How long does it take to use opening preparation at top level?

As Brian noted, theory can move on quickly, but that does not remotely mean that everything that was prepared is lost in a short period of time. I think that the biggest issue was just that prepping for the world championship was much more intense, and rigorous, so Ju is going to be that much more prepared, and thus, a much more dangerous opponent than usual for while, but not just because of opening preparation.

On the other hand, I disagree that just because they have outstanding memories, that they do not forget much...virtually all memories do fade, and it can take a long time to use some prep. There is also the enormous volume that they have to memorize compared to a club player. They certainly do not forget the basics, but it is easy to transpose a couple of moves when you are already deep into the opening. I have read about this happening many times, and in the first round of Tata Steel 2020 just last month, it happened to Vladislav Kovalev in the first round versus Alireza Firouzja, and Kovalev went down without a fight (he played 16...c4? when he needed 16...Nd7 17.Ra3, and only then 17...c4). It can happen to the very best: Here is a tweet from Caruana talking about Magnus forgetting his prep. They memorize SO much that it is still human to forget things that they have not looked at for a while.

It can also take years sometimes to be able to use an opening surprise. I remember reading on at least one occasion, it took Kasparov years to use some prep, and I have heard numerous such stories about top players in my 40 years of tournament chess. Here is a link to a story about Kaspy waiting years, and using some prep against Michael Adams. That game can be found here, and 14.Qh4 was the novelty.

I also think that there is another huge factor that Humpy did not touch upon, and that is that when you play a major round robin (relative to your rating), or in this case, a world championship match, it is so intense, and the level of play is so high, that you usually come out much sharper than normal. I played a couple of round robins against all strong masters, and I felt like I was better than ever when I was done each of them.

Of course, professional players at this level continue to work on their openings, maybe daily, but it is doubtful that it is quite as intense as when she was preparing for the match. In essence, she still stays fairly booked up at all times.


First of all: Don't take engines so seriously! 0.22 is not a big drop, especially if your move suits you.

On the other hand, in order to get better, you should play more aggressive and complex lines (also that is what chess engines do), because it will expose you to some important ideas. Your opening system satisfies neither of these criteria.

Just stop avoiding main lines. Yes, they are full of theory, but you can learn from them a lot.

You are a 1. d4 player, so I would definitely recommend you not to play Nc3 before c4. I know that 2. Nc3 is a playable system, but it won't do much for your improvement.

Now to the games:

In the first game you need to understand that black is playing badly (obviously the first move is horrible - doing nothing for development and weakening his own king).

Therefore if you want to punish him, you need to play more forcefully, either the engine move 3. d5 or simply fighting for the center with 3. e4.

You don't have to worry about these pawns too much, because you're actually ahead in development and it will take black a lot of time to start attacking them. In the meantime black's king might be already mated...

Secondly, these pawns are in the center and only help you to grab more and more space. They should be moved in the opening and occupy the central squares.

In the second game, black played quite normally. So when you play these unambitious moves, you risk giving up all your opening edge as white (and you might even end up being worse).

But again that drop in engine assessment isn't that important.


To be frank, chronological order is not really a chess thing as much as a general thing that is just defined by English.

In 40 years of playing, and reading (at my peak, I had 1800 chess books, and have read 300 cover to cover), that is the first time I have heard the term "chronological order" attempted to be used as a pure chess term.

So to be clear, what I am saying is that it is not a standard chess term, however, it is a common general English term (speaking as a native English speaker) that can be applied to chess or anything else. The person, who wrote that was just using common English lexicon, not common chess lexicon, and it does, indeed, mean "the order in time that you do things".

P.S. To back this up, I also just searched 615 digital chess books, and "chronological order" was found in 20 books, however, after looking at every one of them, and how it was used, it was just used to describe layouts of the material in the book....still not as a pure chess term.


Algebraic to coordinate notation converter

Java:  https://github.com/bhlangonijr/chesslib/tree/master/src/main/java/com/github/bhlangonijr/chesslib

C++:  https://github.com/alexmdc/chesslib

Python:  https://pypi.org/project/python-chess/

C:  https://sourceforge.net/projects/sankit/

These are all able to return long algebraic notation.  Stockfish is reported to also.


Looking at the problem as if the black King is currently invisible...

gxf8=Q#
All squares are now covered. So where ever the black King is hiding, the game is over.


Simul in which the GM has to make identical moves

If I understand your proposal, I think that the constraint that you are imposing would make it too easy to defeat the poor GM. Let's imagine the following pair of games with the GM playing Black:

1. e4 e5
2. Qh5 Nf6
3. Qxf7#

1. e4 e5
2. Qf3 Nf6
3. a3

Qxf7 on the first game is "checkmate" because even though Black would simply capture the queen in a normal game, they can't do it here because they can't make the same move on the second board.


The position shown in board 2 is not a checkmate, as you correctly say.

The book is not completely clear here. The sentence "Checkmate with Queen and King" is only the task of an exercise: you have to set up the position you see on a real board, and move the pieces trying to checkmate the black king using the white Queen and King. The checkmate is not there yet, you have to play and find it. It is not immediate, it will take some moves.


Actually, nevermind about my question, because I have just found an answer myself. Just click on stop, and then click the lock button. To start again, just click on the lock button to unlock it.


Thanks for your compliment about pgn-extract (I am its author). You might be able to make the task a little easier by adding --linelength 1000 to the argument list in order to get each game on a single line, then use sed to add an unknown result to the end of the game and re-process the game with pgn-extract to add an empty 7-tag roster. Finally, use sed again to edit the White and Black tags.
The resulting command would look something like the following, although sed experts might be able to clean it up a bit:
pgn-extract -t filter_for_naked --noresults --notags --nocomments --noduplicates -bl20 --linelength 1000 my.pgn | sed -e 's/..*/& */' | pgn-extract -7 | sed -e 's/White "?"/White "AnonW"/;s/Black "?"/Black "AnonB"/' > naked.pgn

You will get some error reports for games that end in mate having inconsistent results but you can hide those in a logfile.


How do I determine who has white or black?

White always moves first. To determine who plays white in a friendly game, you can:

Toss a coin
Roll a dice
Play an even number of games, alternating sides
Play rock-paper-scissors
One player takes a white pawn and black pawn, and secretly places one in each hand. The other player picks the hand and therefore the colour to play
Use any other agreed method

In tournament play, who plays which colour is determined by the organisers and you should be informed of which colour to play before each game. If you are unsure, ask an arbiter or an organiser for clarification.

Please note that the initiative is a specific chess term defined below:

  Initiative in a chess position belongs to the player who can make threats that cannot be ignored.

Source: Wikipedia


How good can you get at bullet chess without playing standard?

I think that bullet is a skill that is half chess, but half is simply the ability to think and move quickly, which is the domain of young people. Yes, you can clearly get very good at it relative to your standard level of play. Your ratings seem to prove that.

I still question whether bullet is really good for your chess on a deeper level, but you do not seem to care about that, so if you are having fun, by all means, enjoy it. Nevertheless, this may still ultimately make you plateau permanently since bullet is very shallow in terms of depth of understanding. Plateaus vary from person to person, so just how good you can get will ultimately be something that you will have to just play and find out where you stand.

If you ultimately want to improve your depth of understanding, you do not have to choose between sitting there for hours, and bullet. You can play more using controls that are more of a happy medium.


Tools specifically for training at finding loose pieces?

I don't know of any such tool. A paid membership at ChessTempo might allow you to filter problems for the hanging piece motif. Not exactly the type of tool you imagine, but something comparable.

However I would argue against the usefulness of a tool that you describe for the following reason.

If I play chess (and I presume most other players beyond beginner level as well), I do not scan the board after every move for attacked pieces, which is what you are trying to train.

Instead I ask myself: "What did the last move change with regard to attacked pieces? There are only a few things that change if you move a piece:

the piece will attack new squares from its new position
the piece will stop attacking some squares that it used to attack on its old position
moving the piece can open lines/diagonals for other pieces to attack something
moving the piece can block lines/diagonals for other pieces

Of course, a move can also interrupt you from defending a piece or can create all kinds of multi-move tactics. You don't need to learn a new way of thinking to include these, as you advance in chess: just rephrase/generalize the question to: "What did the last move change with regard to the position?" Anyway, for the time being let's stick with attacked pieces which is what your question is about.

If you look a bit more careful you will soon recognize some features of chess pieces which make answering the question easier. For instance if you move a rook horizontally, it will still attack squares along the line that you moved it, however all the squares that it attacked vertically change. Similarly for the bishop: if you move it along one diagonal, it will essentially only change things along the other (perpendicular) diagonals.

Also, you can take into account the range of pieces to quickly assess whether something is getting attacked. For instance pawns are very short range and it is very easy to see whether they attack anything. Similarly if your opponent does some moving around far away from any action, behind his pawn chain (e.g. castling), chances are that this does not attack anything new.

So my recommendation would be to go with an incremental approach, storing the attacked pieces (later you will add all possible tactics/strategies) in your memory and update your memory after every move.


How can I use stockfish to find good moves, instead of just bad moves?

Sorry, computer engines are not designed to think like a human. It's a machine, it's written to play strong chess. There is no intelligence in there to think like that.

The "good moves" you mentioned were actually bad moves at Stockfish's level.


Why do you put a knight or pawn in front of a fianchetto bishop?

This is a typical Sicilian Dragon position.  The fianchetto Bishop controls the long diagonal which helps protect the King, by protecting the h8 square and providing luft, and attacks the opposing King.  The Bishop is able to control two center squares while one posted on c4 can only control one center square.
The Knight does currently obstruct the Bishop, but can move with devastating effect, Nxe4 uncovers an attack on the d4 Knight.  In lines where there is a Pawn blocking the Bishop, King's Indian Defense/Attack, the Pawn is pushed to release the Bishop or the Pawn is used for a kingside attack.  The Bishop is often in the way of the Rooks, but does still provide good defense for the King.

[fen ""]
1. e4 c5 2. d4 cxd4 3. c3 d3?! { (0.00 ? 0.75) Inaccuracy. Best move was dxc3. } (3... dxc3 4. Nxc3 Nc6 5. Nf3 e6 6. Bb5 a6 7. Qa4 Qc7 8. O-O Nf6 9. Re1 Ng4 10. Bxc6) 4. c4?! { B21 Sicilian Defense: Smith-Morra Gambit Declined, Dubois Variation (0.75 ? 0.15) Inaccuracy. Best move was Bxd3. } (4. Bxd3 Nc6 5. Nf3 Nf6 6. O-O e5 7. c4 Bc5 8. a3 a5 9. Nc3 O-O 10. Bd2 d6) 4... g6 5. Nc3 Bg7 6. Qxd3 Nc6 7. Bf4 d6 8. O-O-O Nf6 9. Bg3?! { (-0.24 ? -1.12) Inaccuracy. Best move was Qd2. } (9. Qd2 O-O 10. Nf3 Be6 11. Kb1 Qa5 12. Ng5 Ng4 13. f3 Bxc3 14. bxc3 Nge5 15. Nxe6 Qb6+) 9... O-O 10. f4 Qa5 11. Kb1?? { (-1.06 ? -7.19) Blunder. Best move was a3. } (11. a3 Nd7) 11... Nb4 12. Qd2?? { (-6.81 ? -12.80) Blunder. Best move was Qe2. } (12. Qe2 Nxe4) 12... Nxe4 { White resigns } 0-1

The Bishop plays a secondary role.  By controlling the long diagonal, it does support the attack.
By looking at Dragon games, especially Rxc3 sacrifices, you will find that the Bishop is excellent at attacking along the long diagonal.


Why did Gelfand resign against Anand in the shortest match in WCC?

http://www.chessgames.com/perl/chessgame?gid=1666558 the shortest game is World Championship history.  It's not so much the material difference, after Bd3 Qxb1+ two Rooks is not enough for the Queen and the Bishop, but the weakness around the Black King will cause Gelfand to lose anyway.  After h6 and Ne4, d6 will fall and mate is always possible on g7.  A thorough annotation is at http://www.ajschess.com/lifemasteraj/FIDE_World-Champ-2012_game-eight.html

[fen ""]

1.d4 Nf6 2.c4 g6 3.f3 c5 4.d5 d6 5.e4 Bg7 6.Ne2 O-O 7.Nec3 Nh5
8.Bg5 Bf6 9.Bxf6 exf6 10.Qd2 f5 11.exf5 Bxf5 12.g4 Re8+ 13.Kd1
Bxb1 14.Rxb1 Qf6 15.gxh5 Qxf3+ 16.Kc2 Qxh1 17.Qf2


Why is algebraic notation called algebraic?

I think that Jonathan Garber is right. Much of algebra has to do with equation in an x y coordinate plane which is very similar to the way that algebraic notation denotes specific squares on the board. I have however not been able to find any specific source of the information.


What are some physical chess simulators?

Do you mean?

  https://www.youtube.com/watch?v=qS5EPbsmCXs

I don't know how you'd get his robot, but it won't be affordable.

Have you seen this page?

  https://chessprogramming.wikispaces.com/Robots


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

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

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


There can be no one-size-fits-all as to how to prepare for an opponent, as this will depend greatly on the playing strengths of both the one preparing and the opponent, and what works for one person won't necessarily work for another. So I'm somewhat hesitant to answer at all, but I'm hoping that the following three vignettes of chess preparation will shed a little light on the matter for you, without being blatantly inaccurate or overly biased.

1. Bobby Fischer prepares for Boris Spassky. Leading up to the 1972 world championship match, Fischer famously immersed himself in a deep study of all Spassky games he could get a hold of, going as far back as he could, to the point that he basically knew all Spassky games on record inside and out. (See e.g. the mention and footage of his "big red book of Spassky" at 8:10 of this 60 Minutes report from 1972. The video's a little hazy, but you can make out that the book is Weltgeschichte des Schachs 27: Spassky.)

For someone of Fischer's prodigious talent and understanding, this kind of focused study could yield extremely useful insights in terms of both (1) concrete opening preparation for the match, and even (2) uncovering particular strengths/weaknesses in Spassky's middlegame and endgame play.

This is all well and good for grandmasters, as such particular preparation can be the best use of their time, especially as they necessarily have very strong general skills already. Most of us mere mortals, however, wouldn't be able to reap the same benefits from such an in-depth study of an opponent, for the simple reason that we don't understand enough about chess itself to truly glean much useful information from all that study, and besides, our time could be more efficiently spent improving our overall game. As to the specifics of preparation at that rarefied level of play, well, "whereof one cannot speak, thereof one must be silent."
Nevertheless, here's an account of my own very limited personal experience down at my level, which should be taken with an enormous grain of salt.

2. A relatively strong amateur prepares for a particular opponent. Even if I found the idea of preparing for an opponent to be appealing (I very much do not), I still think it would usually be a mistake for someone of my level (~ 2100 USCF) to spend much time on a finely-grained study of a particular opponent (assuming one even has access to many of the opponent's previous games in the first place), for the basic reason I spelled out above: I don't know enough to draw the right conclusions.
Despite that, I have lately found myself facing many repeat opponents because I've been playing a lot at my local club, and without having set out specifically to do so, I have ended up getting a useful sort of individualized preparation from previous games. For instance, there is a fellow expert player who I've now faced 6 times. The first two games were hard-fought draws in which I was on the defensive each time, and somewhat fortunate not to lose. The crude knowledge I obtained about him from those games, and which has proved useful, was just (1) that he is very aggressive and seemingly always looking for a direct attack, and (2) that apparently I could outplay him when things were kept quiet.
In the 4 games since, I have 3 wins and 1 loss, but that loss was only because of a fingerfehler when playing out what would've been mate-in-3 during a time scramble (probably the only time I've ever been truly angry after a game). In terms of the objective chess play, things have gone very poorly on his end since my realization about how to approach him. We have nearly identical ratings, and I believe that my recent success against him can be directly attributed to this very rudimentary sort of "preparation," namely: I know that if I play cautiously and sufficiently deaden the position against this opponent, then the resulting game suits me much more than it does him.

But that's as fine a point as someone like me can put on the matter: "I like quiet, he likes chaos." Big whoop. This is of course a far cry from the sort of preparation Fischer carried out, but that's as it should be, and even so it has proved useful for my own modest purposes. An important point here is that this information is something that I discovered naturally in the course of playing this opponent, and was not something I devoted separate time and energy to figuring out (which I maintain will often be quite a waste of time).
Finally:

3. A novice prepares for a particular opponent. This really shouldn't happen, as the novice's energies should most definitely be focused on all-around improvement, rather than on any particular traits of an opponent's play. Taking what I wrote above a step further, the novice simply isn't equipped to draw many appropriate/useful conclusions at all from an opponent's earlier games, and should instead simply direct all effort toward playing good moves and a solid game.


The following traps do not lead to any positional loss for the side setting the trap. It's obviously not an exhaustive list-

A common trap in the Sicilian

  [FEN ""]

  1. e4 c5 2. Nf3 d6 3. c3 Nf6 4. Be2 Nxe4?? 5. Qa4+ Bd7 6. Qxe4

Queen's Gambit Elephant Trap

  [FEN ""]
  1. d4. d5 2. c4 e6 3. Nc3 Nf6 4. Bg5 Nbd7 5. cxd5 exd5 6. Nxd5?? Nxd5 7. Bxd8 Bb4+ 8. Qd2 Kxd8 9. e4 Bxd2+

Trap in the Alapin Sicilian

  [FEN ""]
  1. e4 c5 2. c3 d5 3. exd5 Qxd5 4. d4 e6 5. Nf3 Nc6 6. Bd3 cxd4 7. cxd4 Nxd4?? 8. Nxd4 Qxd4?? 9. Bb5+ Bd7 10. Qxd4

Cambridge Springs Trap

  [FEN ""]
  1.d4 d5 2.c4 e6 3.Nc3 Nf6 4.Bg5 Nbd7 5.e3 c6 6.Nf3 Qa5 7. Bd3?! dxc4 8. Bxc4 Ne4 9. Qc2?? Nxg5 10. Nxg5 Qxg5

Trap in Sveshnikov Sicilian

  [FEN ""]
  1. e4 c5 2. Nf3 Nc6 3. d4 cxd4 4. Nxd4 Nf6 5. Nc3 e5 6. Ndb5 d6 7. Nd5 Nxd5 8. exd5 Ne7 9. c4 a6? 10. Qa4 axb5 11. Qxa8 (10...Qd7 11. Nxd6+)

Trap in the Philidor defense

  [FEN ""]

    1. e4 e5 2. Nf3 d6 3. d4 Nd7 4. Bc4 Be7? (4... Ngf6? 5. dxe5 Nxe5 6. Nxe5 dxe5 7.
    Bxf7+ Kxf7 8. Qxd8 Bb4+ 9. Qd2 Bxd2+ 10. Nxd2) 5. dxe5! dxe5?? (5... Nxe5 6. Nxe5
    dxe5 7. Qh5 g6 8. Qxe5) 6. Qd5 Nh6 (6...Nf6?? 7.Qxf7#) 7. Bxh6 O-O 8. Be3

Ruy Lopez Noah's Ark Trap

   [FEN ""]

    1. e4 e5 2. Nf3 Nc6 3. Bb5 a6 4. Ba4 b5 (4... d6 5. d4 b5 6. Bb3 Nxd4 7. Nxd4
    exd4 8. Qxd4?? c5) 5. Bb3 d6 6. d4 Nxd4 7. Nxd4 exd4 8. Qxd4?? c5 9. Qd5 Be6 10.
    Qc6+ Bd7 11. Qd5 c4

Siberian Trap in the Smith-Morra Gambit

    [FEN ""]

    1. e4 c5 2. d4 cxd4 3. c3 dxc3 4. Nxc3 Nc6 5. Nf3 e6 6. Bc4 Qc7 7. O-O Nf6 8.
    Qe2 Ng4 9. h3?? Nd4! 10. Nxd4 (10. hxg4 Nxe2+) (10. Qd1 Nxf3+ 11. Qxf3 Qh2#) 10...
    Qh2# 0-1

Trap in the Rauzer Sicilian

    [FEN ""]

    1. e4 c5 2. Nf3 d6 3. d4 cxd4 4. Nxd4 Nf6 5. Nc3 Nc6 6. Bg5 e6 7. Qd2 a6 8. f4
    h6 9. Bh4? Nxe4! 10. Nxe4 (10. Bxd8 Nxd2 11. Nxc6 bxc6 12. Bc7 Nxf1) 10... Qxh4+
    11. g3 Qd8


The touch-move rule never compels you to make an illegal move. It may compel you to make a stupid move, but not an illegal one. For example, you'd be forced to move a knight that's pinned against your queen and lose your queen as a result, but you'll never be compelled to move an absolutely pinned knight which would put you in check.

See this related question for more discussion, but I'll quote here the relevant FIDE rule here:

  4.5 If none of the pieces touched in accordance with Article 4.3 or
  Article 4.4 can be moved or captured, the player may make any legal
  move


After Qb3 or Qb5, black has the move Rb4 - kicking the queen away from the defense of the knight. In that line, white is losing a full piece. There is slightly more compensation by instead playing Nxb6 Rxc4 Nxc4 because at least there the black king is also exposed.
If you're ever confused on why the engine played the move it did, just turn on the analysis afterwards. Make the move that you expected the engine to play and see why that loses worse than what was actually played - that way you can learn without having to ask an online forum for help :P


How to setup a chess engine to play itself?

Yes, Arena can do what you want.

Download Arena 3.5

http://www.playwitharena.com/?Download
Adding Komodo (or any other engine) to Arena:

On the menu select Engines -> Manage
Open the Details tab
Click the new button
Point it at the executable
Select Ok
If you want it to play itself from a certain position you can set up an
engine tournament using an epd file to set the position
you want the engine to play from, and then in the settings for the tournament
if you hit the level button you can set a fixed time intveral, or fixed depth
for the engine to play. To create an epd file, you can copy the position from
Scid using Edit->Copy to FEN, and then in Arena using Position->Get FEN from
Clipboard, and then EPD->Save Position in EPD Format. This file would then
passed to the engine tournament dialog.

There might be a way to get it to play itself from a position without using
the engine tournament, but I'm not that familiar with the interface.
If you want to have it analyze a game that has already been played, or what
has been played so far can use automatic analysis under the Engines menu.

Arena seems to have a pretty thorough help file, so most of your questions will
probably have answers in there.

Edit: It was pointed out in another question that the demo button in Arena will
      have the engine play itself. So you can just set up the position, make
      sure komodo is loaded, Go into Level->Adjust to set the time interval you
      want for moves, and then hit the demo button.


I searched through all of the 1 317 676 games in The Week in Chess found two that fit the criteria.

H Dang vs D H Nguyen, 2015
P Ponkratov vs V Fedoseev, 2016


What are the possible results of a game?

In addition to the things mentioned, at least two categories are missing in my opinion. The first one is "A oversteps time when B does not have enough mating material" and the second one is "A didn't arrive at the chessboard in time and B won".

Let's structure it a bit better so we make sure we don't miss anything. I have marked some of them with an asterisk to indicate that the cases exist but may well be handled by other categories.

Game scheduled to start.
(*) Game postponed. (If we have game in progress, we should have this one as well. Otherwise, put it under 1.)
Game finished without any moves played. This is important because whether a game will be rated or not depends on whether every player has played at least one move.

a) White arrived at the chessboard after default time. (-:+, § 6.7)

b) Both players arrived at the chessboard after default time. (-:- or 0:0)
Game in progress. (As mentioned in the other answer.)
(*) Game adjourned. (Appendix E. I think there are still events in the world where this happens, but none of these are actually serious enough to warrant this category. I guess FIDE will remove it over the course of the next ten years. However, it is possible on some internet servers (e. g. FICS), so don't put it too far away if you want to cater for that as well. If not, it should be 4.)
Game finished according to the Basic Rules of Play. (The "basic rules of play" are the first five articles of the Laws of Chess; the other articles are called "Competition rules".)

a) White wins by checkmate. (1:0, § 5.1a)

b) Black resigns. (1:0, § 5.1b)

c) (*) Game drawn by stalemate. (½:½, § 5.2a) This is a special case of d), but, undoubtedly, it is a very special case and deserves its own category.

d) Game drawn by dead position. (½:½, § 5.2b)

e) Game drawn by mutual agreement. (½:½, § 5.2c)
Game finished by the clock.

a) (*) Black's flag falls during the n-th time control and the player has not completed the required number of moves. (§ 6.4 in conjunction with § 6.3a) You may merge a) and b), but then, unless you add time indicators, the two cases are indistinguishable. (1:0)

b) Black's flag falls during the last time control. (1:0)

c) (standard) Both flags have fallen and it is not clear which one fell first. (§ 6.11) (½:½, § 6.11b)

d) (*) (standard) In the last time period, both flags have fallen but Black's flag fell first. (Can be put under a) or b)) (1:0)

e) (rapid and blitz) Both flags have fallen. (½:½, Appendix A, § 4c)

f) White's flag falls, but Black has not enough mating material. Draw. Note that this is not necessarily 6d. (e. g. KB v KQ is always at least drawn for black). (You actually need this for a), b), and d) separately. See note below the list.) (0:½)
Game finished according to article nine of the laws of chess. (The drawn game.)

a) Drawn by claim of three-fold repetition by white. (½:½, § 9.2b)

b) Drawn by claim of score-sheet written intention of three-fold repetition by white. (½:½, § 9.2a)

c) (*) Drawn because X claimed draw by three-fold repetition and implicit draw offer was accepted by Y. Could be regarded as a normal draw offer. (½:½, § 9.2 in conjunction with § 9.1.b.3)

d) Drawn by claim of 50 move rule by white. (½:½, § 9.3b)

e) Drawn by claim of score-sheet written intention of 50 move rule by white.  (½:½, § 9.3a)

f) (*) Drawn because X claimed draw by 50 move rule and implicit draw offer was accepted by Y. Could be regarded as a normal draw offer. (½:½, § 9.2 in conjunction with § 9.1.b.3)

g) Drawn by article 9.6a (the same position has appeared, as in 9.2b, for at least five consecutive alternate moves by each player, new rules!) (½:½)

h) Drawn by article 9.6b (any consecutive series of 75 moves have been completed by each player without the movement of any pawn and without any capture, new rules!) (½:½)
Game results in a quickplay finish. (appendix G, only in standard and rapidplay without increment) Maybe add an indicator where the increment time mode starts if appendix G4 is applied. In those two minutes, all other things mentioned here may well happen (checkmate, illegal moves, whatever).

a) Arbiter declares game drawn immediately. (½:½)

b) Arbiter awards extra two minutes and declares game drawn afterwards. (½:½)

d) (in games without the supervision of an arbiter) An external arbiter decides according to G6.
Game finished by decision of an arbiter because of a breach of rules of one player.

a) (standard games) Game lost because of two irregular moves by Black. (1:0, § 7.5b).

b) (standard games) Like a), but White does not have enough winning material (½:0, § 7.5b).

c) (*) (old rules, standard and rapidplay) Game lost because of three irregular moves by Black. (1:0) (It is very unlikely these cases have been recorded for past tournaments.)

d) (*) (old rules, standard and rapidplay) Like c), but White does not have enough winning material. (½:0) (It is very unlikely these cases have been recorded for past tournaments.)

e) (rapidplay and blitz) An incorrect move by Black is oberserved by the arbiter or correctly claimed by White. (1:0)

f) (rapidplay and blitz) Like e), but White does not have enough winning material. (½:0)

g) (blitz) The arbiter observes both kings being in check or an unfinished pawn promotion and the position is still on the board after one move. (½:½, Appendix A, §4a.)

h) Black brings a mobile phone and/or other electronic means of communication in the playing venue (1:0, note that White wins even with insufficient material!).

i) Game finished by decision of an arbiter because of misconduct by Black. (1:0, § 12.9 decision)
Game finished by decision of an arbiter because both players persistently refuse to comply with the laws of chess. Note that both players lose in this case. (0:0, Maybe this should be 10l))
(*) Game finished because of an irregularity at the start of the game. Now, I hope a game at a level worth recording will never be replayed according to § 7.2 (wrong initial placement of pieces). Additionally, semantically, there will still only be one game, so this should not be an end-of-game marker.
(*) Result to be decided.
(*) Game abandoned.
(*) Result unknown. (e. g. notation incomplete)

Another note: maybe one should have an insufficient material marker. Then you can simplify a couple of the above cases.

In the case of a team event, for example, you need two different results to represent the game properly: For example, here in Germany, if two players sit in the wrong places, one of the games will be declared lost even after the game has finished. All the cases where this can happen are in a team context, though, so it should be possible to implement this in a different way. Recent development of electronic cheating means this is very much a possibility: the game where the player has been found to be cheating will certainly be declared lost for him. However, it might be decided that for the competition, all games will be declared lost, but they still count towards the rating (although even this is a corner case).

Yes, tournament chess can be complicated.


Why is it said that beginning with 1. Nf3 2. c4 avoids the Benoni but beginning with 1. d4 2. c4 does not?

With both move orders white can avoid the Benoni. The difference is all about which sidelines you allow and which ones you don't.

1. Nf3 c5 2. c4 is generally considered the most flexible move order for white since they can wait and play d4 at the moment of their choosing.

1. d4 Nf6 2. c4 c5 3. Nf3 cxd4 4. Nxd4 on the other hand gives black extra options, for instance the interesting gambit

    [FEN ""]
    1. d4 Nf6 2. c4 c5 3. Nf3 cxd4 4. Nxd4 e5 5. Nb5 d5 6. cxd5 Bc5

Have a look at the following game where I was the victim: Madsen-Hodgson.

Another option black has after 1. d4 Nf6 2. c4 c5 3. Nf3 cxd4 4. Nxd4 is to play like Kramnik did against Kasparov.

   [FEN ""]
   [Event "Braingames World Chess Championship"]
   [Site "London"]
   [Date "2000.10.19"]
   [Round "7"]
   [Result "1/2-1/2"]
   [White "Garry Kasparov"]
   [Black "Vladimir Kramnik"]
   [ECO "A31"]
   [WhiteElo "2849"]
   [BlackElo "2770"]
   [PlyCount "21"]

   1. c4 c5 2. Nf3 Nf6 3. d4 cxd4 4. Nxd4 a6 5. Nc3 e6 6. g3 Qc7
   7. Qd3 (7.Bg2) Nc6 8. Nxc6 dxc6 9. Bg2 e5 10. O-O Be6 11. Na4 1/2-1/2

To get an advantage in this variation, white might have to sacrifice the c4 pawn instead of covering it with 7. Qd3.

A third option black has is to enter the Hedgehog with

    [FEN ""]
    1. d4 Nf6 2. c4 c5 3. Nf3 cxd4 4. Nxd4 b6 (4... b6 5.g3?)

In this move order white should not fianchetto the bishop with 5.g3 since black's bishop is first on the long diagonal.


If your GUI allows custom UCI options (I think you can do it in Arena, but check its documentation), you should be able to add a syzygy path yourself. Otherwise, you may try the popular Deep Fritz GUI. Check this link:

http://talkchess.com/forum/viewtopic.php?t=50554&highlight=syzygy+deep+fritz


You do not have enough control of e4, and if white gets to play e4-e5 here, your king is a goner. It is an absolute must here to stop that plan, and the only way to do it is d5. Making your Bb7 bad for now pales in comparison to letting your king get mated, or loss of significant material, which will happen after e4-e5.


Why couldn't I win this Maroczy Bind (vs 2000)?

You couldn't win mostly due to the mistake on move 19, but you still had chances.

  I played 11.f4 with the intention of maintaining control over e5 and keeping open the option of eventually breaking with e4-e5 or
  f4-f5:

That statement is not enough of a plan, and your following moves don't support either idea.  That pawn cannot move backwards and you might wish it were on f3.

  12.Bf3, perhaps 12.h3

Again you are not playing with any plan, but Bf3 supports e4 and is probably a better square for the Bishop

  I felt happy with 14.h3

Why? How does 14.h3 help your position?  I can't help thinking there is something wrong with your position.  Your rooks aren't connected and the long dark-square diagonal is loose, but I don't know that Black can take advantage of that.

  error with 15...e5.

Yes that is dubious, and I think Black could have improved his rooks before trading knights in the center.

  17.Qxd6 looked safe, but perhaps I was better off with 18.Qxf4 or 19.Qxf4 rather than 19.Bxf4?!, allowing 19...Qb6+.

or 19.Qd8, which looks to give you a big advantage!  19...Rfxd8 20.Bxf4 Rd4?! 21.Ne2 +/-

  After 22.Nd5 I really don't understand where I could've improved

Well, what did 26.Bg4 achieve but to weaken your e-pawn?  How about, 26.Rcd1 Bxc5 27.Bc7 Ra4 28.Bg4

  33.Rb1

Why help Blacks rook get in the game?  Also, every pawn trade makes it harder to win the game.


How to package PGN in Lichess analysis page format

My guess is that just saving the HTML, Javascript, etc. didn't work because the Lichess site also has a server component. If you want to go down that road (which seems like a lot of work!), Lichess is open source; see https://github.com/ornicar/lila .

But maybe you could let lichess.org do the hard work and embed the Lichess view of the games in your website. That is supported: see "Embed a chess analysis in your site" and "Embed a chess game in your site" at https://lichess.org/developers . Unfortunately, I don't think it supports Stockfish and analysis within the embedded widget itself, but it does have a link to go to the full version on lichess.org.


Can luck be used as a strategy in chess?

Whether or not to resign is a question of sportsmanship rather than strategy, I would argue. Just according to the rules, you are never forced to resign and can play on until you are checkmated. However, it is expected (to a certain degree) that you resign in a position that is "clearly" lost.
There is no definite definition when a position is "clearly" lost though. If I am down a rook against Magnus Carlsen, I would definitely resign, because the chances of Carlsen blundering and giving me an opportunity to turn the game are infinitesimally small. Similarly, if Carlsen were able to gain a pawn without me gaining any compensation for it, I might resign as well (especially if it were the endgame). Again, Carlsen is expected to turn this advantage into a win eventually, and hoping that he will make an unrealistic mistake would be poor sportsmanship. On the other hand, if I was playing an opponent of my strength level, then a single pawn advantage might not be enough for him to find the win (even though the game might be already lost at perfect play). Instead, I would continue playing against my opponent until he demonstrated that he is aware of how to utilize the advantage to create a win (e.g., by creating a passed pawn that I can only stop by sacrificing another piece).


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

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

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


How to generate hash keys for chess positions

I believe you're talking about Zobrist Hashing.

  a technique to transform a board position of arbitrary size into a number of a set length, with an equal distribution over all possible numbers

https://chessprogramming.wikispaces.com/Zobrist+Hashing

Why Zobrist?

Rather than computing the hash for the entire board every time, the hash value of a board can be updated simply by XORing out the bitstring(s) for positions that have changed. That makes the hashing algorithm very efficient for chess engines.


Does anything actually use numeric annotation glyphs (NAGs)?

Yes, ChessBase does more than just support them, it definitely uses them.

Since I got here, due to how I write notation, de instead of dxe4, for example, I used to have problems getting the FEN board here to work. Now, I have figured it out, but I still input my answer into a ChessBase board first, including annotations, and then Home>Copy Game, paste it here, edit the header information as needed, format the header as needed by this site, and remove a few extraneous spaces that the copy process adds.

There is no symbol for "$115 means "black has played the middlegame very poorly" in ChessBase, but those other common symbols are definitely in my pasted PGN.

I created this totally bogus game, but it shows what it looks like when properly formatted, and then the original PGN with NAGs. This was copied from ChessBase, and I just needed to remove spaces that appear when pasting. It is interesting that the last one, $143 did not work as did not the ones at move 4...f5 and 5. Nxf5. Maybe this PGN reader on SEC does not support all of them.

 [FEN ""]

 1. e4 $1 $14 e5 $4 2. d4 $13 exd4 $22 3. Nf3 $8 Nc6 $3 4. Nxd4 $40 f5 $44 5. Nxf5 $138 d5 $32 6. exd5 $146 Ne5 $132 7. Bb5+ $140 (7. Be2 $142) (7. Bc4 $143)

e4 $1 $14 e5 $4 2. d4 $13 exd4 $22 3. Nf3 $8 Nc6 $3 4. Nxd4 $40 f5 $44 5.
Nxf5 $138 d5 $32 6. exd5 $146 Ne5 $132 7. Bb5+ $140 (7. Be2 $142) (7. Bc4 $143)


What happens if a player dies at the board? What is the ruling?

Clock runs out and they lose on time if it is the   move of the dead player.
Otherwise the opponent could resign or move;  unless a draw was offered before the death in which case they could accept the draw (why?) , resign (but more why?), or move and wait for the clock to run out on the now dead opponent.


What is the maximum number of squares 8 queens and 8 nightriders can attack on a 16x16 board?

It's possible to attack all squares.

Q - queen

N - nightrider

Yellow background - attacked only by a queen

Red background - attacked only by a nightrider

Orange background - attacked by pieces of both types

Queens are placed such that 5 longest diagonals in each direction are attacked.

This can be done with just 6 queens, so 2 are redundant and result in queens attacking queens by diagonals. So 4 queens are attacked by other queens, 4 are not. I added nightriders on the edge of the board such that the missing squares are also attacked. Placing nightriders on the edge doesn't block any of the queens' attacks.

One can also see that the nightriders attacking queens could be placed in other ways, so there is more than one solution. An interesting question would be-how many?

edit. now correct...


White can't defend the a3-pawn. The White king is defenceless on the queenside, and you have the knight on a great outpost near the White king, the bishop a mere ...d5-d4 away from joining the attack. The Black queen is entering the fray either via Qb6 or Qa5. both Black rooks can participate in the attack through Rc6-b6 or Rc6-a6, or along the c-file.
Basically a chess engine can't find a way to defend against the oncoming attack along the a- and b-files aimed at the White king.
Black's immediate threat is to play ...Nxa3 threatening ...Rxc2+. White defends that by playing c2-c3. White's best option at this point is to evacuate the king over to the kingside, so White's best moves of Rd1-f1 are there to clear space for the White king to walk from c1-d1-e1-f2. While he's doing that, Black is bringing his pieces quickly into White's half of the queenside attacking the king directly.


Yes, he played a game against Alick Glennie, actually he created an algorithm based on mathematical calculations. Then he tried his algorithm using pen and paper to do calculations.

[fen ""]
[White "Alan Turing"]
[Black "Alick Glennie"]

1.e4 e5 2.Nc3 Nf6 3.d4 Bb4 4.Nf3 d6 5.Bd2 Nc6 6.d5 Nd4 7.h4 Bg4 8.a4
Nxf3+ 9.gxf3 Bh5 10.Bb5+ c6 11.dxc6 O-O 12.cxb7 Rb8 13.Ba6 Qa5
14.Qe2 Nd7 15.Rg1 Nc5 16.Rg5 Bg6 17.Bb5 Nxb7 18.O-O-O Nc5
19.Bc6 Rfc8 20.Bd5 Bxc3 21.Bxc3 Qxa4 22.Kd2 Ne6 23.Rg4 Nd4
24.Qd3 Nb5 25.Bb3 Qa6 26.Bc4 Bh5 27.Rg3 Qa4 28.Bxb5 Qxb5
29.Qxd6 Rd8 0-1

The main idea of algorithm is here:

Mobility: For the queen, rooks, bishops, add the square roots of the number of moves that the piece can make, counting a capture as two moves.
Piece safety: For the rooks, bishops and knights add 1 point if there is one defender and 1.5 if there is more than one
King mobility: For the king use the same method of scoring as for the piece, but do not count castling
King safety: Deduct points for the king's vulnerability, defined as the number of moves that a queen could make were it on the square of the king
Castling: add 1 point if castling is still legally possible after this move. Add another point if castling is immediately possible or if a castling move has just been made
Pawn credit: score .2 points for each rank advanced and .3 points for each pawn defended by one or more non pawns
Check and mate threats. Score 1 point for the threat of mate, and .5 points for a checkmaterial values used to each of the pieces were:pawn =1, knight=3, bishop=3.5 rook =5, queen=10


In a online game, is it considered good etiquette to offer a draw when the opponent obviously misclicked?

Just to offer a different answer:

No. No takebacks, no draw offers. In short time controls this is part of the game. It's the same as a blunder under pressure. I pressured the opponent on either time or position, and the person cracked and made a mistake.

Or your other example, of moving the king instead of castling in the beginning: That's what one get for trying to blitz out moves. Might save you a second here and there, but the risk is these mis-clicks. That's a price my opponent will have to pay, can't have the cake and eat it too.

(For longer time controls (1h+) I might think trying to salvage the game is the right choice, but I only really play 5min and below)


What are some good books on the Italian game, including the Evans Gambit and Two Knights Defense family of openings?

When I looked for a similar book, the best I could find is this somewhat dated work by Jan Pinski.

This newer book by Glenn Flear apparently contains 88 pages about the italian, Evan's gambit and two knights.

If you have played the Bishop's opening before maybe this is the book for you: It advocates going into the Italian game by 2.Bc4.


Who better to answer this question than the legendary former World Champion and master of opening preparation Garry Kasparov himself? I quote

  In June 2005 in New York I gave a special training session to a group
  of the leading young players in the United States. I had asked them
  each to bring two of their games for us to review, one win and one
  loss. A talented twelve-year-old raced through the opening moves of
  his loss, eager to get to the point where he thought he'd gone wrong.
  I stopped him and asked why he had played a certain pawn push in the
  sharp opening variation. His answer didn't surprise me: "That's what
  Vallejo played!" Of course I also knew that the Spanish Grandmaster
  had employed this move in a recent game, but I also knew that if this
  youngster didn't understand the motive behind the move, he was already
  headed for trouble.

  This boy's response took me back to my own sessions with Botvinnik
  thirty years earlier. On more than one occasion he chided me for
  committing this same sin of blind emulation. The great teacher
  insisted that his students recognize the rationale behind every move.
  As a result, all of us learned to become great skeptics, even of the
  moves of the best players. We would discover a powerful idea behind
  each Grandmaster move, but we also found improvements. We studied, we
  questioned, we grappled with the idea behind a series of moves, and
  eventually we could build our understanding and create more and better
  strategies.

  For players who depend on memorization, the opening ends when their
  memory runs out of moves and they have to start thinking for
  themselves. A rote opening might carry you to move five, or even move
  thirty, but this practice always inhibits your development as a
  player. It is one thing for a world-class player to rely on
  memorization; he already knows all of the whys behind the moves. For
  your own development it's far more important to think for yourself
  from the very start.

  --- Garry Kasparov, How Life Imitates Chess (emphasis mine)

Following Garry Kasparov's advice, I myself do not recommend memorization of opening moves. If you really want to improve your game, you must understand (rather than memorize) why a certain move is played and only then play it.

  Should I do memorizing to saved time in middle game?

No! Instead, you should study the openings more and understand why certain moves are played. When you understand these moves, the result is that you often automatically remember them because you have found the rationale behind them. The focus should be on understanding and not on memorization.

Great players have fallen prey to blind memorization, including legends like Viswanathan Anand himself. Consider the game where he lost in just 6 moves (!!!) because he blindly memorized a line played earlier by a grandmaster.

     [FEN "rnbqkbnr/pppppppp/8/8/8/8/PPPPPPPP/RNBQKBNR w KQkq - 0 1"]
     [Event "Blind memorization makes Anand lose in 6 moves"]
     [White "Zapata"]
     [Black "Anand"]

     1. e4 e5 2. Nf3 Nf6 3. Nxe5 d6 4. Nf3 Nxe4 5. Nc3 Bf5?? 6. Qe2! 1-0

Or consider his loss in the first game in his World Championship match with Topalov where he "forgot" his preparation and blundered and lost the game.

     [FEN "rnbqkbnr/pppppppp/8/8/8/8/PPPPPPPP/RNBQKBNR w KQkq - 0 1"]
     [Event "Anand forgets his preparation and blunders"]
     [White "Topalov"]
     [Black "Anand"]
     [Result "1-0"]

     1. d4 Nf6 2. c4 g6 3. Nc3 d5 4. cxd5 Nxd5 5. e4 Nxc3 6. bxc3 Bg7 7. Bc4 c5 8.
     Ne2 Nc6 9. Be3 O-O 10. O-O Na5 11. Bd3 b6 12. Qd2 e5 13. Bh6 cxd4 14. Bxg7 Kxg7
     15. cxd4 exd4 16. Rac1 Qd6 17. f4 f6 18. f5 Qe5 19. Nf4 g5 20. Nh5+ Kg8 21. h4
     h6 22. hxg5 hxg5 23. Rf3 Kf7?? ({not thinking objectively and trying to repeat moves from memory}) 24. Nxf6 Kxf6 25. Rh3 Rg8 26. Rh6+ Kf7 27. Rh7+
     Ke8 28. Rcc7 Kd8 29. Bb5 Qxe4 30. Rxc8+ 1-0

Now to redeem Anand a bit, I must mention his smashing win against Bologan, where Bologan blindly copied a line that had been played by other grandmasters before and got smashed by Anand's stunning novelty.

    [FEN ""]
    [Event "Bologan merely copies known opening moves and Anand punishes him"]
    [White "Anand"]
    [Black "Bologan"]
    [Result "1-0"]

    1. e4 c6 2. d4 d5 3. Nc3 dxe4 4. Nxe4 Nd7 5. Ng5 Ngf6 6. Bd3 e6 7. N1f3 Bd6 8.
    Qe2 h6 9. Ne4 Nxe4 10. Qxe4 Qc7 11. O-O b6 12. Qg4 g5 13. Qh3 Rg8 14. Re1!! Bf8
    15. Qf5 Bg7 16. h4 Kf8 17. Qh3 Rh8 18. hxg5 hxg5 19. Qg4 c5 20. Bxg5 cxd4 21.
    Rad1 Bb7 22. Rxe6 fxe6 23. Be7+ Kxe7 24. Qxg7+ Kd6 25. Nxd4 Qc5 26. Bf5 Qe5 27.
    Nf3+ Qd5 28. Qg3+ Ke7 29. Rxd5 Bxd5 30. Qg5+ Kd6 31. Qf4+ Ke7 32. Be4 Rh5 33.
    Nh4 Rg8 34. Ng6+ Kd8 35. Qf7 Re8 36. Bd3 1-0

Even after this game, I checked a database and found that many strong players unaware of this novelty also lost their games in this variation in the same manner.

Moral of the story - do not merely copy the moves of grandmasters or just memorize them. Analyze them and understand them and see if they can be improved.


The Steps Method is a graduated series of books that attempts to provide all material necessary to take a player from complete beginner to expert. I have not used it but it has a strong reputation.

To proceed past that, the best thing I can think of is Yusupov's 9-book course (Build Up Your Chess et al), which is around 2700 pages in total and attempts to take a player from about 1500 FIDE to master. I am a bit more than halfway through and give it a great deal of credit for my rise from 1800 to 2000 USCF.

Of course, either (or both) of these series must be supplemented by actually playing games.


Make chess engine play a particular position

In Scid vs PC got to Edit > Setup Board. Here you can setup the board with a particular position, set side to move and castling flags. Easier is if you have a FEN of the position, you could just paste this and use it directly. Click OK once you are done to get the position on the main board.

Now navigate to Play > Computer-UciEngine > Choose your stockfish engine, Check "Start from current position", Set desired time control and click "Play".


b3 Nh5 following
fxe4 leading to losing your knight (did not see the discovered attack)
Qxh5

To save the knight you would have needed to play pawn g6 on 13. instead of playing dxe4

Playing back to Nf6 will get you forked with white moving pawn to e5 on move 14.

It is all down the hill from then on.

Also on 31.

Moving the King out into the wild is also problematic as you saw with the pinned bishop and the checkmate with the rook!


How can you castle legally in Chess960 when the castling rook is on the king's destination square?

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

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

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

The FIDE Laws of Chess go on to state:

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

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

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

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


Is the notion of an en passant redundant?

If nothing else, it does help to make similar looking pawn structures, behave similarly independent on which row they occur.

For instance with en-passant: white: pawn h5, black pawns on h6, g7 would be somewhat equal to the position where white: pawn on h4, black pawns on h5, g6.

Without en-passant however black would be able to achieve a protected passed pawn (often a huge advantage in many endgames) in the first situation by simply playing g7-g5 without being in danger of being captured.

Thus not having en-passant would change the evaluation of many endgames and complicate rules somewhat because now you'd have to consider on what row the pawns are as well.


Adding on to Brian Towers' answer, there is a quick way you can script this (assuming you are on Linux or another POSIX system with the tr command):

cat gamelog.txt | tr 'abcdefgh12345678' 'hgfedcba87654321' > gamelog_reversed.txt

Edit: as @wimi said, this will mess up move numbers, so be careful about that. You may want to use cut and paste to seperate only the columns with the moves.


Id' reckon converting an advantage into an actual win has a lot to do with keeping in mind that a position is worth nothing unless you are there to steer it accurately towards victory. Otherwise it's very easy to be visited by 'the ghost of the won position', which would try to convince you that you can relax before the game is over, trying to trick you into making unneccessary mistakes which would diminish your advantage.

When you write "finish" I interpret that as "converting a big advantage into a win". Is this a correct interpretation? If so, then it all depends on the position at hand; if your opponent played an unsound sacrifice for an attack you may have to defend, while if your opponent played too passively you may have to attack to accurately steer the game towards its logical conclusion.


Can Black always choose seating position and clock position?

It is an interesting question, but you already gave the answer. It is the arbiters decision where the players sit and the clocks are placed (so that the arbiter can see them best). When no official arbiter is present, the team captain of the home team acts as arbiter. These rules are for tournaments and club matches. Casual is of course different.
If a player does not follow the arbiters decision he can get penalized (eg. time reduction, which happened few months ago at our club match, because of the exact same clock positioning question)


Why isn't 6.Bc4 considered by theory in the 5.Bxf7+ Traxler Counterattack?

Comparing 6.Bb3 and 6.Bc4, the drawbacks of the latter are obvious since the bishop is not protected and can become a target to attacks:

either by a black piece: Ne5, Na5, Qc5, Qd4...

or, more probably, by the d-pawn: the typical ...d5 will gain a tempo for development

On the other hand, I can see no advantage of having the bishop on c4 rather than b3. You will hardly ever want to retreat to e2, nor to play a queenside fianchetto.
Given how important each tempo can be in such an complicated line, it is understandable than no strong player has ever ventured 6.Bc4. Probably there isn't a direct refutation, but you might regret having your bishop exposed later on.


In a general way chess engines use a decision tree. The root of the tree is the current position and has a child node for each position that can be made by making a legal move. Each of these nodes in turn have a child node for the positions that can be reached by making a legal move from them. The engine pushes the tree out to a depth defined by its capabilities and the time it is allowed to "think". Positions that can be reached in more than one way are simply cross referenced so that they will not have to be considered more than once. Once the tree is created the computer uses a set of weighted rules to analyze the final positions in the tree and starts to remove those that are undesirable or that the opponent can prevent it from reaching. The tree is cut down this way until only one move remains and the computer makes that move.

http://www.chess.com/blog/zaifrun has series or articles on creating a chess engine if you want a more in depth look at how they work.


FIDE rules regarding use of foreign languages in algebraic notation

As a native Russian player I may assure you that we always used the suggested notation, e.g. Фd4 or Лd1 (Ф - ферзь - for Queen, Л - ладья - for Rook, etc); even the 6 years old beginners did so. Nobody ever was insane enough to suggest Russian alphabet for encoding files.


Longest Sequence For Any Piece To Reach A Certain Square

Thanks for the fun question, and welcome to CSE! For this kind of construction problem, the king is obviously the piece to choose.
Addendum 10/12/2020: The position that used to be here proved defective, so here is a new position, Unfortunately over a hundred moves had to be cut. Here is my new offering of 336 moves, with the White king going to b7,
[Title "me, chess.stackexchange.com 10/12/2020, White forces Black to let their king move to b7 in  336 moves"]
[FEN "Kb1n1b1k/b1p1pBp1/1pPpPpPp/pPpppppp/ppp1p1p1/8/8/pppppppp w - - 0 1"]

1. Be8 Kg8 2. Bd7 Kh8 3. Bc8 Kg8 4. Ba6 Kh8 5. Bb7 Kg8 6. Bc8 Kh8 7. Bd7 Kg8 8. Be8 Kh8 9. Bf7 a3 10. Be8 Kg8 11. Bd7 Kh8 12. Bc8 Kg8 13. Ba6 Kh8 14. Bb7 Kg8 15. Bc8 Kh8 16. Bd7 Kg8 17. Be8 Kh8 18. Bf7 a2 19. Be8 Kg8 20. Bd7 Kh8 21. Bc8 Kg8 22. Ba6 Kh8 23. Bb7 Kg8 24. Bc8 Kh8 25. Bd7 Kg8 26. Be8 Kh8 27. Bf7 a4 28. Be8 Kg8 29. Bd7 Kh8 30. Bc8 Kg8 31. Ba6 Kh8 32. Bb7 Kg8 33. Bc8 Kh8 34. Bd7 Kg8 35. Be8 Kh8 36. Bf7 a3 37. Be8 Kg8 38. Bd7 Kh8 39. Bc8 Kg8 40. Ba6 Kh8 41. Bb7 Kg8 42. Bc8 Kh8 43. Bd7 Kg8 44. Be8 Kh8 45. Bf7 b3 46. Be8 Kg8 47. Bd7 Kh8 48. Bc8 Kg8 49. Ba6 Kh8 50. Bb7 Kg8 51. Bc8 Kh8 52. Bd7 Kg8 53. Be8 Kh8 54. Bf7 b2 55. Be8 Kg8 56. Bd7 Kh8 57. Bc8 Kg8 58. Ba6 Kh8 59. Bb7 Kg8 60. Bc8 Kh8 61. Bd7 Kg8 62. Be8 Kh8 63. Bf7 c3 64. Be8 Kg8 65. Bd7 Kh8 66. Bc8 Kg8 67. Ba6 Kh8 68. Bb7 Kg8 69. Bc8 Kh8 70. Bd7 Kg8 71. Be8 Kh8 72. Bf7 c2 73. Be8 Kg8 74. Bd7 Kh8 75. Bc8 Kg8 76. Ba6 Kh8 77. Bb7 Kg8 78. Bc8 Kh8 79. Bd7 Kg8 80. Be8 Kh8 81. Bf7 c4 82. Be8 Kg8 83. Bd7 Kh8 84. Bc8 Kg8 85. Ba6 Kh8 86. Bb7 Kg8 87. Bc8 Kh8 88. Bd7 Kg8 89. Be8 Kh8 90. Bf7 c3 91. Be8 Kg8 92. Bd7 Kh8 93. Bc8 Kg8 94. Ba6 Kh8 95. Bb7 Kg8 96. Bc8 Kh8 97. Bd7 Kg8 98. Be8 Kh8 99. Bf7 d4 100. Be8 Kg8 101. Bd7 Kh8 102. Bc8 Kg8 103. Ba6 Kh8 104. Bb7 Kg8 105. Bc8 Kh8 106. Bd7 Kg8 107. Be8 Kh8 108. Bf7 d3 109. Be8 Kg8 110. Bd7 Kh8 111. Bc8 Kg8 112. Ba6 Kh8 113. Bb7 Kg8 114. Bc8 Kh8 115. Bd7 Kg8 116. Be8 Kh8 117. Bf7 d2 118. Be8 Kg8 119. Bd7 Kh8 120. Bc8 Kg8 121. Ba6 Kh8 122. Bb7 Kg8 123. Bc8 Kh8 124. Bd7 Kg8 125. Be8 Kh8 126. Bf7 d5 127. Be8 Kg8 128. Bd7 Kh8 129. Bc8 Kg8 130. Ba6 Kh8 131. Bb7 Kg8 132. Bc8 Kh8 133. Bd7 Kg8 134. Be8 Kh8 135. Bf7 d4 136. Be8 Kg8 137. Bd7 Kh8 138. Bc8 Kg8 139. Ba6 Kh8 140. Bb7 Kg8 141. Bc8 Kh8 142. Bd7 Kg8 143. Be8 Kh8 144. Bf7 d3 145. Be8 Kg8 146. Bd7 Kh8 147. Bc8 Kg8 148. Ba6 Kh8 149. Bb7 Kg8 150. Bc8 Kh8 151. Bd7 Kg8 152. Be8 Kh8 153. Bf7 e3 154. Be8 Kg8 155. Bd7 Kh8 156. Bc8 Kg8 157. Ba6 Kh8 158. Bb7 Kg8 159. Bc8 Kh8 160. Bd7 Kg8 161. Be8 Kh8 162. Bf7 e2 163. Be8 Kg8 164. Bd7 Kh8 165. Bc8 Kg8 166. Ba6 Kh8 167. Bb7 Kg8 168. Bc8 Kh8 169. Bd7 Kg8 170. Be8 Kh8 171. Bf7 e4 172. Be8 Kg8 173. Bd7 Kh8 174. Bc8 Kg8 175. Ba6 Kh8 176. Bb7 Kg8 177. Bc8 Kh8 178. Bd7 Kg8 179. Be8 Kh8 180. Bf7 e3 181. Be8 Kg8 182. Bd7 Kh8 183. Bc8 Kg8 184. Ba6 Kh8 185. Bb7 Kg8 186. Bc8 Kh8 187. Bd7 Kg8 188. Be8 Kh8 189. Bf7 f4 190. Be8 Kg8 191. Bd7 Kh8 192. Bc8 Kg8 193. Ba6 Kh8 194. Bb7 Kg8 195. Bc8 Kh8 196. Bd7 Kg8 197. Be8 Kh8 198. Bf7 f3 199. Be8 Kg8 200. Bd7 Kh8 201. Bc8 Kg8 202. Ba6 Kh8 203. Bb7 Kg8 204. Bc8 Kh8 205. Bd7 Kg8 206. Be8 Kh8 207. Bf7 f2 208. Be8 Kg8 209. Bd7 Kh8 210. Be8 Kg8 211. Bd7 Kh8 212. Bc8 Kg8 213. Ba6 Kh8 214. Bb7 Kg8 215. Bc8 Kh8 216. Bd7 Kg8 217. Be8 Kh8 218. Bf7 f5 219. Be8 Kg8 220. Bd7 Kh8 221. Bc8 Kg8 222. Ba6 Kh8 223. Bb7 Kg8 224. Bc8 Kh8 225. Bd7 Kg8 226. Be8 Kh8 227. Bf7 f4 228. Be8 Kg8 229. Bd7 Kh8 230. Bc8 Kg8 231. Ba6 Kh8 232. Bb7 Kg8 233. Bc8 Kh8 234. Bd7 Kg8 235. Be8 Kh8 236. Bf7 f3 237. Be8 Kg8 238. Bd7 Kh8 239. Bc8 Kg8 240. Ba6 Kh8 241. Bb7 Kg8 242. Bc8 Kh8 243. Bd7 Kg8 244. Be8 Kh8 245. Bf7 g3 246. Be8 Kg8 247. Bd7 Kh8 248. Bc8 Kg8 249. Ba6 Kh8 250. Bb7 Kg8 251. Bc8 Kh8 252. Bd7 Kg8 253. Be8 Kh8 254. Bf7 g2 255. Be8 Kg8 256. Bd7 Kh8 257. Bc8 Kg8 258. Ba6 Kh8 259. Bb7 Kg8 260. Bc8 Kh8 261. Bd7 Kg8 262. Be8 Kh8 263. Bf7 g4 264. Be8 Kg8 265. Bd7 Kh8 266. Bc8 Kg8 267. Ba6 Kh8 268. Bb7 Kg8 269. Bc8 Kh8 270. Bd7 Kg8 271. Be8 Kh8 272. Bf7 g3 273. Be8 Kg8 274. Bd7 Kh8 275. Bc8 Kg8 276. Ba6 Kh8 277. Bb7 Kg8 278. Bc8 Kh8 279. Bd7 Kg8 280. Be8 Kh8 281. Bf7 h4 282. Be8 Kg8 283. Bd7 Kh8 284. Bc8 Kg8 285. Ba6 Kh8 286. Bb7 Kg8 287. Bc8 Kh8 288. Bd7 Kg8 289. Be8 Kh8 290. Bf7 h3 291. Be8 Kg8 292. Bd7 Kh8 293. Bc8 Kg8 294. Ba6 Kh8 295. Bb7 Kg8 296. Bc8 Kh8 297. Bd7 Kg8 298. Be8 Kh8 299. Bf7 h2 300. Be8 Kg8 301. Bd7 Kh8 302. Bc8 Kg8 303. Ba6 Kh8 304. Bb7 Kg8 305. Bc8 Kh8 306. Bd7 Kg8 307. Be8 Kh8 308. Bf7 h5 309. Be8 Kg8 310. Bd7 Kh8 311. Bc8 Kg8 312. Ba6 Kh8 313. Bb7 Kg8 314. Bc8 Kh8 315. Bd7 Kg8 316. Be8 Kh8 317. Bf7 h4 318. Be8 Kg8 319. Bd7 Kh8 320. Bc8 Kg8 321. Ba6 Kh8 322. Bb7 Kg8 323. Bc8 Kh8 324. Bd7 Kg8 325. Be8 Kh8 326. Bf7 h3 327. Be8 Kg8 328. Bd7 Kh8 329. Bc8 Kg8 330. Ba6 Kh8 331. Bb7 Kg8 332. Bc8 Kh8 333. Bd7 Kg8 334. Be8 Kh8 335. Bf7 Nxc6 336. Kb7

As for a legal position, 111 moves is the longest I have come up with so far. White wants to move their king to any square as soon as possible.
[Title "me, chess.stackexchange.com 30/12/2019, White forces Black to allow a White king move in 111 moves"]
[FEN "5b1k/2p1pBp1/1pPpPpPp/1P1p4/8/7b/5n1P/3n2K1 w - - 0 1"]

1. Be8 Kg8 2. Bd7 Kh8 3. Bc8 Kg8 4. Ba6 Kh8 5. Bb7 Kg8 6. Bc8 Kh8 7. Bd7 Kg8 8. Be8 Kh8 9. Bf7 d4 10. Be8 Kg8 11. Bd7 Kh8 12. Bc8 Kg8 13. Ba6 Kh8 14. Bb7 Kg8 15. Bc8 Kh8 16. Bd7 Kg8 17. Be8 Kh8 18. Bf7 d3 19. Be8 Kg8 20. Bd7 Kh8 21. Bc8 Kg8 22. Ba6 Kh8 23. Bb7 Kg8 24. Bc8 Kh8 25. Bd7 Kg8 26. Be8 Kh8 27. Bf7 d2 28. Be8 Kg8 29. Bd7 Kh8 30. Bc8 Kg8 31. Ba6 Kh8 32. Bb7 Kg8 33. Bc8 Kh8 34. Bd7 Kg8 35. Be8 Kh8 36. Bf7 d5 37. Be8 Kg8 38. Bd7 Kh8 39. Bc8 Kg8 40. Ba6 Kh8 41. Bb7 Kg8 42. Bc8 Kh8 43. Bd7 Kg8 44. Be8 Kh8 45. Bf7 d4 46. Be8 Kg8 47. Bd7 Kh8 48. Bc8 Kg8 49. Ba6 Kh8 50. Bb7 Kg8 51. Bc8 Kh8 52. Bd7 Kg8 53. Be8 Kh8 54. Bf7 d3 55. Be8 Kg8 56. Bd7 Kh8 57. Bc8 Kg8 58. Ba6 Kh8 59. Bb7 Kg8 60. Bc8 Kh8 61. Bd7 Kg8 62. Be8 Kh8 63. Bf7 f5 64. Be8 Kg8 65. Bd7 Kh8 66. Bc8 Kg8 67. Ba6 Kh8 68. Bb7 Kg8 69. Bc8 Kh8 70. Bd7 Kg8 71. Be8 Kh8 72. Bf7 f4 73. Be8 Kg8 74. Bd7 Kh8 75. Bc8 Kg8 76. Ba6 Kh877. Bb7 Kg8 78. Bc8 Kh8 79. Bd7 Kg8 80. Be8 Kh8 81. Bf7 f3 82. Be8 Kg8 83. Bd7 Kh8 84. Bc8 Kg8 85. Ba6 Kh8 86. Bb7 Kg8 87. Bc8 Kh8 88. Bd7 Kg8 89. Be8 Kh8 90. Bf7 h5 91. Be8 Kg8 92. Bd7 Kh8 93. Bc8 Kg8 94. Ba6 Kh8 95. Bb7 Kg8 96. Bc8 Kh8 97. Bd7 Kg8 98. Be8 Kh8 99. Bf7 h4 100. Be8 Kg8 101. Bd7 Kh8 102. Bc8 Kg8 103. Ba6 Kh8 104. Bb7 Kg8 105. Bc8 Kh8 106. Bd7 Kg8 107. Be8 Kh8 108. Bf7 Bg2 109. h3 Ng4 110. hxg4 h3 111. Kh2

Addendum 12/23/2020: It turns out that for legal positions, longer lengths can actually be achieved by instead using a pawn as the designated piece. Here is my the new record of 124 moves.
[Title "me, chess.stackexchange.com 12/30/2019, White forces Black to allow their h7 pawn to move in 123 moves"]
[FEN "7k/p1pN2pP/2p3p1/8/p5p1/P1p2PP1/2P2P1b/5K1N w - - 0 1"]

1. Nf8 gxf3 2. Ke1 Bg1 3. Kd1 Bh2 4. Kc1 Bg1 5. Kb1 Bh2 6. Ka2 Bg1 7. Ka1 Bh2 8. Kb1 Bg1 9. Kc1 Bh2 10. Kd1 Bg1 11. Ke1 Bh2 12. Kf1 a6 13. Ke1 Bg1 14. Kd1 Bh2 15. Kc1 Bg1 16. Kb1 Bh2 17. Ka2 Bg1 18. Ka1 Bh2 19. Kb1 Bg1 20. Kc1 Bh2 21. Kd1 Bg1 22. Ke1 Bh2 23. Kf1 a5 24. Ke1 Bg1 25. Kd1 Bh2 26. Kc1 Bg1 27. Kb1 Bh2 28. Ka2 Bg1 29. Ka1 Bh2 30. Kb1 Bg1 31. Kc1 Bh2 32. Kd1 Bg1 33. Ke1 Bh2 34. Kf1 c5 35. Ke1 Bg1 36. Kd1 Bh2 37. Kc1 Bg1 38. Kb1 Bh2 39. Ka2 Bg1 40. Ka1 Bh2 41. Kb1 Bg1 42. Kc1 Bh2 43. Kd1 Bg1 44. Ke1 Bh2 45. Kf1 c4 46. Ke1 Bg1 47. Kd1 Bh2 48. Kc1 Bg1 49. Kb1 Bh2 50. Ka2 Bg1 51. Ka1 Bh2 52. Kb1 Bg1 53. Kc1 Bh2 54. Kd1 Bg1 55. Ke1 Bh2 56. Kf1 c6 57. Ke1 Bg1 58. Kd1 Bh2 59. Kc1 Bg1 60. Kb1 Bh2 61. Ka2 Bg1 62. Ka1 Bh2 63. Kb1 Bg1 64. Kc1 Bh2 65. Kd1 Bg1 66. Ke1 Bh2 67. Kf1 c5 68. Ke1 Bg1 69. Kd1 Bh2 70. Kc1 Bg1 71. Kb1 Bh2 72. Ka2 Bg1 73. Ka1 Bh2 74. Kb1 Bg1 75. Kc1 Bh2 76. Kd1 Bg1 77. Ke1 Bh2 78. Kf1 g5 79. Ke1 Bg1 80. Kd1 Bh2 81. Kc1 Bg1 82. Kb1 Bh2 83. Ka2 Bg1 84. Ka1 Bh2 85. Kb1 Bg1 86. Kc1 Bh2 87. Kd1 Bg1 88. Ke1 Bh2 89. Kf1 g4 90. Ke1 Bg1 91. Kd1 Bh2 92. Kc1 Bg1 93. Kb1 Bh2 94. Ka2 Bg1 95. Ka1 Bh2 96. Kb1 Bg1 97. Kc1 Bh2 98. Kd1 Bg1 99. Ke1 Bh2 100. Kf1 g6 101. Ke1 Bg1 102. Kd1 Bh2 103. Kc1 Bg1 104. Kb1 Bh2 105. Ka2 Bg1 106. Ka1 Bh2 107. Kb1 Bg1 108. Kc1 Bh2 109. Kd1 Bg1 110. Ke1 Bh2 111. Kf1 g5 112. Ke1 Bg1 113. Kd1 Bh2 114. Kc1 Bg1 115. Kb1 Bh2 116. Ka2 Bg1 117. Ka1 Bh2 118. Kb1 Bg1 119. Kc1 Bh2 120. Kd1 Bg1 121. Ke1 Bh2 122. Kf1 Bg1 123. Kxg1 Kg7 124. h8=Q+


Is it improper etiquette to ask your opponent what his/her rating is before the game?

Yesterday, I played a tournament match, and at the table next to me the guy asked his opponent for his rating. “I don’t really know...” was the reply, “about 1580, I think. And yours?”

“Euhm... about 1400”, the guy mumbles in reply.

If you don’t want to give out your exact rating in reply or you don’t know it yourself, I would not ask the question to begin with. Furthermore, I thought the question was bad etiquette and would not really be happy with my opponent asking it.

Finally, where I live, most tournaments have lists of all participating players and their rating which you can look at. So start the game, and then after a couple of moves, when your opponent is thinking, you can always go check the list.

PS: I find that I play better when I don’t know my opponent's rating. Once I know his rating is a lot better, I get nervous and consider myself lost from the start. When I know his rating is much lower, I tend to play reckless and make mistakes.


Is playing stronger oppenents useful as a beginner?

As long as you're also playing players of your rating (and lower) along with the higher rated players it's okay. You don't want to be discouraged by losing every single game you play. Ideally you want to play people higher rated than you more than lower rated because it's like getting a free lesson - a higher rated player will be able to take advantage of your mistakes more than a lower rated player.

At a 800 rating, you'll want to focus on basics (basic opening principles, tactics, safety, thinking processes etc.) and review your games for common mistakes to pinpoint weaknesses and then eradicating them.

Of course, you'll also want to play slow time controls more than fast time controls as you want to be able to think about your moves and then be able to go back and correct your thinking. Faster games involve a lot of intuition and at your rating you won't really have a lot of it. So you'll want to develop that by playing slow time controls. Besides, you don't want to mess up games and then excuse yourself by saying that you didn't have enough time on your clock.

Also, you should begin reviewing some (master) chess games. A decent beginners book is Logical Chess by Irving Chernev. Don't review modern GM games yet as those are generally a lot more difficult to understand.


Which is the World's largest chess club?

Marseille Échecs (831 members)

According to the French Chess Federation, Marseille Échecs is the largest French club, totaling 831 officially registered players.

Two other French clubs have more than 500 members, in the cities of Bois-Colombes (612) and Villepinte (584), both near Paris.


Speed of minimax with alpha beta pruning in chess engines

There're some problems with your question:

Alpha-beta pruning doesn't make you search faster, it makes you search further. For illustration (these numbers are not accurate) if your computer is searching at 1 million nodes (here a "node" is a position) per second, without alpha-beta pruning you might only make it 5 ply deep. With it, you might reach 10 ply.
Obviously, how fast you search is going to depend on hardware. With sufficiently powerful hardware you can search 1.8 billion nodes per second. For example right now, Fishtesting is running with this hardware: 650 machines 5048 cores 1.21M nps (6127.86M total nps) 8825 games/minute. That's 6.1 billion nodes per second.
However note that Fishtesting is running with 5048 cores. A typical desktop computer might have 4 cores, so this is fantastically powerful hardware. If you're getting 1.8 billion nodes per second, and you have reasonably normal hardware, your eval function is probably very simple compared to the top engines.


Strategy in middlegame from boring positions

"Tactics is knowing what to do when there is something to do. Strategy is knowing what to do when there is nothing to do." -- Savielly Tartakower

What follow are the most salient features of the position that jump out at me, and these are the sorts of things one needs to look for when there seems to be nothing to do:

You have no structural weaknesses yourself.
Black has a weak backward pawn on the c-file that could become a very nice target.
Black can attack down the semi-open b-file, but that's less significant since the move b3 leaves White's pawn secure.
At the moment, Black's bishop pair isn't of much use due to the relatively closed nature of the position.

Having noted those things, it's safe to say that Black would love to get in the freeing move ... c5, which would allow her to exchange off her most significant weakness, while also starting to open up the position for her bishops. So a good course of action for White here is to try and prevent that move from Black, or at the least to make it as disadvantageous for her as possible.

With that in mind, a good start is 1. Na4, which leaves both the knight and the Qc2 eyeing the c5 square (and opens the way for the rooks to bear down on it as well), and doing so with tempo thanks to the attack on the Qb6. After 1. ... Qb7 2. Rac1 Rfc8 (note: it's these rooks in particular because White might want his other rook being able to go to the d-file if ... c5 -> dxc5 occurs, and Black might want her other rook to have access to the b-file), we see Black trying to support the ... c5 break and White trying to stop it.

[fen "r4rk1/p2nbp1p/1qp1bpp1/3p4/3P4/2NBPN2/PPQ2PPP/R4RK1 w - - 0 1"]

1. Na4 Qb7 2. Rac1 Rfc8 3. Qe2 a5 4. Rfd1 c5 5. dxc5 Nxc5 6. Nxc5 Bxc5

In this case, Black cannot be prevented from achieving the desired pawn break, and so White will need to switch gears and find new goals. For instance, here 3. Qe2 (threatening Ba6) ... a5 4. Rfd1 is a good idea (as mentioned before), so that we will be well-positioned after dxc5, with our rook on the newly half-opened d-file pressuring Black's isolated pawn. For instance, play might proceed 4. ... c5 5. dxc5 Nxc5 6. Nxc5 Bxc5:

[fen "r1r3k1/1q3p1p/4bpp1/p1bp4/8/3BPN2/PP2QPPP/2RR2K1 w - - 0 1"]

1. h3

Now Black's bishop pair is improved, but d4 is an inviting outpost for the white knight. If Black were to trade the dark bishop for the knight after it lands on d4, and we could recapture with a piece, then our structure and our bishop would be significantly better than Black's remaining one, and we would have good prospects for strong pressure against the isolated d-pawn. With that in mind, a good next step is 7. h3, which prevents Black playing ... Bg4 and trading off that bishop for our knight instead, and has the side benefit of creating luft for our king. Unfortunately for us, everything is basically level, as Black has ideas like playing ... d4 herself to open up her bishops and rid herself of her remaining weakness.

Anyway, I hope this gives you some idea of the kinds of thought processes that can be fruitful in "boring" positions like this one, the kinds of features that you should be thinking about when you're not calculating tactical possibilities (which you can never forget about!), and the sort of improvements that White could aim for from your initial position if Black were to fall asleep at the wheel.


If you are in Zugzwang, by definition, there is nothing you can do, because any possible move leads to a disadvantage.

Most typically Zugzwang appears in endgames with few pieces, particularly in pawn only endgames where is is used as a very common technique. I believe that if you study pawn endgames you should encounter it very often and get very familiar with it, so that you can keep it at the back of your mind when doing calculations.

I would not focus my endgame on avoiding Zugzwang as there are usually other things to take into account as well.


Flipped boards are useful when the observer is supposed to control or think as if he were controlling the black pieces. That makes sense because in on-the-board games you play the perspective of white if you're white, but play the perspective of black if you're black, so in the latter case you see a flipped board. It seems pretty reasonable to me.

And why don't they ever rotate the diagram 90 degrees to give us the kibitzer's (spectator's) view of the board?

The most likely reason is that players are simply not as comfortable with that view as with ordinary 0, 180° degrees view (people play more than they watch games).


I highly recommend Scid ("Shane's Chess Information Database"). Here's a screenshot of the Mac version (more to be found at Softpedia):

It is completely free, has lots of functionality, and is fast (handles my 5.2M game database quickly and fluidly). I have only used Scid in its Linux and windows versions, not the Mac. But from what I understand there are no appreciable differences in the software across these operating systems, and I've certainly never noticed any real differences between the Linux and windows versions in my own use. A few notes:

1. Scid cannot open .cbh files directly, but you should be able to use the ChessBase products you've been using to export to PGN, which Scid can then import into databases in its own format.

2. This doesn't apply to you, but for those who have never owned ChessBase but do have some ChessBase files that they'd like to import into Scid, there is a way to do so without buying any ChessBase products, at least on a PC. The old Fritz 5.32 is now freeware, and can be used to convert ChessBase files to PGN. (Amazingly, I know of no other free program that can do this; maybe someone else does.)

3. Scid plays very well with chess engines for use in analyzing games. I have Houdini 1.5 (the free version before it went commercial with 2.0), some version of Stockfish (free), and some version of Crafty (free) in use with my Scid.

4. One potential drawback, but only if you're on an older OS X: you can download the Mac version here, and it is pointed out there that the executable is available only for Mac OS X 10.5 or later; if you're using an older version, you'll have to build the program from its source code. They have instructions for doing so though, so it might not be too big of an issue anyway.

5. While I'm at it, I'll point out that some other developer made a free android app called Scid on the go, which I have used on my android tablet. It's scaled down from regular Scid quite a bit, and I've really only used it in a read-only way (data entry's not really fun on a tablet anyway IMO). But I have my big games database synced across devices using Dropbox, and it's nice to be able pull up games when I've only got my tablet with me.

I'll end by adding that Scid is the only database program I've ever really used, so do know that my recommendation comes without me having much experience with ChessBase or other commercial alternatives to compare it to. But that's also because I've never had any reason to; Scid really is great, and again, all the software I've mentioned here is completely free.


I think the Cochrane gambit is sound enough:

[FEN ""]
1.e4 e5 2.Nf3 Nf6 3. Nxe5 d6 4. Nxf7!?

Also the Evans Gambit:

[FEN ""]
1.e4 e5 2.Nf3 Nc6 3.Bc4 Bc5 4.b4

The Marshall counter-gambit in Ruy Lopez, sacrifices are pawn and gives black a good attack. However, it seems that some Grandmasters are using it as drawing tool, but for us black should have an attack.

[FEN ""]
1.e4 e5 2.Nf3 Nc6 3.Bb5 a6 4.Ba4 Nf6 5.O-O Be7 6.Re1 b5 7.Bb3 O-O 8.c3 d5 9.exd5 Nxd5 10.Nxe5 Nxe5 11.Rxe5


According to the Scid vs PC help use menu options:
Options / Moves / Show Variation Arrows


You can find Philidor’s 1790 book here in a free Google Books scanned eBook of it.


What type of tournament is needed to get a true chess rating?

A "real" rating is gained by joining the USCF and playing rated tournaments.  You can get a rating from any USCF sanctioned tournament.  They don't have to be all-weekend tournamants; I've played in several G30 tournaments that had 3 rounds in one evening.  In addition, you and an opponent can play a rated match if a USCF tournament director approves it.

You can also get a (non-USCF) rating by playing on one of any number of internet sites.

EDIT - here are some clubs in Orlando.  I recommend you join one and mingle.  The first one here has USCF tournaments...

ORLANDO FL 32810 FL. CENTRAL FLORIDA CHESS CLUB (USCF ID A6007091). Affiliate Type: Club. Call for information. Call for information, ORLANDO FL 32810. Contact: HARVEY LERMAN. Contact Phone: 407-644-3542. Club Phone: 407-629-6946. Address: C/O HARVEY LERMAN, 921 N THISTLE LANE, MAITLAND, FL, 32751-3736. email: harveylerman@embarqmail.com. Web Site: www.centralflchess.org, Club Membership Not Required, Casual Play, USCF Rated Events, Blitz Events, Club Championships, Private Lessons Offered, Under Age 18 Welcome, Prison chess support. (Crosstables from past rated tourneys for this affiliate)

ORLANDO FL. ORLANDO CHESS & GAMES CENTER (USCF ID A6018039). Affiliate Type: Club. 10AM-10PM MON-SUN. 8853 COMMIDITY CIRCLE, ORLANDO FL 32819, ORLANDO. Contact: ALEX ZELNER. Contact Phone: 407-248-0818. email: alex@orlandochess.com. (Crosstables from past rated tourneys for this affiliate)

from this page.


High quality resource for Exchanged Slav defense?

Let me preface this by saying that I have not kept up with new publications in about a year, but there was nothing that I knew of before that.

My educated guess is that the only real "modern high quality resource ( for players 2400+ ) that covers this line" is going to be GM games. Here are my reasons for that:

1) Vladimir Kramnik-the most influential figure in chess opening theory over the last 15 years-played a significant novelty in this line. This means that other players, from the top level down to lower GMs (which is about the lowest you can go and still have the games be considered part of Theory without further examination) have probably taken to copying him and extending the line. Even if you did find a comprehensive book published 8 months ago by some mid-level GM, there could well be some game between two 2600s from 2 months ago which changes the outcome of a variation. A prepared opponent will surely know about that and the book will not.

2) You are at a level where, since you already have a solid foundation in the line, you are probably better off looking at the games that a book would present to you and drawing your own conclusions. People like Vigorito who are about your strength and publish books are basically doing the exact same thing you could be doing-applying computer analysis to positions, recognizing the ideas, and memorizing/writing down the result. People that play for a living and create theory will be more concerned with protecting novelties and using them to win games (thereby giving them to you for free) than adding them to a book to see a tiny bump in circulation.

I am not saying that there are no groundbreaking books by top players. Avrukh's repertoire series for White was incredibly well-researched and included dozens of novelties. Victor Bologan has written 3 influential books on various lines. These books are rare, though, and a large majority of theoretically-relevant openings do not have resources of similar quality. You can construct better opening knowledge by doing your own research.


How does an engine decide which node to search first?

http://rebel13.nl/rebel13/ideas.html explains this well.

The basic idea is to order the moves based upon what the program thinks is the best move without searching.  This score is usually based upon mobility, piece-square value, center control, history, attacking potential, captures, and other elements the programmer thinks is important.  Just as humans base their candidate moves based on intuition and history, the computer searches the highest scoring move first.

If the computer is limited to only five nodes, then yes, the computer will only search the five highest scoring moves.  This time limit factor could cause to computer to miss a mate-in-one if it was scored poorly.  The first method to correct for this was to establish fail-safes.  These would cut short a search if the position became noticeably worse or significantly better.  The hope was to allow for more time to search more variations that might use the time better.  Other search algorithms, iterative deepening,  have improved the time management as they have a shorter length before they enact a fail-safe.


Variation of Attack besides Center Control and Flanking

Attacking isn't necessarily generalized to areas of the board. For example, I can attack your queen with my pawn, and this isn't a localized concept. Your question seems to imply that you're asking about attacks on the opposing king as you specify attacking the side of the board where your opponent has castled. There exist far more aggressive strategies than controlling the center or flanking out the opponent. Consider tactics, square and file control, general initiative, and development as alternatives.


I feel you should choose an opening repertoire so you enter middlegames where you (a) know where the pieces belong ordinarily, and (b) understand the plans in those openings.  At a certain point, you need to do more than "just develop".

If you've ever watched a GM give a video lecture on some opening, you'll see them repeatedly avoid certain lines not because they're "bad", but because there is no clear plan for what to do.  And I can't tell you how many games I've lost simply because I got to a position with my pieces all on their seemingly best squares, but without a plan for how to continue.  I make random moves that don't immediately lose, but it makes things incrementally worse.

For example, a straightforward plan arising from an opening (that works from beginner to super GM level) is the minority attack.  Here's one of many examples:

[FEN ""]
[Date "1994"]
[Round "2"]
[White "Karpov (2780)"]
[Black "Campora (2560)"]
[Result "1-0"]

1. d4 d5 2. c4 e6 3. Nc3 Nf6 4. cxd5 exd5 5. Bg5 Be7 6. e3 O-O 7. Bd3 Nbd7 8. Nf3 c6 9. Qc2 Re8 10. O-O Nf8 11. h3 Be6 12. Bxf6 Bxf6 13. b4 Rc8 14. Na4 Rc7 15. Rac1 Be7 16. Qb1 Bd6 17. b5 Qf6 18. bxc6 bxc6 19. Nh2 Qh4 20. Bf5 Qh5 21. Bxe6 Nxe6 22. Nf3 f5 23. Rc3 Nd8 24. Nc5 Bxc5 25. Rxc5 Ne6 26. Rc3 f4 27. e4 h6 28. Re1 Rce7 29. Rxc6 dxe4 30. Rxe4 Qd5 31. Rc3 Qf5 32. Qe1 Qd5 33. Kh1 Qd6 34. Qd2 Ng5 35. Rxe7 Qxe7 36. Qxf4 Qb4 37. Nxg5 hxg5 38. Qd2 g4 39. hxg4 1-0

In this game, white's plan after development is a minority attack: to push the queenside pawns, and give black a pawn weakness, which should give white an edge in the endgame.  We see on move 18, black ends up with a backwards pawn.  White heads for an endgame by swapping off pieces, while black tries to stir up trouble with the f-pawn push.  On move 28, black gave up defending it (rather than waste a rook defending a pawn), and let white capture it.

The moral of the story: choose openings so that your plan is clear.


Does a non-copyrighted scoresheeet exist that I can print out instead of purchasing pre-printed sheets?

I have a scoresheet I created for my own use here:

https://docs.google.com/folder/d/0B4uNw3C8V0SDZjZneGVUVTVaNlU/edit?usp=sharing

I have pdf versions in various colors and the MS Publisher file I used to create it.  So if you have MS Publisher you can modify it.

The readme.txt file in that folder has descriptions of the files.


What are the shortest possible games with a) 20 Bishops, b) 20 Knights, and c) 20 Rooks?

Addendum 1/9/2021: In a Computer Chess Club archives page that I came across today, I found some holy grails! The thread author Eduard Nemeth posted four proof games, all from 1997 and by Zoltan Blazsik, for 18 queens and 20 rook, bishops, and knights.
The bishop and knight games are faster than mine-new records! However, my 104 ply for 20 rooks remains untouched.
[Title "20 Knights-100 Ply, Zoltan Blazsik, 1997, Non-Unique Proof Game In 50.0 Moves"]
[FEN ""]
[startply "100"]

1. h4 g5 2. h5 g4 3. h6 Bg7 4. Rh3 gxh3 5. hxg7 h5 6. b4 a5 7. b5 Ra6 8. bxa6 a4 9. a7 a3 10. Bb2 axb2 11. a4 h2 12. g4 e5 13. f4 d5 14. e4 Be6 15. f5 h4 16. fxe6 f5 17. g5 h3 18. c4 Qd6 19. c5 f4 20. cxd6 c5 21. Bc4 dxc4 22. d4 c3 23. d5 c4 24. Qd4 exd4 25. a5 bxa1=N 26. a8=N c2 27. a6 c1=N 28. a7 c3 29. gxh8=N b5 30. Nb6 b4 31. a8=N b3 32. Na3 b2 33. e5 b1=N 34. g6 Na2 35. g7 Nh6 36. g8=N c2 37. d7+ Kf8 38. d8=N c1=N 39. e7+ Kg7 40. d6 h1=N 41. d7 h2 42. Nb7 d3 43. d8=N d2+ 44. Kf1 f3 45. e8=N+ Kh7 46. e6 f2 47. Kg2 d1=N 48. Nec7 f1=N 49. e7 Nhf2 50. e8=N h1=N

[Title "20 Bishops-100 Ply, Zoltan Blazsik, 1997, Non-Unique Proof Game In 50.0 Moves"]
[FEN ""]
[startply "100"]

1. a4 b5 2. a5 c5 3. Ra3 b4 4. d4 Qb6 5. axb6 a5 6. d5 Nc6 7. dxc6 bxa3 8. b4 a4 9. b5 c4 10. Nd2 c3 11. e4 f5 12. e5 Nf6 13. exf6 f4 14. g4 h5 15. g5 Rh6 16. gxh6 g5 17. h7 g4 18. h4 g3 19. Qg4 hxg4 20. h5 g2 21. h6 gxh1=B 22. Ne2 f3 23. h8=B fxe2 24. f4 g3 25. b7 g2 26. f5 e5 27. bxa8=B cxd2+ 28. Kf2 a2 29. c4 a1=B 30. b6 d5 31. b7 d4 32. c7 g1=B+ 33. Kg3 a3 34. c5 a2 35. b8=B Ba6 36. c8=B Bb2 37. c6 a1=B 38. Bcb7 d1=B 39. c7 Bb3 40. c8=B d3 41. f7+ Kd8 42. f6 Bb4 43. f8=B d2 44. Bc5 e1=B+ 45. Bf2 d1=B 46. f7 e4 47. h7 e3 48. Bg7 e2 49. h8=B Bed2 50. f8=B e1=B

Thanks to Remellion's comment that getting 16 passed pawns first isn't necessary, I shaved 2 plies off 20 knights.
Addendum 11/29/2020-With a Black king maneuver, another ply is gone.
[Title "20 Knights-101 Ply, me, chess.stackexchange.com 11/29/2020, Non-Unique Proof Game In 50.5 Moves"]
[FEN ""]
[startply "101"]

1. h4 a5 2. h5 a4 3. b4 g5 4. h6 a3 5. Bb2 Bg7 6. hxg7 axb2 7. a4 h5 8. Rh4 Ra5 9. bxa5 gxh4 10. g4 b5 11. g5 b4 12. g6 b3 13. c4 f5 14. c5 f4 15. c6 f3 16. Bg2 Bb7 17. cxb7 fxg2 18. gxh8=N bxa1=N 19. f4 c5 20. f5 c4 21. f6 c3 22. g7 b2 23. a6 h3 24. a7 h2 25. a8=N h1=N 26. a5 h4 27. a6 h3 28. a7 h2 29. e4 d5 30. d4 e5 31. Qf3 Qc7 32. Qf4 Qc5 33. dxc5 exf4 34. e5 d4 35. e6 d3 36. c6 d2+ 37. Ke2 f3+ 38. Ke3 f2 39. c7 c2 40. c8=N c1=N 41. e7 f1=N+ 42. Kd4 Na6 43. f7+ Kd7 44. e8=N Nh6 45. Nh3 g1=N 46. Na3 b1=N 47. Nac7 Nhg3 48. a8=N d1=N 49. b8=N+ Kd8 50. f8=N h1=N 51. g8=N


Probability of given position/piece configuration

Utilizing a chess engine: We utilized the open-source Stockfish engine, which allows us to calculate the most probable piece configurations. By calculating the prob-abilities of all possible configurations, we could choose the most probable candidate (see Figure 7). Additionally, we strengthened this method by utilizing large-scale chess game statistics in the manner proposed by Acher and Es-nault Acher and Esnault (2016).

This makes literally no sense to me- SF is just an engine, and can't exactly give stats on most probable piece configs, and even if the researchers wrote some code to do such, it would be different than the most probable ones in human play.
My suggestion would be to use CQL on some database and search for each configuration.
Alternatively, SCIDvsPC (free) and ChessBase (paid, and quite expensive) can search for these sort of configurations as well, so you might want to use those.
As for what database to use, my recommendation would be Caissabase (free)


Is the following Knight sac in the Sicilian Najdorf justified?

I ran this through Stockfish at 15 minutes per move. What I have found is that the sacrifice is sound and wins.  But for a 'won' game, it is about the hardest road I have ever seen.  The evaluation of the position is less than a pawn advantage for White up through move 25 or so.

The sacrifice leads to opportunities for White, but both sides are walking the razor's edge.

[FEN "r1b1kb1r/1p1n1pp1/pq2p2p/4p3/2BN1P2/2N2Q2/PPP3PP/2KR3R w kq - 0 1"]

1.Nxe6 fxe6 2.Qh5+ Kd8 3.Qf7 Qe3+ 4.Kb1 Qxf4 5.Qxe6 Qf6 6.Qh3 Bc5 7.Rhf1
Qc6 8.Bd5 Qg6 9.Bxb7 Ra7 10.Be4 Qe8 11.Nd5 Rf8 12.Qh4+ g5 13.Qxh6 Rxf1 14.
Rxf1 Bb7 15.Qxg5+ Kc8 16.h4 Qd8 17.Qg3 Bxd5 18.Bxd5 Kb8 19.h5 Rc7 20.Rd1
Ka7 21.Be4 Qf6 22.Qg4 Nb6 23.Qf5 Qg7 24.a3 Be3 25.g4 Bf4 26.Rd6 Nc4 27.Rg6
Qd7 28.Qxd7 Rxd7 29.Bd3 Nd2+ 30.Ka2 e4 31.Be2 Kb8 32.g5 Nf3 33.Rg8+ Kc7
34.g6 Kd6 35.Rh8 Nh4 36.Bxa6 Be5 37.Re8 e3 38.b4 Nf5 39.Rf8 Ra7 40.Bd3 Nd4
41.h6 Nxc2 42.Kb1 Nxa3+ 43.Kc1 Re7 44.h7 Nc4 45.Rd8+ Kc7 46.Rg8 Nb6 47.
h8=Q Bxh8 48.Rxh8 e2 49.Bxe2 Kd6 50.Kd2 Rg7 51.Bd3 Nd5 52.Rd8+ Ke5 53.b5
Nb6 54.Rf8 Ke6 55.Ke3 Rb7 56.Kf4 Ra7 57.Kg5 Ke5 58.Kh6 Rd7 59.Rf5+ Kd4 60.
g7 Rd8 61.Rf8 Rd6+ 62.Bg6 Kc5 63.g8=Q Kxb5 64.Qb3+ Kc6 65.Qc3+ Kb7  66.Rf7+
Nd7 67.Qc5 Rd1 68.Re7 Rh1+ 69.Kg7 Rh7+ 70.Bxh7 Ka6 71.Bd3+ Kb7 72.Rxd7+
Kb8 73.Qf8#

The general method of White's win isn't a Tal-like knockout, but instead we find that Black cannot hold onto the Kingside pawns. They drop off allowing White connected outside passers.    Black has plenty of resources however.  In return, Black gets a passer on the e-file that will be a real threat.  Black also eats two of the three pawns on the Queenside. I think this passer is one too many, and it's going to kill him.

After 2. Qh5+, Black's King is stuck in the middle of the board. This will be a
lodestone that will haunt Black for the rest of the game.  Yet another example of
what happens when the weak f7 square is exploited.  This is really the lesson of
this sacrifice - "Weaken the f7 square and you might just get some traction."

3. Qf7 and the White Queen is in Black's business.

After move 5, we see White's side is orderly, his two minor pieces are developed,
his King is secure, and his Rooks are ready to leap into action.  Charitably
speaking, one of Blacks minor pieces is developed.  His Rooks are still in the
box, and one Bishop is entombed.  Black is trying to trade off the Queens.
If he does, he wins.  When one has a material advantage, it's generally best to
trade off pieces. Of course, White is having none of it.

6... Bc5  Black must develop. Now his Bishop matters and he can activate his Rook.

Up to move 9, White harasses the Black Queen developing a Rook with tempo, then
picks up the loose b pawn.  This allows Black Queen Rook to enter the game, but
now Black as 2 isolated pawns to defend.

10... Qe8 To this point, Black has managed to swap his King's and Queen's positions!
White's Rooks control two open files and has a big grip on the center.  The Rook on
d1 is a monster, holding the center, pointing at the exposed Black King while pinning
the Knight in the process.  Remember, if Black can't use the Knight, it does not really
exist, and thus White is, after a fashion, not down any material.

11... Rf8 challenges White's f Rook.  The cost is terrible - the remaining pawns
on the kingside.  12. Qh4+ is frightening, exposing Black's folly.  At this point, it's
worth pointing out how the computer is very particular with tempo.  Instead of an
immediate Rook trade White throws a
check first - again hitting the misplaced King and cause Black to further weaken himself.
Amusingly (for White) the Black Knight is still immobile.  If he moves it to,
say b6, Rf8 wins.
I would be interested to see peoples' alternatives to 11... Rf8.

15. Qxg5+ White scoops up the other pawn, with tempo, adding insult to injury.
The immediate 16. h4 is the signal Black's in for a long day.

17... Bxd5 Black has finally completed his development though White has the
open file and the majority of the center.

20. Rd1 Back to the center, now pressuring the Queen.

23. Qf5 White now offers the Queen trade which is declined.  This is another point
in the game where a variation could be helpful.

Through move 26, Black's defensive play is quite good.  He's a tempo from picking up the
pawn on g4.  White's 27. Rg6 supports g4 again with tempo.  This move does
three things: it threatened the Black Q, defends g4, and frees the White Q to run if
Black were to play Ne3.

Through move 29, the Queens drop off, Black claims the d file, and White blocks it
with his Bishop, simultaneously preventing a nasty Knight fork on d2.  Such economy!

30... e4 Black has threats, too.  Black's play is a great lesson on how not to give up.
White is one bad move from losing this game.

31... Nf3 wins the g pawn?  Nope, White checks with tempo allowing the jammed pawn
to move out of danger.  Again, seeing alternatives to 31...Kb8 would be interesting.

35...Nh4 looks goofy as it allows the a-pawn to drop off.  But it's lights-out if White
is allowed to play h6.  In that case, White wins the Black Bishop and threatens a
discovered check with g7.  Economy!

You might think Black should just resign. And maybe he should.  Now let's look at the
defensive resources that are available to him.

First, Black's e3 hits White where he isn't.  That pawn is scary.  Only the Bishop
is saving White.  Black attacks it. If the Bishop is driven off the a6-f1 diagonal,
Black wins or draws.

41. h6 computers are cool under fire.

41... Nxc2 if Bxc2, White loses.  Now the threat is Nxb4+ where white's defending
Bishop drops off, and it's mayhem that favors Black.

42. Kb1 the Bishop needs help.  White must now pay the Butcher's Bill.

44. h7 White pours on the pressure, but Black's Bishop and Rook combo is very effective.

44... Nc4 is hard to understand.  Perhaps it is one of those moves that moves a bad
evaluation out one move.  Some thought here is needed.

49... Kd6 is a great example of an inhuman computer move, where the machine is making choices about fractions of pawns.  The alternative is 49... Rxe2 50. g7 Rg1 51. g8=Q Rxg8 52. Rxg8 and Black has lost the exchange for a pawn.  I would like to know why Black played 48... e2 at all.

Finally, to answer the OP's question, is the sacrifice justified?  That's a value judgement.  If I played this as White, and won, it would easily be the hardest win in my 'career'. A win is good, but this game is a hard, risky win. If one is willing to walk the razor's edge and one is good at managing one's clock, a point's a point.

This could be one of those games where one side has to play MUCH better in order to hold. That is, maybe White has to play like a master to hold, but Black can play like an 'Expert' to draw.  That is, whoever missteps first, loses, and White has more land-mines to avoid.

If anyone has alternate variations they'd like me to run, let me know.


Algebraic notation avoiding ambiguity rank or file preference

This would be Qfxd3.

From wikipedia (emphasis is mine):

  When two (or more) identical pieces can move to the same square, the moving piece is uniquely identified by specifying the piece's letter, followed by (in descending order of preference):

  the file of departure (if they differ); or
  the rank of departure (if the files are the same but the ranks    differ); or
  both the file and rank (if neither alone is sufficient to identify    the piece—which occurs only in rare cases where one or more pawns
  have promoted, resulting in a player having three or more identical
  pieces able to reach the same square).


From the cited Wikipedia article:

  The strategy of protecting a pawn or specific square of the chessboard more than is immediately necessary. This serves to dissuade the opponent from attacking that specific point and provides greater freedom of movement for the pieces protecting that square.

The sense in which overprotection provides "greater freedom of movement for the pieces protecting that square" is that, with multiple defenders already in place, no one of them is necessarily tied down to defense.

What follows isn't the greatest example, but I think it illustrates the concept fairly well. (I'm not claiming any of these moves are the best or are necessary; I've chosen them specifically to illustrate overprotection.)

[FEN "r1bq1rk1/ppp1npbp/3p1np1/4p3/2P5/2NPP1PP/PP2NPB1/R1BQ1RK1 w - - 0 1"]

1.Kh2
    {Overprotecting h3, and thus creating a genuine threat against b7 by
    the Bg2. That makes it so that the Bc8 can't develop immediately.}
    ( 1.Rb1 {In this variation White leaves the Bg2 as the only defender
    of h3, and so Black can immediately develop the Bc8 if she likes.}
    1...Be6 2.Bxb7 Bxh3 3.Bxa8 Qxa8 4.e4 Bxf1 5.Qxf1 )
1...Rb8
    {Black responds by overprotecting b7 herself. Again, having this
    second defender frees the Bc8 to develop.}
    ( 1...Be6 $2 2.Bxb7 )
2.Rb1 Be6

The Wikipedia entry continues:

  [Overprotection] can cause an opponent to pursue a faulty plan or no plan at all.

I'm not sure about that wording, but I think the intended meaning is this: the opponent might press on against the overprotected piece/square in what will be a futile attempt thanks to the overprotection (faulty plan) or will be forced to abandon that endeavor and look for something else to do (no plan at all).

For example, in the basic structure of my position above, it is very common for Black to line up a Be6 and Qd7 to harass the h3 pawn (or just try to trade off the light-square bishops if the pawn is still on h2); but once White has played h3 and Kh2 as above, Black won't really be able to effect that plan. She might press on and ultimately be unsuccessful (faulty plan), or instead need to figure out something else to do in the position (no plan).