confused with a similarly named e-reader app from Gambit Publications) seems to have many of the features you are looking for.  I've only tried Chess Studio Light, but it is able to import a much wider range of PGN files than any of the PGN viewer apps.  Within a PGN archive, you can view lists of games sorted by Event, Opening, Player or Year. The game window in the Lite version allows you to add nested variations and text and some NAGs (!, ?, only move, and novelty), but you may need the paid version to analyze with Stockfish as kibitzer, or add long lines of moves to a game.  You can save games, or send them by email.  It registers itself as a PGN program, so you can use the "Open in..." menu item to add PGN files to it from programs which have "Open in..."  You can download and upload from Dropbox and iCloud.  You can download from TWIC or PGN Mentor.  It also has Nalimov tablebases for 6 men endings.  In the paid version, it looks like you can play against Stockfish, and set its rating from 500-2500 elo with a choice of aggressive, active or solid styles.  You can set up a position, and play the engine from there.  There isn't a tree view or keys.  The openings index is sorted by ECO codes with no diagrams or names.  Even so, it's the most complete PGN editor/database I've seen for iOS.

In Smallfish, Smallchess and Stockfish, when you try to add a new variation, the app deletes the moves that were there before, so nesting is impossible.  They don't seem to allow you to add text comments or NAGs either.  Smallfish can display text comments from PGN files you import, but the moves in these comments are not clickable.

Re. Android, Chess PGN Master Pro, Droidfish and Chessbase Online all seem to allow you to annotate games, and add subvariations and some NAGs.  The Chessbase app for iOS seems to be more about just accessing their website.

Re. opening repertoires, I haven't tried the iOS version of Arnel Domingo's Chess Opening Trainer, just the Windows demo, but it lets you input your own repertoire, test it, and has trees.

I should also probably mention that there are a number of PGN Editors that you might be able to access online using Safari: Chess.com's Analysis Board Editor, Lichess.org's Board Editor, Apronus and Caissa's Web.  A lot of sites also have opening trees, eg. 365chess.com, Chessbase and ChessOK.


Soltis's best chess game of the 20th century

The move you gave looks fine. In my correspondence database I have 9 games in the position after 11...Bd6. Eight went for 12.Bxb5+, but one game (featuring a 2397 player from 2010) chose 12.Qe2. Even though the game is old, it gives some backing to 12.Qe2 because of the player's strength. Meanwhile, the strongest evidence in correspondence for 12.Bxb5+ comes from it being chosen in two more recent 2015 games by a 2166 and 2000 rated player. Both moves seem to indicate an advantage for White, given the results in correspondence (even though the latest games were from 2015, engine use was permitted).

At over depth 40, Stockfish 11 gives me around +3.48 for 12.Qe2. Meanwhile, 12.Bxb5+ hovers close to +2. After 12.Qe2 0-0 (12...Be6 13.Qf2 exf3 14.Bxb5+ Kd8 15.gxf3 is winning; meanwhile, 12...Bxg3+ 13.hxg3 Qxh1 14.Qxb5+ Bd7 15.Qxd5 is also extremely good) 13.fxg4 Bxg3+ (or 13...Nf6 14.g5 Ng4 15.Kd1 Bxg3 16.Kc2) 14.Kd1, we've followed your line. Stockfish gives over +3 for White, and that 2010 correspondence game I mentioned also reached this position. White went on to win the game without much trouble.

TLDR: the line looks to be safely refuted for Black after 12.Qe2.


How do GMs “play the man, not the board”?

As you mentioned, playing the man can mean several different things, but before I answer I want to say that no one can become a better player by only playing the man - objectivity is the number 1 priority.

Many top-level GMs do play the man and the most notable example I can give is the Kasparov-Kramnik match in 2000. Kramnik knew that Kasparov disliked queenless middlegames, so he put the Berlin into his opening arsenal. Kramnik also played d4 in his match because Kasparov was known to be a deadly Najdorf player (it should be noted that Kramnik did play e4 at that time). Another example that I can think of is a younger player taking advantage of an older player's fatigue and grinding the position down for hours. These are the main ways that GMs play the man as far as I know.


The best engine to use for analysis is most likely stockfish. Works with multiple procs, probably the strongest tactically. And as a bonus, it's free (but you should get a good UCI. I use Fritz UCI which is ok. An UCI that shows multiple lines of analysis at the same time is kinda mandatory). Imo using  an engine in correspondance chess is only interesting if you're strong enough to understand easily why the program makes the choices he makes. ie 2000+ fide at least. You will also notice some of their evaluation function flaws : for instance overvaluing lines which win a pawn but give opposite color bishops, for stockfish. Also sometimes giving more value to prophylactic moves than line opening moves, when in fact it's better to go for the lines opening immediately (it doesn't always realize how strong it can be because of horizons effects).


Potential Rating Gain if Only 20 OTB Games Per Year

I went to the FIDE rating calculator and inputted:

Your ELO of 1762
An estimate of your opponent's ELO of 1750 (assuming you play roughly equal opposition)
The development coefficient of 20 (representing that you have an established rating)

Per game you get a rounded rating change of:

+10 for a win
0 for a draw
-10 for a loss

At +4 in 20 games, your rating will change by +40 (4 wins to 16 draws) to -120 (4 wins, 16 losses).


White's reply against Reti advance (2...d4)

Focusing on the 3. g3 line, you have the Advance Variation of the Réti. There is an extensive discussion of this line available here, an offshoot of this page on Understanding the Réti.
These are the main lines listed there:

Main line:
a. 3...Nc6 4. Bg2 e5 5. d3 Nf6 6. O-O
b. 3...Nc6 4. Bg2 e5 5.O-O
c. 3...c5 4. Bg2 Nc6 5. d3
d. 3...g6 4. Bg2 Bg7
Critical line:
e. 3...Nc6 4. Bg2 g6 5. d3 Bg7 6. O-O

The reason for the popularity of 3. g3 is that by advancing to d5, black has weakened their hold on the center, opening the way for control of the center diagonal with a fianchettoed bishop. As noted by Bad_Bishop this is a reverse Benoni, with the crucial difference being that you have an extra tempo to play with. Alexander Delchev has a good book on the Réti, with 28 pages devoted to the reverse Benoni (The Modern Réti). As Delchev notes, you're likely going to want to make the most of your extra tempo and play a very sharp game. Unfortunately, this counts against 3. g3 assuming Black counters with 3. ...Nc6!. If, however, black plays 3. ...c5 then you can counter with a strategy similar to the Benko (likewise for 3. ...g6). I'll start with an overview of the kingside fianchetto, and then delve into specifics.
General Strategy for a Kingside Fianchetto
The purpose of 3. g3 ... 4. Bg2 is to exert control on the central h1-a8 diagonal with the fianchettoed bishop. This bishop will become the lynchpin of your King's defense, since any move of a pawn in front of the king opens lines of attack, as well as a great tool for indirect control of the center in the hypermodern style. This bishop is very valuable and should not be traded without significant advantage as compensation. The e2 pawn is usually important to keep in place to help protect f3 and avoid pesky attacks from a knight (but this rule of thumb has many exceptions). A common strategy for trading off bishops is for black to double their queen behind their bishop on the c8-h3 diagonal and then push Bh3, attempting to pin the fianchettoed bishop to the rook on f1 (after castling) and trade with Bxg2. In the event of a queenside castle by black, you could wind up with a pawn attack on the h-file, aiming to break up the pawn structure of your fianchetto (this is the common line in the Yugoslav attack in the Sicilian Dragon). Since you're playing white here and already have a slight developmental lead, however, this strikes me as too slow to be practical.
You typically want to avoid a closed position to exploit the full power of your bishop's influence on the central diagonal. Usually you will attack queenside, with a pawn storm in slow games and careful maneuvering of minor pieces in quicker games. Given this, your pawn chain will generally extend from e2 to c4, giving you a structure similar to what you would find in the English, Reverse Dragon variation. Your big obstacle here will be how to open a file for your queenside rook, given that trading cxd5 is no longer an option. For this reason b4, leading to something like the Benko gambit, will be a popular choice in most of the lines following 3. g3.
Black Plays 3. ...c5
[FEN " "]
1. Nf3 d5 2. c4 d4 3. g3 c5

With 3. ...c5 (as well as 3. ...g6) you win up in the reversed modern Benoni. This move serves two main purposes: it protects the pawn on d4 and allows development of the knight with Kc6 without blocking in the pawn on c7. You'll notice that black doesn't have a lot of control over the light squares -- this is something that will work to your advantage.
You want to stick to your plan of development play Bg2 and d3, getting the pawn structure I mentioned above. The main line above makes these moves immediately, with 4. Bg2 and 5. d3. Going this route will generally lead to a slower game where you launch a pawn storm on the queenside.
The more aggressive option is the reverse Benko Gambit given by 4. b4, preparing the way to open a file for your queenside rook. This is usually accepted with 4...cxb4. With 5. a3 you force Black's hand, and will usually be met with 5. ...bxa3 6. Bxa3.
[FEN " "]
1. Nf3 d5 2. c4 d4 3. g3 c5 4. b4 cxb4 5. a3 bxa3 6. Bxa3

At this point you should see that you've gotten a considerable amount for that pawn. You have your rook on an open file, with another open file right next door on b, and you have developed your queenside bishop to possibly assist in a queenside attack (but likely not).
Black's strategy at this point is usually going to involve 6. ...Nc6 followed by e5, at which point you'll be forced to trade bishops on f8. Your plan is going to involve finally completing the fianchetto with Bg2 and following up with d3 for the e2-c4 pawn chain -- extending towards your point of attack. See the linked page for more discussion.
Black Plays 3. ...g6
[FEN " "]
1. Nf3 d5 2. c4 d4 3. g3 g6

Like 3. ...c5 this usually winds up in a variant of the reversed Modern Benoni, but a bit slower for Black. Given how sharp that defense is, the extra tempo can be exploited to great advantage. You're going to likely want to pursue a similar strategy involving a Benko-like push to b4, assuming that black eventually plays c5. Otherwise, it will likely transpose into the critical line (e) -- though Delchev disagrees that (e) is the line to worry about.
Black Plays 3. ...Nc6
[FEN " "]
1. Nf3 d5 2. c4 d4 3. g3 Nc6

This is usually considered Black's best line. Your plan will stay largely the same. You'll follow with Bg2 and d3, leading to a queenside attack. I typically prefer to hold off on castling, so would probably opt for the sequence in the main line (a). The point of 4. ...e5 is obviously the same as the move of the pawn to c5 in the other variation -- to protect the pawn on d4. You might be tempted to attack with f4, but I'd (generally) avoid weakening your fianchetto with such a move. The central diagonal is still open for your fianchettoed bishop, but you'll have to pay attention to the c pawn since c6 is still on the table once the knight is moved -- weakening your bishop's control of the diagonal. Better to simply follow with 5. d3 or 5. O-O (with the move you don't make coming shortly after).
Suppose the sequence goes as follows: 4. Bg2 e5 5. O-O Nf6 6. d3. The move Delchev considers best for black here is 6. ...a5!, which pre-empts the Benko-like push 7. b4.
[FEN " "]
1. Nf3 d5 2. c4 d4 3. g3 Nc6 4. Bg2 e5 5. O-O Nf6 6. d3 a5!

This sequence is actually what leads Delchev to reject 3. g3 as being too slow (he comes to a similar conclusion regarding 3. e3 which is also best responded to with 3. ...Nc6 and popularly continued with 4. exd4 Nxd4 5. Nxd4 Qxd4 6. d3 c6! which tends to cramp White's position and restrict its knight).
This line is one case where the e3 pawn seems advisable. See this game between Kujawski and Kiolbasa to get an idea of how things might develop. The basic idea will be to follow with 7. e3, which is best answered by 7. ...dxe3! since allowing White to initiate the trade with something like 7. ...Be7 8. exd4 exd4 9. Na3 O-O 10. Nb5 aids your development by giving you the active knight.
[FEN " "]
1. Nf3 d5 2. c4 d4 3. g3 Nc6 4. Bg2 e5 5. O-O Nf6 6. d3 a5! 7. e3 dxe3 8. exd4 exd4 9. Na3 O-O 10. Nb5

Now, the Critical Line according to the linked page is 3. ...Nc6 4. Bg2 g6 5. d3 Bg7 6. O-O.
[FEN " "]
1. Nf3 d5 2. c4 d4 3. g3 Nc6 4. Bg2 g6 5. d3 Bg7 6. O-O

Delchev actually doesn't consider this, having concluded that the previous sequence involving 6. ...a5! as decisive against 3. g3. From my analysis, I think Black's best strategy here is to simply follow normal development. The pawn on d4 is awkwardly placed since it blocks the fianchettoed bishop. So, I'd figure this would continue with 6. ...Nf6 7. b4, preparing to pseudo-sac the b-pawn in order to open a file for the rook and establish an attack.
[FEN " "]
1. Nf3 d5 2. c4 d4 3. g3 Nc6 4. Bg2 g6 5. d3 Bg7 6. O-O Nf6 7. b4

If 7. ...Nxb4 then 8. Qa4+ Nc6 9. Ne5 putting a lot of pressure on c6.
[FEN " "]
1. Nf3 d5 2. c4 d4 3. g3 Nc6 4. Bg2 g6 5. d3 Bg7 6. O-O Nf6 7. b4 Nxb4 8. Qa4+ Nc6 9. Ne5

Black can go with either 9. ...O-O or 9. ...Bd7. Either way you capture 10. Nxc6 and eventually get Black's b-pawn or a nice lead in development and good initiative. For 9. ...O-O we have
[FEN " "]
1. Nf3 d5 2. c4 d4 3. g3 Nc6 4. Bg2 g6 5. d3 Bg7 6. O-O Nf6 7. b4 Nxb4 8. Qa4+ Nc6 9. Ne5 O-O 10. Nxc6 bxc6 11. Qxc6

Whereas for 9. ...Bd7 there are two branches,
[FEN " "]
1. Nf3 d5 2. c4 d4 3. g3 Nc6 4. Bg2 g6 5. d3 Bg7 6. O-O Nf6 7. b4 Nxb4 8. Qa4+ Nc6 9. Ne5 Bd7 10. Nxc6 Bxc6 11. Bxc6 bxc6 12. Qxc6

and
[FEN " "]
1. Nf3 d5 2. c4 d4 3. g3 Nc6 4. Bg2 g6 5. d3 Bg7 6. O-O Nf6 7. b4 Nxb4 8. Qa4+ Nc6 9. Ne5 Bd7 10. Nxc6 bxc6

If you face the latter, I'd hold off on taking the pawn and develop your knight and rook with Nd2, Nb3, and Rb1.
Why does Delchev suggest 3. b4?
Though my main focus has been exploring 3. g3 and trying to provide some insights into the dynamics of play with a kingside fianchetto, Delchev recommends 3. b4 as the best move.
[FEN " "]
1. Nf3 d5 2. c4 d4 3. b4!?

His reasoning is that it offers you the sharpest play and makes the most of the extra tempo. You essentially jump right into a Benko-like gambit and exert maximum pressure. Optimal play continues 3. ...f6! (as you note) then 4. e3 e5! where it gets tricky. You have to be bold. VERY bold (not for the faint of heart). 5. c5 positions White for another gambit and is best answered by 5. ...a5!.
[FEN " "]
1. Nf3 d5 2. c4 d4 3. b4!? f6! 4. e3 e5! 5. c5 a5!

From this point, the main lines break into 6. Nxe5, 6. Bc4, 6. Bb5+.
The move 6. Nxe5 leads to a forced draw after 6. ...fxe5 7. Qh5+ Kd7 8. Qf5+ Ke8 9. Qh5+:
[FEN " "]
1. Nf3 d5 2. c4 d4 3. b4!? f6! 4. e3 e5! 5. c5 a5! 6. Nxe5 fxe5 7. Qh5+ Kd7 8. Qf5+ Ke8 9. Qh5+

With 6. Bc4 you face 6. ...axb4! then play naturally continues 7. exd4 exd4 8. O-O Bxc5 and now Black has two pawns and more space.
[FEN " "]
1. Nf3 d5 2. c4 d4 3. b4!? f6! 4. e3 e5! 5. c5 a5! 6. Bc4 axb4! 7. exd4 exd4 8. O-O Bxc5

It seems the line following 6. Bb5+ is the key. It leads to very sharp play, and while not necessarily to White's advantage, the knowledge imbalance should tip the scales in White's favor. The theory ends with 6. ...c6! 7. Bc4 Ne7!? 8. O-O!? axb4 9. Bb2, at which point Delchev concludes that White has compensation for the pawn and the attack.
[FEN " "]
1. Nf3 d5 2. c4 d4 3. b4!? f6! 4. e3 e5! 5. c5 a5! 6. Bb5+ c6! 7. Bc4 Ne7!? 8. O-O!? axb4 9. Bb2

The critical line continues 9. ...dxe3 10. fxe3 Nf5 11. Qe2 Bxc5 12. d4 Ba7!:
[FEN " "]
1. Nf3 d5 2. c4 d4 3. b4!? f6! 4. e3 e5! 5. c5 a5! 6. Bb5+ c6! 7. Bc4 Ne7!? 8. O-O!? axb4 9. Bb2 dxe3 10. fxe3 Nf5 11. Qe2 Bxc5 12. d4 Ba7!

At this point the three branches considered by Delchev are 13. a3?! e4, 13. dxe5 Nd7!, and 13. Nbd2 Qe7 -- none of which are simple or clear cut. Engines can hold the line for Black, but things are complicated to say the least. From what I can tell, the idea is a continuation of the theme of this variation: make things sharp, make things complicated, and hope you know more about the opportunities and pitfalls of the variation than your opponent. For what it's worth, I play the Sicilian Dragon with the same strategy in mind. If my opponent knows the Yugoslav attack -- and they usually do if they're any good -- I believe they have a slight edge on paper. But the opening is so sharp and bookish (I believe the book line is settled for something like 22 moves) that unless I'm against another Dragon specialist they can rarely avoid some mistake that I know how to exploit.
The Bottom Line
The line with 3. e3 is safe and slow, perhaps too slow (though I haven't discussed it in detail). At any rate, it isn't my style. 3. g3 has potential if you're able to exploit some of the gambit opportunities, but could be turned into a slower game in the 3. ...Nc6 line. 3. b4 is very aggressive and sharp, but an interesting option if that's your thing. I'd probably go with 3. g3 since I'm more familiar with that sort of pawn structure and I'm a big fan of keeping the pawn structure similar across my various openings/defenses. If, however, you're not comfortable playing with fianchettoed kingside bishops and aggressive gambits then it might be a bit much for you to jump right into.


What are the normal non-symmetric black responses to 1. d4

There are a number of Black openings you can play in response to White playing 1. d4 (I'm assuming this is what you mean by "Queenside opening").

Here is a good list of Black openings against d4 you can look up that avoid symmetrical positions and promise good tactical play:

King's Indian Defence (1. d4 Nf6 2. c4 g6 3. Nc3 Bg7 4. e4 d6)
Benoni Defense (my opening: 1. d4 Nf6 2. c4 c5 3. d5 e6 4. Nc3 exd5 5. cxd5 d6)
Albin Counter-Gambit (1. d4 d5 2. c4 e5!? 3. dxe5 d4)
Dutch Defence - Leningrad variation (1. d4 f5 2. c4 Nf6 3. g3 g6 4. Bg2 Bg7 5. Nf3 0-0)

There are many more, but I would recommend looking at one of these, based on what you've told me.  If you're looking for something where you're on the offensive immediately and there isn't too much theory to memorize, I would go with the Albin Counter-Gambit.

To look up an opening, I would recommend going to chess.com and finding a forum or article where the opening is discussed.  Then, I would recommend looking up some games online of strong Grandmasters playing the opening (just type into Google:  Albin Counter-Gambit Grandmaster games).

If you like the opening, the next step would be to buy a book on it - the Everyman books are relatively simple.


An aggressive opening for Black against 1. e4

White is one move ahead, and attacking. You can't be aggressive yet, or you'll just lose!

You have two choices: either you try to contain white, and when that is done and the position is equal, then you try to become active yourself. Or, you let him expand, but make sure you'll have your own trumps as well. The first way will lead to more or less symmetric positions, the second way is only possible if you make the position as asymmetric as possible: then he can have his trumps, and you can have yours.

The most famous asymmetric way of playing against 1.e4 is the Sicilian.

[FEN "rnbqkbnr/pp2pppp/3p4/8/3NP3/8/PPP2PPP/RNBQKB1R b KQkq - 0 4"]

Example Sicilian after 1.e4 c5 2.Nf3 d6 3.d4 cxd4 4.Nxd4.

If white goes for this (he has plenty other options that are very strong too, black has other 2nd moves with the same idea), then he played 3.d4 to open the center, he'll have extra space, open diagonals for his bishops and great chances of an attack -- but you'll have your trumps too. You have 2 pawns vs 1 in the center, can move a rook to the c-file, and you have no weaknesses. You're very far away from having your own attack, but if white expands too much... BOOM. Not easy to play, but white has no way to simply control the game from here, he needs to attack.

Another way is the Pirc / Modern, characterized by putting a bishop on g7. With Nf6 in it's a Pirc, without it's a Modern. E.g.,

[FEN "rnbqk2r/ppp1ppbp/3p1np1/8/3PPP2/2N2N2/PPP3PP/R1BQKB1R b KQkq - 2 5"]

Again a very asymmetric position, white and black are doing very different things. But white has much more space, and he's looking for an attack. Black is thinking that he will be able to defend, and then, white will have thrown too many pawns ahead, leaving behind all kind of empty space... again, counter attack coming up, if black survives.

So those are ways to play for the counter attack; counter attack is only possible if you manage to weather the attack first.

Otherwise, forget about attacking for now, and try to get an equal position.


What are some examples of wins by a much weaker player?

In 2009, GM Nurlan Ibrayev of Kazakhstan (rated 2407 at the time) lost a classical time control game to 9-year-old Hetul Shah of India, who then had a FIDE rating of 1817. Shah's current rating, now three years after that game, is 1979, not so much higher than it was at the time of his upset victory. So this game wasn't a case of Ibrayev running up against some seriously underrated prodigy whose rating was about to shoot up several hundred points. To the contrary, this seems to be exactly the sort of game you are after: a much weaker player having a good day and taking a grandmaster scalp, with the black pieces no less!

[FEN ""]
[Event "7th Parsvnath International Open"]
[Site "Delhi"]
[Date "2009.01.11"]
[EventDate "2009.01.11"]
[Round "1.36"]
[Result "0-1"]
[White "Nurlan Ibrayev"]
[Black "Hetul Shah"]
[WhiteElo "2407"]
[BlackElo "1817"]
[PlyCount "88"]

1.e4 e5 2.Nf3 Nc6 3.Bb5 a6 4.Ba4 Nf6 5.O-O Be7 6.Re1 b5 7.Bb3 d6 8.c3 O-O
9.h3 Na5 10.Bc2 c5 11.d4 Qc7 12.Nbd2 cxd4 13.cxd4 Bd7 14.Nf1 Rfc8 15.Ne3 Nc6
16.a3 Bf8 17.b3 Nxd4 18.Nxd4 Qc3 19.Ne2 Qxa1 20.Qd2 d5 21.b4 d4 22.Nd1 Rxc2
23.Qxc2 Rc8 24.Qd2 Nxe4 25.Qd3 Nd6 26.Bb2 Qa2 27.f4 Qc4 28.Qb1 d3 29.Ne3 Qe4
30.Nc3 Qxf4 31.Ncd5 Qg3 32.Nf1 Qg6 33.Bxe5 Nc4 34.Nf4 Qb6+ 35.Kh1 Nxe5 36.Rxe5
Bd6 37.Re4 Bc6 38.Qc1 Qb7 39.Re1 Bxg2+ 40.Nxg2 Rxc1 41.Rxc1 Bf4 42.Rc3 d2
43.Rd3 h6 44.Kg1 Qb6+ 0-1


This does not make any difference.  Exchanging the positions of king and queen on both sides just corresponds to mirroring the whole game horizontally.  Thus they are equivalent.


Is PGN split utility available anywhere?

As of 2017.04.01, pgn-extract (version 17-38) does provide variation splitting functionality via its --splitvariants flag. So, if you want this in a Windows/Linux/Mac OS environment it is available. Disclosure: I am the author of pgn-extract.


Because the rook on b7 is en prise. It is attacked twice (by the rook on h7 and the bishop on g2) and only defended once (by the bishop on c8). Either way the game is lost.


Are USCF regular ratings more accurate than quick or blitz ratings in regards to quick or blitz games?

Probably not technically if everyone played a lot of rapid games, however, I have seen organizers do this before since the regular ratings usually have a more established basis. In other words, because people have usually played a lot more standard rated games, in that respect, they are more accurate. It helps prevent sandbagging.

In reality, in rapid and blitz, a better predictor is probably age. Kids often perform better than their standard rating the faster the game. I once won an under-1800 blitz tournament when I was an under-rated 1100-player (I went up to 1254 after the main tournament). I was about 18, and the mind was very quick back then (there also were not a lot of kids like there are today).


What is the theoretical assessment of this 4 knights gambit?

At depth 19, Komodo gives an equal evaluation (+0) after 8.Ng1 (and according to Komodo all moves were best leading up to that point after 4...Nxe4). However, it says that 8.Nh4 gives White a +0.32 advantage.

It's hard to judge the theoretical assessment just by an engine's evaluation from the 8th move, but there are only a few games played in my database so there's not much to go on. Overall it seems absolutely playable for Black and funner to play from his side of the board. But objectively White probably has some slight advantage.


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

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

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

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

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

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

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

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

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

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

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

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

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

The "Immortal Draw" game:

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

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

You can find many more in these game collections:

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


Where do I play online games with a long time control?

On chess.com, there are at least two groups of people interested in games with long time controls (e.g. 90'+30'' and 45'+45''): the Slow Chess League and the Slow LIVE Chess Association.

They have regular Swiss style tournaments where you have to agree on a date with your opponent under pretty elaborate rules (including penalties for not showing up).

This is not exactly what you asked (random, instantaneous pairing), but probably the better way. The problem with long time controls online is not only finding people who want to play, but discouraging people from losing interest and quitting.

As far as I know, these were founded on ICC when chess.com didn't exist yet. So maybe there is something similar on ICC.


Chess Logic - Tigran Petrosian's doctoral dissertation

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.)


Morozevich variant in the Tarrasch french

I don't think Black is in a hurry to develop the knight.  4...c5 is the main move.  If White plays Qg4 the bishop goes back to f8.  As a matter of fact the bishop sometimes goes back to f8 even if White doesn't play Qg4.

Of course Nh6 is fine and the knight will then go to f5 where it is happy.

Note:  1. There are other lines where the Bishop returns to f8, like 1.e4 e6 2.d4 d5 3.Nc3 Bb4 4.e5 b6 5.Qg4 Bf8.
2. In non-Nf6 lines it is common for the knight to head to f5 via e7 or h6


After clicking on the king, the rook is outlined in green, as shown in your both your own image, and mine below.

If you click the rook after clicking the king, castling will occur, shown in the image below:


The best way is read source code yourself. https://github.com/official-stockfish/Stockfish/blob/master/src/evaluate.cpp has the commented state-of-the-art rules defined in Stockfish.


The line that you refer to is probably 1.b4 e5 2.Bb2 Bxb4 3. Bxe5 Nf6.. I recall some early opening books saying that this was a bad defence because it surrendered a center pawn. The more modern view is that Black does get a very fast development in this line which is quite dangerous. I gave up the Polish when this started to become well-known. Until then I had good results. Often I got something like a reversed Sicilian with a very useful move thrown in.
I have not kept up with recent developments but there is an article in New in Chess
yearbook 132(2019) which is where I would go to catch up.


Dana Mackenzie wrote a nice series of articles about opening statistics in 2015.
For the most drawish openings, he writes this:

The Exchange Slav (D14) dominates this category like no variation dominates any other category. It’s a unique ECO code, a variation that is more about the players’ psychology than about chess. According to Rob Weir’s tables, this variation results in a draw 79.9 percent of the time in master play, and usually quickly. (The average number of moves is 25, about 8 less than any other variation.) If anything, I think that Weir’s statistics understate the extent to which these six moves serve as a wordless draw proposal. Weir removed all games of 10 moves or shorter from his database. When I look this position up on ChessBase, it looks as if at least 90 percent of the games are draws.
The top five drawing variations:
D14 (Exchange Slav with … Nc6 and …Bf5): 79.9 percent draws
D79 (Symmetric Grunfeld, 1. d4 Nf6 2. c4 g6 3. g3 d5 4. Bg2 Bg7 5. Nf3 O-O 6. O-O c6 7. cd cd): 59.0
C92 (Ruy Lopez, Flohr-Zaitsev Variation 9. … Bb7): 57.5
D13 (Exchange Slav, not 5. Nc3 Nc6 6. Bf4 Bf5): 56.2
B36 (Maroczy Bind, side variations): 56.1

For the least drawish:

Unlike the last category, the Hall of Shame of chess openings, this category consists of the most honorable, “fightingest” opening variations in chess. And what better variation to start with than B89, the Velimirovic Attack in the Fischer-Sozin Variation of the Sicilian Defense? The above position arises after 1. e4 c5 2. Nf3 d6 3. d4 cd 4. Nxd4 Nf6 5. Nc3 e6 6. Bc4 Nc6 7. Be3 Be7. To get an idea of the fireworks that may ensue, take a look at the amazing game Fischer-Geller from Skopje 1967. This was one of the three losses that Fischer included in his My 60 Memorable Games, so you know it has to be a pretty special game.
The top five:
B89 (Sicilian Defense, Sozin-Fischer-Velimirovic Attack): 25.2 percent draws
A44 (Old Benoni, 1. d4 c5 2. d5 e5): 25.5
B00 (Uncommon 1. e4 openings, e.g. Nimzovich 1. … Nc6, Borg 1. … g5, etc.): 27.5
C05 (French Tarrasch, closed variation, including the pawn sac 1. e4 e6 2. d4 d5 3. Nd2 Nf6 4. e5 Nfd7 5. Bd3 c5 6. c3 Nc6 7. Ngf3 Qb6 8. O-O!?): 29.5
A60 (Main Variation Benoni, 1. d4 Nf6 2. c4 c5 3. d5 e6, side lines): 29.6


What are the similarities and differences in pawn Structure from the Scandinavian and the Caro-Kann?

The pawn structure in the Caro-Kann Classical Variation and the Scandinavian can be the exact same. The optimal pawn breaks are either pushing the c6 pawn to c5 or pushing the e6 pawn to e5. The differences are in the positions of the pieces, which is why far more people play the Caro-Kann than the Scandinavian. In the Scandinavian, black spends many tempi moving their Queen around, giving white time clamp down on these possible pawn breaks.


Is there any GUI for Stockfish which allows comments in macOS Big Sur?

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


Is there a chess move history app for Mac?

I believe the Scid vs PC and Xboard would do the job. They can both run on Mac.


I will assume here that you are talking about sacrificing pieces and not just pawns, which require less compensation.

For a sacrifice to work out you generally need to either 1) checkmate the opposing king, or 2) eventually gain the material back. There are other scenarios, but they're less common and I will ignore them here. Often goal 2 occurs because Black is required to give up material to avoid goal 1.

Either of those goals can be accomplished in the short term by a forced sequence that you can calculate, or in the longer term, where you don't calculate an exact sequence that will lead to your win but are confident that your good position will lead you there eventually.

Unfortunately there are not reliable quantitative compensation metrics such as "an exposed king is worth two pawns". Long-term sacrifices are generally made on intuition, which improves as one gains experience. There are some decent rules of thumb, though. Here are some good signs that your attack may succeed:

If you have two more pieces attacking his king than he has defending it.
If you are down a piece, but currently have more pieces actually participating in the game than he does (for example, both your rooks are active, but he still has one on a8 blocked in by a knight on b8).
If it is difficult for him to route his pieces back to defend his king.
If it is difficult for his king to run away (often the bottleneck is at f8).
If you have certain configurations of pieces (e.g., a knight on the sixth rank supported by a pawn, or doubled rooks on an open file) that are more valuable than you'd expect purely from their "point value".
If the king's pawn cover is broken, or if he is stuck in the middle of the board.

If, say, you can sacrifice a piece for a pawn and three of the above conditions apply, that is a good sign that the attack will succeed at one of its two general aims. But it all depends on the actual position.


As can be verified by looking at player information on http://uschess.org, RSUPP_YR and RSUPP_NUM are the year and month of the latest supplement with a rating for that player (which is in the R_LPB_RAT columns). If you looked up a sample player who has a P in R_PLR_TYP, it wouldn't be hard to confirm whether that means that the rating is provisional.


The move 4... c5 is good because:

It is thematic in the Queen's Gambit Declined to break with either ...c5 or ...e5. With 4...c5, this is done without loss of time
White isn't putting pressure on the centre, so Black can take it

Here is a sample game, which ended in a draw, between top players Karpov-Sveshnikov

[FEN ""]
[White "Karpov"]
[Black "Sveshnikov"]
[StartPly "8"]

1. d4 d5 2. c4 e6 3. Nf3 Nf6 4. e3 c5 5. Nc3 Nc6 6. cxd5 Nd5 7. Bb5 cxd4 8. Nd4 Nc3 9. bxc3 Bd7 10. O-O Nd4 11. Bd7 Qd7 12. cxd4 Be7 13. a4 O-O 14. Qb3 Rfc8 15. Bd2 Rc6 16. Rab1 Rb6 17. Qa2 Ra6 18. a5 Bd8 19. Qb3 Ba5 20. Ba5 Ra5 21. Qb7 Qb7 22. Rb7 Rc8 23. Rfb1 g6 24. h3 Rc2 25. R1b2 Rb2 26. Rb2 Ra1 27. Kh2 h5 28. g4 hxg4 29. hxg4 a5 30. g5 a4 31. Rb8 Kg7 32. Ra8 a3 33. Kg3 Rg1 34. Kf4 Rg2 35. f3 a2 36. e4 Kh7 37. Ke5 Kg7 38. f4 Rb2 39. d5 exd5 40. exd5 Re2 41. Kd6 Rd2 42. Kc6 Rc2 43. Kd7 Rd2 44. d6 Rc2 45. Ke7 Re2 46. Kd8 Rd2 1/2-1/2


KRPP vs KRP - maximum depth to conversion?

As Glorfindel notes,
the Lomonosov tables are great but might not have the answer you want.
In RPP/RP, according to the list in
this
article by Guy Haworth, we find that the maximal distance to mate
is 200+ moves, from the following position -- which happens not to have
the White pawns connected, but worse for your purpose,
it looks like most of the play is post-conversion:

[Title "Black to move; White eventually wins"]
[Fen "8/k1P5/8/8/1R5P/7p/r7/1K6 b - - 0 1"]
[StartFlipped "0"]

1...h2 2.Kxa2 h1=Q 3.c8=R!

after Kxa2 we're in 6-man territory, and the k4it.de site says
"Win in 216" starting Qd5+ 4 Kb1 Qa5(d6) -- that's right, not Qd1(h1)+,
which lets White win in only 200, nor Qd3+, which hastens the end
by another move (199).

Possibly Guy Haworth has enough access to 7-man tables
to get the answer to your query.


What is the highest number of pieces from one side that can be involved in a checkmate?

Here is a solution with all 16 white pieces, all mandatory for checkmate, without promoted units and without needing to protect the white king from checks. If you remove any white piece but the king, the position is still legal but not a checkmate anymore. Moving the wK to a random square (say, h1) would also destroy the mate.

QNr1R1b1/P1BpnP2/3P4/qP4Pr/Rn2kP2/1N4PB/2P2K2/8 w - - 0 1

Last move is Nc6-b8# or d5-d6#.


Approach to learning one opening and its variations?

When learning a new opening, I tend to stick to a line which suits my style. At first, I will play strictly to the book and usually end up in traps, getting a piece horribly out of position, or with a pawn structure that prevents defending myself. After a while I begin to realize the traps that are associated with the opening and can avoid those. Eventually I will have my pieces in the right alignments, usually by the 8th move or so. And after a long time, I will have become used to setting up the pawn structure so that I am well defended by the 15th move.

Once those basics are covered, I will begin to look for places in those first 15 moves where I can get in a simple tempo changer, like a bishop check, so that I can castle with tempo, or perhaps there is a nice trap somewhere. This is just me though, I am not sure how everyone fares with learning new openings or if they just pick them up right away.

An example of this situation for me was the English (1. c4 .. 2. Nc3). I really enjoy this opening, but figuring out how and when to advance the e and d pawn took me a while to learn. As did figuring out if or when I should fiancetto, or advance the f pawn after 0-0, or how to avoid a kingside pawn rush, etc.

As for the question of learning all the lines. I did not, I just learned the one which I felt was similar to my tastes, and then learned all the nuances to that one, including its transpositions to other similar lines. Sometimes I have noticed the English can transpose to the London, which I enjoy.

Specifically about the article you link, I agree that playing towards an outdated but proven trap can be beneficial, but I honestly doubt your opponent is going to play that exact line. So in the mean time, you will have to deal with all the other facets of the opening you only learned the one trap for. Note that the author states "All you need is a desire to learn new stuff.". I think that is the key to learning an opening. Learn the main line you like, and then play it for a while knowing you are going to get cheap shotted, trapped, blocked, out of position, and be in a funk while learning it. Once you get over having all that happen to you, then you will have that shiny polished diamond.


I'd say no. Playing against a human being is a lot different than playing computers. Here is an article (unfortunately, it is in Dutch) about a German player with a rating under 2100 who regularly beat the top chess programs, by playing strange openings and long-term sacrifices. This was a few years after the Kasparov - Deep Blue match.


Rating calculations for Anand-Carlsen world championship

First, note that the final ratings depend entirely on the score of the match, not on the particular games. For example, if they each win a game, their ratings will change by the same amount as if they draw both games. This may seem like a coincidence but it's just a consequence of the way that FIDE ratings work.

Here is the entire table of possible results. The columns are Anand's match score, Carlsen's match score, Anand's post-match rating, and Carlsen's post-match rating. The results are sorted by post-match rating.

  A   C  A_rat  C_rat
0.0 7.0 2749.1 2895.9
0.5 6.5 2754.1 2890.9
1.0 7.0 2755.4 2889.6
1.5 6.5 2760.4 2884.6
2.0 7.0 2761.7 2883.3
2.5 6.5 2766.7 2878.3
3.0 7.0 2768.0 2877.0
3.5 6.5 2773.0 2872.0
4.0 7.0 2774.3 2870.7
4.5 6.5 2779.3 2865.7
5.0 7.0 2780.6 2864.4
5.5 6.5 2785.6 2859.4
6.0 6.0 2790.6 2854.4
6.5 5.5 2795.6 2849.4
6.5 4.5 2799.3 2845.7
7.0 5.0 2800.6 2844.4
6.5 3.5 2803.0 2842.0
7.0 4.0 2804.3 2840.7
6.5 2.5 2806.7 2838.3
7.0 3.0 2808.0 2837.0
6.5 1.5 2810.4 2834.6
7.0 2.0 2811.7 2833.3
6.5 0.5 2814.1 2830.9
7.0 1.0 2815.4 2829.6
7.0 0.0 2819.1 2825.9

Therefor the answers to your questions are

None.
He needs to win the match with 7 points, or with 6.5 points with Carlsen scoring at most 3.5.
2895.9, 2825.9.
2819.1, 2749.1.


How to create PGN notation with wrong moves in it?

PGN files are normal text files. You can generate it to somepoint using the software and then save the file, open it in a text editor (notepad, notepad++, ...) and continue editing there.


Seeking GM-level coverage of a typical pawn structure

Vallejo has a great series (Spanish only) in chess24 about the Caro-Pirc, which covers this particular structure. Note that the dynamics of positions with those two pawn structures are probably very different from one another (a ...c5 break by Black would have a very different impact on each case. Similar ofr the pressure on the semi-open d file)
"Engine claims equality" does not make much sense when referring to the pawn structure itself, since many different factors will determine the actual evaluation of a given position.


In the pawns only, you don't need to move so many pawns.  Getting the major pieces involved early seems to be fastest:

[FEN ""]

1.e4 c5 2.Qh5 Qa5 3.Qxh7 Qxa2 4.Qxg7 Qxb2 5.Rxa7 Rxh2 6.Rxb7 Rxg2 7.Rxd7 Rxf2 8.Rxe7+ Kd8 9.Qxf7 Rxd2 10.Qf5 Qxc2 11.Qxc5 Qxe4+  *

I was unable to find a faster version of the piece only.


What algorithms and heuristics are popular in computer chess?

Algorithms mainly used are based on searching the state space. The problem is that the possible positions a piece can make in the next move is very huge. But it is finite. It is basically a search problem. There is a valid position a piece can take. That is there is a known start state and a know end state. There is no probability involved like the problem of tossing a coin.
A typical algorithm is to use brute force and compute moves for a fixed number of moves. MiniMax can be used in such cases. Alpha-beta pruning is also a well know algorithm used. Mostly the search spaces are represented using a tree based data structure.
Computer program also heavily use databases containing moves, openings, end-game positions etc.


First, black is hardly busted here, and Stockfish 11 confirms this with both 10...Be7 and 10...b5 being 0.00 at a depth of 30. 10...Bb4 is also reasonable. That said, as I force in the moves it believes are best, it eventually sometimes thinks white has a slight pull, which is not surprising given the clear space advantage. At the same time, in practice, per the Mega 2020 database, the white wins 72.3% of the time from this position, so unless you play like a computer, you still may lose, and there are a virtually infinite set of possibilities for white to play while black is walking a fine line all the way. This is a line I would try to avoid in practice, and keep out of my repertoire as a matter of course.

I do not play the Scandinavian, but I have played the Caro-Kann for a long time, and this is very similar to one of the main lines, and what I can say about both is that white has more space, and that is not going away for a while, and thus this is always a little uncomfortable for black...a typical plus-equals position. In both, black must finish development, especially securing the king here since it is vulnerable to tactics, and then eventually break back with c5. Other times, it ends up an opposite-side attack.

Most players here have played 10...Nxe5, which is horrible from both a Stockfish perspective at +1.3, and a winning percentage perspective at 82.2% for white. It is not a good move in a practical game as it solidifies white's space advantage with tempo, and puts the Bf5 at risk immediately to 10...Nxe5 11. dxe5 Nd5 12. g4 Bg6 13. f4 with a solid advantage.

You cannot get a 100% answer to your question as it is too early in the opening to say as it is with virtually every reasonable opening where white has a small space advantage. It will always feel like white has a small advantage until it eventually levels out...or doesn't. That is chess.

This is very close to equal, and super GMs would hold it, so the way I would play it is the solid 10...Be7. After that, there are basically two plans for white. To move the Bc4 to b3, playing prophylactically, or to play Rhe1, and eventually expand on the kingside.

There are an incredible amount of possibilities here, but this will give you a place to start.

P.S. In a position like this, and this one is not unique, there are so many reasonable lines that it is unclear which is best for the stronger side, and thus, there are literally millions of possibilities from the moment you play 10...Be7 in just the next few moves. In cases like this, now that you have a place to start, you will need to spend a lot of time on your own with a computer not just to get a few more specific lines, but also to get a feel for the plans and move orders that may occur. Since you cannot possibly memorize every possibility, you are almost certainly going to end up on your own sooner than later, and what you need to develop is a sense of HOW to play the position correctly.

 [FEN ""]

  1. e4 d5 2. exd5 Qxd5 3. Nc3 Qa5 4. d4 Nf6 5. Nf3 c6 6. Bc4 Bf5 7. Bd2 Nbd7 8. Qe2 Qc7 9. O-O-O e6 10. Ne5 Be7 11. Bb3 {Prophylactically avoiding b5.} (11. Rhe1 O-O 12. Bf4 Bd6 13. Kb1 Nd5 {And this is equal but for the one move I cannot imagine anyone playing.} 14. Bxd5 exd5 15. Nxd7 Bxd7 16. Bxd6 Qxd6 17. Qe7 Qc7 $14 {But it is the smallest of edges as rooks will soon be traded.}) 11... h5 $1 {Securing the Bf5 from g4.} 12. Bf4 Bd6 13. Rhe1 a5 {Equal per the computer, and with good counterplay.}

Here are some lines based on your supplemental questions in the comments.

 [FEN ""]

 1. e4 d5 2. exd5 Qxd5 3. Nc3 Qa5 4. d4 Nf6 5. Nf3 c6 6. Bc4 Bf5 7. Bd2 Nbd7 8. Qe2 Qc7 9. O-O-O e6 10. Ne5 Be7 11. f3 (11. f4 $6 {This is just too slow, and leads to black being better.} b5 12. Bd3 (12. Bb3 h5 13. Rde1 {And if the computer thinks that this is best, something has definitely gone wrong for white.} Nb6 $17) (12. g4 Nxe5 13. fxe5 Nxg4 14. Bd3 (14. Bb3 a5 $17) 14...Bxd3 15. cxd3 h5 $15) 12... Bxd3 13. Nxd3 b4 $15) (11. h4 {Again, too slow.} b5 12. Bd3 Bxd3 13. Nxd3 a5=) (11. h3 b5 12. Bb3 (12. g4 Bxc2 13. Bxe6 Bxd1 14. Bxf7+ Kf8 15. Rxd1 Nxe5 16. dxe5 Kxf7 17. exf6 Bxf6= {Up an exchange, but white has activity. It is dynamically equal.} 18. Qf3 (18. g5 Be5 19. Qf3+ Kg8 20. Qe4 {Transposes.}) 18... Kg8 19. g5 Be5 20. Qe4 Rd8 21. Kc2 Qe7 22. f4 Bd6) 12... a5 13. g4 Bg6 14. g5 (14. Nxg6 hxg6 15. a4 b4 16. Ne4 Nxe4 17. Qxe4 Nf6 $14 {White has maybe the tiniest of edges here. The Bb3 is not really well-placed.}) 14... Nd5 15. Bxd5 $1 (15. Nxd5 exd5 16. Nxg6 hxg6 17. Rde1 Nb6 18. a3 a4 19. Ba2 Kd8 20. h4 Bd6=) 15... exd5 16. Bf4 Qb7 17. Rhe1 (17. Nd3 Bxd3 18. Rxd3 Nf8 19. Be5 Ng6 20. Bxg7 Nf4 21. Qd2 Nxd3+ 22. Qxd3 Rg8 23. Qxh7 Bxg5+ 24. f4 $3 {To lure the B to a square that Qf5+ is a threat later.} (24. Kb1 $2 O-O-O 25. Qf5+ Qd7 26. Qxg5 f6 27. Qxf6 Rxg7 $17) 24... Bxf4+ 25. Kb1 O-O-O 26. Bf6 Bd6 27. Bxd8 Rxd8 28. Rf1 Rf8 $14 {But almost equal.}) 17... O-O $1 18. Nxg6 fxg6 19. Qxe7 Rxf4 $14 {But black has good counterplay against the weak pawns.}) 11... h5 12. Bf4 (12. Bd3 {The computer likes this move, but I cannot imagine that it gives white a lot.} Bxd3 13. Nxd3 b5=) 12... b5 13. Bb3 (13. Ng6 Bd6 14. Bxd6 Qxd6 15. Nxh8 bxc4 {And Ke7 next.}) 13... Bd6 14. Kb1 a5 {With complicated play for both sides that the computer says it equal.}


How should I play as White if Black Defends the Tartakover QGD without ...h6?

It depends on your own tastes, but I'd recommend not taking. Taking after ...h6 is justified because it essentially costs Black a tempo (i.e., playing ...h6). If you take without provocation then no one's losing tempi, you're just making an exchange.

If you really like trading on f6 then go ahead, but objectively you shouldn't have any advantage.


Million Base 2.5 (available from a link here) and ICOfY Base are two free options that more than meet your given criteria, each providing millions of games in PGN format to draw from as you please. In particular, ICOfY Base includes well over 4 million games.


Light chess literature for beginning kids and their parents

These two books are a good starting point, IMO.

Chess for Kids from Micheal Basman
How to Beat Your Dad at Chess (Gambit Chess)


Are there any free chess engines that can be used to analyze online or in a mobile phone?

Please specify your mobile platform in your question.

On the iOS platform, I recommend my own apps for doing that. www.smallchess.com.

Otherwise, there're lots of possibilities. If you can narrow your focus, I'll edit my answer.


Looking for an opening line: a rook vs 5 pawns

Is it this line in the Advance Caro-Kann of which you are thinking?

[FEN ""]
1. e4 c6 2. d4 d5 3. e5 Bf5 4. Nc3 e6
5. g4 Bg6 6. Nge2 c5 7. h4 cxd4 8. Nxd4 h5
9. f4 hxg4 10. Bb5+ Nd7 11. f5 Rxh4 12. Rf1 exf5
13. e6 fxe6 14. Nxe6 Qe7 15. Qe2 Rh2 16. Nc7+ Kd8
17. Qxe7+ Bxe7 18. Bf4 Rxc2 19. Nxa8 Bh4+ 20. Kd1 Rxb2


Has there been a game which was drawn with three queens?

Currently I still can't find a drawn game, but I found a game where white had 3 queens, black had 2 and other pieces, and black won. There was a game on chess.com where black had 0:00.1s left and promoted in time for checkmate (3 queens).

[FEN ""]
[StartPly "137"]

1. Nf3 Nf6 2. c4 g6 3. Nc3 Bg7 4. e4 d6 5. d4 O-O 6. Be2 e5 7. O-O Nc6 8. d5 Ne7 9. Bg5 h6 10. Bxf6 Bxf6 11. b4 Bg7 12. c5 f5 13. Nd2 Kh7 14. Rc1 Ng8 15. cxd6 cxd6 16. Nb5 Nf6 17. Nc7 Rb8 18. Bd3 f4 19. Qa4 a6 20. b5 Nh5 21. f3 Rf7 22. b6 Bf8 23. Qb3 Ng7 24. Rc2 Qf6 25. Rfc1 Bd7 26. Bxa6 bxa6 27. Nxa6 Rb7 28. Rc7 Qg5 29. h4 Rxc7 30. Nxc7 Qxh4 31. b7 Nh5 32. b8=Q Ng3 33. Qc4 Qh1+ 34. Kf2 Qh4 35. Kg1 Qh1+ 36. Kf2 Qh4 37. Kg1 Qh1+ 38. Kf2 Qh4 39. Qb6 Be7 40. Nf1 Qh1 41. Nd2 Qh4 42. Ke1 Qh1+ 43. Nf1 Bh4 44. Kd2 Qxg2+ 45. Kc3 Ne2+ 46. Kb2 Nxc1+ 47. Kxc1 Qxf3 48. Ne6 Qa3+ 49. Kd2 Be7 50. Qcb3 Qa8 51. Qc7 Be8 52. a3 Qa6 53. Qcc4 Qa7 54. Qf3 Bh4 55. Qh3 g5 56. Nd8 Bd7 57. Qhc3 Rg7 58. Nc6 Qg1 59. Kc2 g4 60. Nb8 Be8 61. Nd2 Bg6 62. Qc8 Qg2 63. Nd7 Be7 64. Nxe5 dxe5 65. Qxe5 Bxa3 66. Qcc3 Bf8 67. d6 f3 68. d7 f2 69. d8=Q f1=Q 70. Qde7 Qf7 71. Qxf7 Bxf7 72. Qf5+ Kg8 73. Qfc8 Qf2 74. Qb4 Bg6 75. Qbc4+ Kh7 76. Qxg4 Bd6 77. Qce6 Bb4 78. Qd5 Rc7+ 79. Kd1 Bxd2 80. Qxd2 Qf1+ 81. Qe1 Rc1+ 82. Kxc1 Qxe1+

(white had an advantage but didn't use it properly and hung too many pieces)


Engine recommends a move that (I think) loses a pawn

In short: White can sacrifice the pawn on a2 and will gain a quicker development of his pieces. The technical term for this is compensation.

In detail: In the current position, both sides have not developed their pieces. Getting out the minor pieces and castling should have priority.

There are no obvious weaknesses. In some lines (e.g. if white's bishop
 is on f4 or g5 and e3 has been played) white should watch out for Bb4+. Also black has an easy way to simplify/equalize the position further by playing Nc6 followed by e5 or alternatively to attack the center with c5.

Because of this it is essential to act quickly. The white dark-squared bishop probably wants to stay on c1 or d2 for the time being because of the potential threat of Bb4+ (or even Qa5+ exchanging the queens). So the most natural development moves in the position are Nf3 or e3 (making space for the bishop on f1). Either move is decent, but e3 has the advantage that the bishop can quickly go to c4 where it attacks the queen on d5 (or a2 if black takes the pawn).

Looking at the concrete line 1. e3 Qxa2 2. Bd2, you note that white has made two development moves while black has won a pawn but the black queen is somewhat far from the action and in fact is in danger of running out of squares: white is threatening for instance Qc2, Bc4 which would win the queen).  Likely black would have to make another queen move retreating the queen to d5 or e6, losing even more time for development.


What is the process for amending the rules of chess?

FIDE has a Rules Commission (https://rcc.fide.com) which reviews the Laws of Chess every four years according to their FAQ. I don't know about the process itself, but if I had to guess I'd say it involves lots of committee meetings and emails. :-) One interesting detail, though, is that they have a form you can fill out with suggested changes to the Laws: https://rcc.fide.com/form-of-loc-change-proposal/
But like the FAQ also says,

Considerable changes were made in the 15th century. The scope of the queen and bishop in particular were increased then. This made it a much faster game. The Laws are reviewed every four years, but these are either just tidying up, or changes to the Tournament Rules.

So don't expect any changes to things like how the pieces move, other than possibly closing of loopholes like the one about vertical castling which you mentioned (are there any loopholes left? That's a separate question).


I'll try my best to answer this rather ambiguous question however I'd like to note that if you want help in chess your best bet is to familiarize yourself with terms like "tactics", "strategy" and so forth.

A little bit on 3 major terms in chess, or at least how I perceive them to be:

Tactics

patterns in chess(calculable) that lead to something factual such as winning a pawn, winning a piece, mating and so forth. Usually a forced sequence of moves.

Strategies

Really just the general plan you're following. If you try to pressure a certain square or use a sequence of moves to go on the offense and had that as your plan that's an implementation of a strategy.

Positional play

The most ambiguous term, it's generally just logical chess; Knights are strong in the center so you'd play your knight there if you had the opportunity. You don't follow a particular strategy nor did you calculate variations to see if this knight will lead to a definite advantage but because experience and general chess knowledge dictates knights are strong in the center you can conclude there is no downside to having it there, the opposite even.

All these terms can become moot easily, miscalculations, positional play that's not backed up by proper think-work and strategies that become invalid due to the opponent playing out his own game... You get the point.

So what we're looking for here is the term tactics, the pure act of seeing forceful moves that lead to a certain advantage. Tactics are something usually gained through practice and lots of experience, it also helps when you are familiar with the basic mates(mentioned before like King+Queen, King+rook, and King+2xbishop or King+bishop+Knight if you're feeling really up to the task) but also mates that simply involve certain patterns. Here's a supersimple one but you get the idea:

1K6/PPP5/8/8/8/4r3/3k4/8 b - - 0 1

There's a few ways to practice tactics:

Books

Books that involve endgames will always be great, they involve a great deal of tactics and will surely strengthen your ability to see them throughout the entire game.

Chess puzzle books are another great idea.

Websites

Let's not forget this great resource called the internet, there's websites out there with tactics trainers designed to take in account your playing strength as you do their puzzles. Two of these I'm aware of are:

www.Chess.com
www.Chesstempo.com

Especially Chesstempo is a great resource.


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

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


Why did this guy resign, was there a strategic reason?

White's threats revolve around Nxa7. What can Black do? This is the line given by Ubisoft's Chessmaster:

2r1r1k1/pb1n1pp1/1pq2n1p/1N6/1P1B3Q/P2B1R2/2P3PP/3R2K1 b - - 0 1

1... Ra8 {Directly defending a7} 2. Rg3 {Threatening to take on h6} Kf8 {Breaking the pin} 3. Qf4 Nh5 {This forces white into the sacrificial line that follows} 4. Bxg7+ Nxg7 5. Nd6 {Threatens 6. Qxf7#} Ne5 6. Qxh6 {Sure, Black has a piece for 2 pawns, but White's attack is too strong}


What is White's main plan in Sicilian Keres variation?

Disclaimer: there might be other ideas too.
I used to play this some time ago against sicilian. My idea was that I liked closed sicilian positions (2. Nc3) if black did not play the "main" setup against it (that is, 2. ... Nc6, 3. ... g6 etc). So with Ne2, I still could play the closed variation against, for example, 2. ... e6 and 3... d5, and after 2. ... a6, but if black replied 2. ... Nc6 I could play 3. d4 ( or 4. d4) and return back to the "open", more sound sicilian. What white gains is a little bit of flexibility, and a chance to confuse the opponent if black has an inconsistent repertoire. I knew one guy who played d6-a6 setup against open sicilian and e6-d5 against closed one, so Ne2 was very confusing against him.


Program that will give all available moves given the state of a board, including check

You seem to be writing a move generator.

Conventionally, a set of legal moves is generated by first generating a list of pseudo-legal moves (i.e. all moves which could be made, ignoring the fact that the king needs special treatment) and then filtering out moves which leave the king in check.

The legal move generator in Stockfish (one of the strongest chess engines) does exactly this - moveList is initialised to a list of pseudo-legal moves, which is then iterated over to filter out illegal moves with pos.legal.

You can implement the detection of legal moves by simply 'making the move' (creating a board state after the move) and then checking if any piece attacks the king, though of course more efficient implementations are possible.


Capa's books are very good for your level especially the one you mentioned.
My System is probably too advanced for where you're at. It's a great book but probably better for someone around 1800. Beginners should focus on not making huge tactical mistakes. Positional play like My System teaches you how to plan what to do when you can play a game without making huge mistakes.
I don't know the other one but judging by the title I would say it's way too advanced. You won't be able to understand hypermodern chess until you have a crystal clear understanding of classical centers. Few players below 1800 have any clue what they're doing in the center.
As far what I would recommend-
I really like the book Learn Chess: A Complete Course by C. H. O'D. Alexander. I admit the book can be a little hard to read but it covers every aspect of the game and includes hundreds of tactical puzzles. The chapters on attacking are the best I've seen outside of Vukovic and are targeted towards beginner players.
Silman's Complete Endgame Course: Yes, it's an endgame book but you will learn exactly what you need to know for the level you're at. Endgames are also good for beginners because you break the game down into smaller parts and learn to use the pieces individually.
How to Play Good Opening Moves by Mednis- The book is small but i promise you you can reach 2000 without knowing anything more about the opening than what's in that book. Center, development, king safety. That's all you need to know.
Any tactics book. If you do tactics problems you will get better. Probably the book that will give you the most "bang for your buck" is How to Beat Your Dad at Chess. The tactics are common and the section on facing a strong opponent is good advice.
I'll add one more and that's Rapid Chess Improvement by de la Maza. You can buy the book if you want but the book was based on a couple of articles written by de la maza which are still freely available on the internet (search 400 points in 400 days .pdf etc) Most of the rest of the actual book is testimonials and maybe a little elaboration in some areas. Basically, de la Maza argues that you need to study tactics and develop an effective thinking process to improve from beginner to intermediate. You won't find a strong player anywhere who disagrees with that even if they don't like de la Maza.


If the white king reaches one of the green key squares, then white will win. There is no rule determining those squares, just concrete analysis. However, once we have the key squares in place, we can systematically search for pairs of corresponding squares.

If the white king is on d8, then the black king must move to f8.
If the white king is on d7, then the black king must move to f7.
If the white king is on d6, then the black king must move to f6.
If the white king is on c8, then the black king must move to e8.
If the white king is on c7, then the black king must move to e7.
If the white king is on c6, then the black king must move to e6.

If at any stage black to move has the king already placed on the square corresponding to the square of the white king, black is in zugzwang and will lose.

This example turns out to be a quite simple case of (distant) opposition and 1. Kb7! wins for white.


Why is f4 considered as bad in the opening?

It is not really possible to answer this generally as chess is more complicated and it really depends on what black is playing whether an early f4 is good or not.

I guess, what you actually like is the combination of e4 and f4. There are many examples where f4 is perfectly playable, such as in some Sicilians, the French defence and other semi-open games.

In open games (1. e4 e5) playing an early f4 tends to be somewhat dubious at the highest level, but is of course perfectly playable at the club level.

If you want a system opening with f4, why don't you play the King's Indian Attack, where "f4" is often ok whatever black does?


Anyway you cannot prevent someone avoiding the Grunfeld by move order. For instance, 1.c4, Nf6; 2. Nc3, g6; 3.e4, and it's done with the Grunfeld. The trick is it is better to play Grunfeld and KID (Bologan's KID book has a chapter devoted to this, i think) complementarily, even against the fianchetto variation. Quality chess books by Avrukh on the grunfeld are excellent, so are also The safest grunfeld and in a lesser measure Dembo's (but not bad at all). I think there is no other way out. You could also listen to Svidler's lectures on chess24, they are excellent.


Material for knowing more about Cylinder Chess

There exists several books presenting quickly various variant of chess, here is one example :
http://www.barnesandnoble.com/w/fairy-chess-books-llc/1103593111?ean=9781157372424

About learning strategy or opening theory, both of this concept require a lot of experience and games to be played. For instance in classical chess we had to wait centuries before such thing become available. A first step is to watch games played by the best players. A world championship and tournaments are organized by The Circular Chess Society :
http://www.circularchess.co.uk/

Also, it should be decent training to practice with exercises, many studies has been created with this variant of chess, here is one example :
http://www.mayhematics.com/v/cylin.htm


Reference for good French Defense games?

First, you need to narrow down your scope a bit. The French Defense has a massive amount of theory and you only need to learn a small portion of that to play it competitively.

You'll most commonly face 1. e4 e6 2. d4 d5 3. Nc3. Here, there are two main choices: 3... Nf6 and 3... Bb4. From an openings database or explorer (here, for example), you can pick the one you prefer. Notice the "Notable Games" section of the interface. These games are usually thematic and will teach you a lot about a variation with careful study. The black players are also more often than not "heroes" of the given opening, and you can look through more of their games.

Starting out, I would avoid only looking at the games of modern players. This tweet by Garry Kasparov illustrates the problem with that nicely, in my opinion. You don't need cutting-edge theory to play the opening well, you need the core ideas. These were fleshed out in the games of classical masters.

There are other lines that you need to learn as well. I commonly face the Exchange French, the Advance French, and the Tarrasch French in tournaments, and sometimes other variations. You need to know a little bit about each of these. The same process should suffice.

Apart from looking at games, I learned a great deal by reading The Flexible French by Viktor Moskalenko. The expanded version is available here.


Does ECO openings classification have an established more detailed specification - by sub indexes?

A particular ECO index might split further into sub-indices like B33a, B33b, B33c, etc. The number of such sub-indices varies (maybe it goes up to y, or only to t, or ...), and some indices don't have any sub-indices. As for a place where these are well-documented, the free database program Scid does a great job. It automatically tells you what ECO classification you are in as you view/enter a game. More than that, though, you can bring up its ECO Browser that offers a summary of the ECO code you're in if you want to see the sub-indices laid out.

For instance, when I opened Scid and entered the moves 1.e4 c5 2.Nf3 Nc6 3.d4 cxd4 4.Nxd4 Nf6, the info panel below the board indicated that we had entered into ECO index B33a. That text is clickable, and doing so brought up Scid's summary for ECO B33, complete with variation names and clickable lines (which will bring the final position up on the board), as seen in the following image:


What length of time should one spend looking for a combination, and what factors should one consider?

That's a very general question that I don't think you will get a solid answer for. The chance of a powerful combination being available depends largely on the pieces each side has available and developed. So the answer varies based on what stage the game is in and the positions of each side.

Instead I would focus on identifying the types of combinations you are comfortable with, and start to learn to identify boards where those combinations MAY be present, and others where the combinations is not present. If you can speed up your identification you can determine on the fly how much time to spend on evaluating each potential move.


Opposite colored bishops endgame: Is this a draw?

I disagree that it is a draw. In practice, it might not be a good practical decision to trade the rooks there if you are not sure it is a win, but it was almost certainly a win.

Despite the opposite-colored bishops, you are up two pawns, but more importantly, and the reason it is still a win, is that the black pawn is on the h-file, and the unbalanced pawns make this untenable for black. If it had been on the f-file, I would agree that it was a draw. It also helps that you can play the K to d3, then f4, e4, and e5.

In opposite-colored bishop endings, the stronger side wants to keep the pawns on the opposite color of the bishop to control both colors, making it easier to bring the king up and help the passed pawns advance; while the weaker side, black here, wants to keep the pawns on the same color of his bishop trying to use the dark squares to blockade. That is just not possible for black to accomplish here.

This is not every possible line, but I used a lot of endgame experience on the master level to try plans that would make some sense, and after the first few moves bringing the kings up, all the Stockfish evals are at least +5, and shortly after, they go to +9, which indicates a guaranteed win. I stopped all the analysis below when it got to +9 or greater.

 [FEN "3r3k/2p2B1p/1b4p1/4R3/3P4/4P1P1/5PP1/6K1 w - - 0 1"]

 1. Re8+ Rxe8 2. Bxe8 Kg7 3. Kf1 Kf6 (3... g5 {Trying the plan to put the pawns on the dark squares.} 4. f4 h6 5. Ke2 Kf6 6. Bc6 gxf4 (6... Ke6 $2 {The evals here are already +9.} 7. Kd3 Kd6 8. Ba4 Ba5 9. e4 Be1 10. f5 $18) 7. gxf4 Kf5 8. d5 Ba5 9. Kf3 $18) 4. Ke2 Ke7 (4... c5 5. d5 Ke5 (5... c4 6. f4 Kf5 7. Kf3 c3 8. e4+ Kf6 9. e5+ Ke7 10. Ba4 $18) 6. Bc6 g5 7. f4+ Kf5 8. d6 gxf4 9. gxf4 c4 10. Bd5 c3 11. Kf3 Kf6 12. Bb3 Bc5 13. e4 $18) 5. Ba4 Kd6 (5... g5 6. f4 h6 7. Kd3 Ba5 8. e4 Be1 9. f5 Bxg3 10. e5 $18) 6. Bb3 {To prepare d5 should black play c5 trying to trade the pawn off. This only works because white has a pawn on f4.} h6 7. f4 Ba5 8. e4 $18

Supplemental analysis of the game based on Quintec's request below.

 [FEN "3r3k/2p2B1p/1b4p1/4R3/3P4/4P1P1/5PP1/6K1 w - - 0 1"]

 1. Re8+ Rxe8 2. Bxe8 Kg7 3. Bc6 {There is no harm here, but you should really get in the habit of centralizing your king early in the endgame.} Kf6 4. Kf1 h5 $4 {In opposite-colored-bishop endings, these belong on the other color trying to setup a blockade. Here g6+h5 are just targets.} 5. Ke2 {Not bad, but f4 again with the possible line.} (5. f4 g5 6. Ke2 Ba5 {Or any move really.} (6... g4 $4 7. Be8 $18) (6... Ke7 7. Kd3 Ba5 8. e4 Be1 9. e5 Bxg3 10. f5 $18) 7. Be8 h4 8. gxh4 gxh4 (8... gxf4 9. exf4 $18) 9. e4 $18) 5... g5 6. Kf3 {Still f4.} Ba5 7. Be4 {There is nothing wrong with this in terms of spoiling the position, but it is clear that you are already headed down the wrong path.} Be1 8. Ke2 Bb4 9. f3 $2 {The wrong idea.} Bd6 $2 (9... c5 {The best try, and already close to drawing, but not quite. Even in the closest line, black will need to play perfectly, and know endgame theory.} 10. d5 (10. dxc5 $2 Bxc5 11. f4 Be7 {The only move per the computer, and the hidden point is that the Be7 will need to be able to take on h4 soon.} 12. Bc6 Ke6 13. Kf3 h4 14. gxh4 gxf4 15. exf4 Bxh4 16. g4 {With a tablebase draw.}) 10... Ke5 11. Bg6 {And there, that bad move h5 comes into play.} h4 (11... Kxd5 12. Bf7+ Ke5 13. Bxh5 c4 14. Bg6 Bc5 15. f4+ $18) 12. gxh4 gxh4 13. f4+ $1 Kxd5 14. Bf7+ {And the two passers decide.} Ke4 (14... Kd6 15. Bc4 $18) 15. Bc4 Ba3 16. Bb5 Bc1 17. Bc6+ Kf5 18. Bd5 Kg4 19. Kf2 Kf5 (19... h3 20. Be6+) 20. Kf3 Kf6 21. e4 $18 {You can already see how much more difficult this ending became.}) 10. g4 $4 {This gives away the win. Note that had they been same-colored bishops and both had dark-squared bishops, both sides WOULD want them on light squares.} hxg4 11. fxg4 Bg3 $2 (11... c5 {Immediately draws.} 12. d5 Ke5 {And the blockade is complete.}) 12. Kf3 Bd6 13. Bf5 Ba3 $2 (13... c5 14. Ke4 cxd4 15. exd4 Ke7 {Again with a blockade and draw.}) 14. e4 Bb2 (14... c5 {Now, it is too late.} 15. e5+ Ke7 16. d5 $18) 15. e5+ Ke7 16. Ke4 {It is still a draw here, but white has made progress compared to the easy draws earlier. Now, c5 is ruled out for the foreseeable future.} Bc1 17. Bc8 Bd2 18. Kf5 Be3 19. d5 Bd2 20. Bb7 Be3 21. Bc6 Bd2 22. Ke4 Bc3 23. Bb5 Bb2 24. Kf5 Bc1 25. Ba6 Bd2 26. Bc8 Bc1 27. Be6 Bd2 28. Ke4 Bc3 29. Bg8 Bb2 30. Bh7 Bc3 31. Bg6 Bb2 1/2-1/2


Is this case considered an ambiguity or not?

While it's not ambiguous (only Nfe3 is legal), it is better to be specific with Nfe3.  Successful software can deal with both Ne3 and Nfe3, but not every pgn parser is perfect, and some beginners will appreciate the additional guidance.


Strategy according to the pawn structure in the Caro-Kann

I (1878 rating) play the Caro-Kann and its cousin the Slav a lot and have found that in the Advance Variation, where White plays e5 you have to counterattack on the Queenside, usually beginning with ...c5 or ...b6 if c5 is occupied by White. You have to get the move in relatively early - usually soon after developing your QB, KN and QN. Of course, White playing Qb3 or Nh4 or Bd3, etc. can delay doing it, but it's almost always necessary to attack White there near the base of his Pawn Chain.
In some cases, White supports the Q-side so much that you can attack the neglected K-side with an ...f6, etc.
When I play White against the Caro-Kann, I play the Panov Attack or the Exchange Variation so the game is more open and Black isn't able to build the awesome wall you show in your boards. When I play Black I love it when White plays 3 e5.
If you look at chess.com/explorer (free membership may be required), click the drop-down box where "Master Games" is, select "Other Player, enter MickinMD, select Black, and click on 1 e4, you'll see it has 23 games where I played 1...c6, winning 39%, drawing 26%, and losing only 35% to White against players averaging even with my rating including excellent players from Russia, Hungary, and other chess-loving nations - one was the former high school champ of Sidney, Australia.
I posted one 3...e5 game on chess.com's Game Showcase that I won with a struggle - a struggle partly due to not playing ...c5 until later than I should have, according to some excellent players who critiqued the game at my request.


Obviously, white can't win. Let white do any move except g5+ (Kh5, for example)
65... g5 66. fxg6 Kg7 Now black bishop will move on squares c5 and g1 and white can't do any progress because pawns are blocked.

Moreover, I like black's position more,


What happens if a player makes an illegal move and nobody notices?

The FIDE laws of chess state:

  If during a game it is found that an illegal move, including failing
  to meet the requirements of the promotion of a pawn or capturing the
  opponent’s king, has been completed, the position immediately before
  the irregularity shall be reinstated. If the position immediately
  before the irregularity cannot be determined the game shall continue
  from the last identifiable position prior to the irregularity. The
  clocks shall be adjusted according to Article 6.13. The Articles 4.3
  and 4.6 apply to the move replacing the illegal move. The game shall
  then continue from this reinstated position.

So basically the game should be reverted to before that move, using the game record.

Edit: These are for standard play. Other time controls have different rules, and although most national federations basically just apply the FIDE rules, they can sometimes be different.