My opinion (!) is that the rules are clear and correct.
Checkmate is not allowed when the move involves moving a piece in a way that the piece may not move (e.g. moving a bishop like a knight) and not allowed when touch-move rules are broken.
However checkmate IS allowed when a procedural rule which is intended to stop clock cheating is broken. This is because pressing the clock in the case of checkmate is not required. The two-handed rule is intended to tidy up the requirement that the clock is pressed with the same hand that makes the move. In cases where pressing the clock is irrelevant then so too is the use of two hands. Hence why 4.1 is deliberately and carefully excluded from 5.1.1
The rules commission obviously thought of this and, collectively, they are cleverer than both you and me :-)
Note, too, that the same logic applies to stalemate and "dead positions". This careful thought by the rules commission is reflected in the relevant articles:

5.2.1  The game is drawn when the player to move has no legal move and his king is not in check. The game is said to end in ‘stalemate’. This immediately ends the game, provided that the move producing the stalemate position was in accordance with Article 3 and Articles 4.2 – 4.7.

5.2.2 The game is drawn when a position has arisen in which neither player can checkmate the opponent’s king with any series of legal moves. The game is said to end in a ‘dead position’. This immediately ends the game, provided that the move producing the position was in accordance with Article 3 and Articles 4.2 – 4.7.

There is one further area that this clarifies. Suppose that the player delivering checkmate with two hands has previously made an illegal move and does press the clock after delivering checkmate. They still win the game because the game ended with the checkmate, before the completion of the move with the clock press. Hence the second illegal move was made but not completed and only completed illegal moves are punished.


Why is the latest Stockfish (2.2.2) infinitely slower (than 2.1.1) in Scid?

So, I hashed this out some in a support thread on the stockfish forum.

Basically, you should skip 2.2.2 and compile the latest from github (or just continue to use 2.1.1). I think I'll try this new code for a while to see how it does. The latest code from github works great in chesstempo's UCI connector. It's still a little slow out of the gates in Scid (and Scid acts like it's hanging and doesn't respond to UI commands), but it speeds up as it gets deeper in the search, so it's bearable after 30 seconds or so. I had trouble getting multipv (multiple variations) to work at high numbers, though.

I think Scid should not block the input from the UCI interface--buffering more, if need be. Maybe I'll take a look at the Scid code later to see if I can improve it.


Statistically, what is the best opening?

Here is a tongue-in-cheek answer. The 4 move checkmate (1. e4 e5 2.Qf3 Nc6 3.Bc4 Bc5?? 4.Qxf7#) is an opening where White has won 100% of the time.

The reason why I post this answer is to highlight a few flaws in the question you asked:

Maybe if you find an opening with a high win ratio, you will build your reportaire around it? This is flawed logic as Black can sidestep your preparation, which may lead you into a bad line. Instead, play the openings that feel right for your playing style
What is an opening? Ultimately the opening are just the first few moves in the game. Crucially for a statistical question, you didn't say how many moves you are looking at. The first? The first 10? Assuming best play with Black? In most chess games, there are many moves other than those in the opening stage that determine the outcome of the game. I'd suggest you concentrate more on the middle and endgame than the opening


Why is 5. Bd3 considered a strong move against the Kan variation?

The difference is that in the Kan white exchanges the knight on c6. In other sicilians this would be a concession, but here black has already played a6, which will not be particular useful after Nxc6 bxc6. In the other sicilians, if white doesn't exchange the Nc6, it will often go to e5 and threaten to exchange a Bd3, that's why the bishop often isn't well placed there. The plan connected to Bd3 is of course to play e5 sooner or later.


A digital tree (with annotations) of all chess opening moves discovered by theoreticians

Did you ever find a tree like this?  I have a Chessmaster file that I have created that documents every move of every named opening line recognized by the program.  Yes, it took me ten years and spanned 4 computers and probably 5 versions of ChessMaster to complete...and yes, I do account for transitions...its very awkward to use sometimes when stepping through successive transistions because its sort of a manual process. Here are some screen shots...oh, and at the end of every opening line, I analyzed the final position, scored it, and walked the score back to the previous branch...I did this for every position where there are several candidate moves, all the way back to the starting position of the game...the first screenshot shows that result.  The second screen shot shows a position a few moves in (Note the references to possible transitions).  The third screen shot shows one of hundreds of thousand of ending positions I had chessmaster analyse

The .CMG file is 30 megabytes and I continue to expand it by adding in all the non-book moves I've encounted and explored as well...Sadly, I believe the file is actually reaching the limits set by the program and lately I've been losing work because the latest file I save frequently becomes corrupted and unusable (I back it up every few edits however, then back up the backup every few days).  But still there have been times where I have lost weeks of analysis and added chesslines.

Therefore, I'm looking for a new platform to migrate all this work to and to continue this project on a modern platform.  the .CMG format is probably 30+ years old now!  Definitely could be improved!


Can someone explain to me how I can develop my tactical ability, and what type of practice I should do?

Depending of where you are right now, there are a few steps, you may feel free to skip, if you think you've already good at that.

Get a good beginners' book, that explains basic stuff, pins, forks, discover checks and everything. Work on this book for a week, until you grasp the few general concepts most combinations are based on.  Solve all puzzles and answer all questions from that book, those might be "too easy", but it has to be done.
Get some application on your phone, become a member on lichess, maybe some other web sites, that offer chess puzzles for you to solve. Most important are applications, because they are more interactive and have a few crucial features that most web sites don't.
Get solving.
Track your progress.

Things you have to look for in apps/websites that will make your live easier:

Adaptive puzzle level, that tracks your score and does not bore you with simple problems, and at the same time does not start from 2200+ level hardcore stuff.
Various puzzles, including "mate-in-XX", and more broad "find the best move..." type of things. From where I sit, ALL problems have to be of the second kind, where you don't know if you're looking for a mate or just little material, like in the real game.
Preinstalled engine, that allows you to play any puzzle from any move, see what computer response is, learn from it. Sometimes puzzles can be not very obvious and / or have more that one variation you have to think about.
The ability to get a hint, and the ability to continue solving the puzzle once you made a mistake. Apps are a bit better in this aspect, than web sites.

What would I recommend? From the web sites -- lichess, they don't have pre-canned bunch of stale puzzles, they analyse the fresh games and make new puzzles from every blunder or mistake people make -- it's very refreshing, and with their 3+ million game database they'll never run out of puzzles.

iPhone/iPad apps -- don't know, maybe others will chime in.

Android -- I used "Chess Tactic Puzzles" (totally free) and "Chess Tactics Pro" (contains ads) -- these are two different apps from the different authors. Both include built-in engine for the analysis. "lichess" (free) has an app as well.


What are minimum number of moves needed to checkmate a king using king and rook?

According to this site, the worst case for King + Rook vs. King is the following position, requiring 16 moves to mate (White to move):

[FEN "8/8/8/8/8/2k5/1R6/K7 w - - 0 1"]

There are other positions which require 16 moves, e.g. with the White King on a1, Rook on e2, and the Black King on d3.

You can play these endgames with an online database viewer, e.g. Shredder.

The worst case scenario (for White) with Black to move is when Black is stalemated or can capture the rook, when it is a draw. With White to move, all positions are won.


What is the best strategy for an amateur to last as many moves as possible against a GM?

It really depends on what you mean by "lengthen".

I am not a GM, but as an "ordinary" Master, I have played 1700s before, who were lost by move 10, but the game still took 50 moves to finish. If you are trying to stay equal longer, that is a harder question to address.

If you are just taking about purely lengthening the game, then you are looking to trade material. Endgames naturally take longer to play out. Again, they may still be lost for many moves, but they can take 40-50 more moves to execute the opponent.

In reality, if you want a shot at being one of those statistical upsets, you want a complicated position, possibly at the cost of a pawn, where you are the aggressor. You are still likely to lose, but at least you have a "puncher's chance".

P.S. I do not recommend playing randomly. That is a recipe for making MUCH WORSE moves, which will be punished that much more severely. Unless it is an actual good move that is buried deeply, and that a strong player overlooked, a "random move" is really just a move that we discounted already, usually for good reasons. Playing moves that strong players do not consider strong, is not a good recipe for success. When I encounter such a random move, it is usually just bad, and I try to adjust to take advantage of whatever new weakness was created.

P.P.S. Based on your comment, and clarification, in the comment below, there is probably nothing you can do that will guarantee that you will stay equal longer other than if you have prepared the game with a chess database, and guess the line that the GM ultimately will play. A GM is going to be MUCH stronger positionally, and tactically. They simply analyze and understand much better.

That leads me back to my last comment above, and that is you want a complicated position. They will probably outplay you there too, but that is the only way you have a prayer.


What are the ideas behind the Blackmar-Diemer gambit?

I've used BDG countless number of times and won virtually everytime over weaker players. This is a dangerous opening if Black simply plays normal development moves, quite tricky to play in a 5-minute blitz game.

White has to attack because he is a pawn down. The most direct and surprisingly effective setup is:

Position the light bishop on the d3-h7 diagonal
Move the white queen d1-e1-h4
Prepare for an exchange sacrifice on the f-file
Prepare for bishop sacrifices on the h6 and h7 squares

Why is this effective in a blitz game? An unprepared Black player might just simply make normal development moves, as if there was no gambit. By the time Black sees the checkmate, it'd be too late. If Black plays h7-h6 or g7-g6, White has the the two bishops and f1-rook to do further damage, for example sacrificing by Bxh6.

This gambit can be refuted, possible ideas:

Castle to the queen-side
Delay castling and strike on the weak d-pawn. If white plays c3, Black has ...c5 to challenge the pawn and try to open the weak g1-a7 diagonal.

I've personally found very difficult to deal with Black castle queen-side, because it is harder to exploit the space advantage in the king-side while the Black king is on the other side of the board.

Here, I give a sample game that I've used many times.

[FEN "rnbqkbnr/pppppppp/8/8/8/8/PPPPPPPP/RNBQKBNR w KQkq - 0 1"]
1.d4 d5 2.e4 dxe4 3.f3 exf3 4.Nxf3 Nf6 5.Bd3 e6 6.O-O Bd6 7.Bg5 O-O 8.Qe1 Nbd7  9.Qh4 c5 10.Ne5 cxd4 11.Bxf6 Nxf6 12.Rxf6
*


Why isn't this threefold repetition, forcing a draw?

There is no such thing as "3 move repetition". To claim a draw, the position must be repeated three times (although it does not have to be in a row). In your example, the position with a Black queen and b4 and a White king on b2 has only occurred twice so far. You can claim a draw by repetition of position the next time that you can cause that position to appear.

If you make such a valid claim and your opponent refuses to honor it, he or she is not playing by the rules of chess. If you are playing on some computer service that does not recognize a valid claim of threefold repetition, the service does not implement the full rules of chess.


Searching for players by primary opening choice

The opening explorer at 365chess dot com shows which player played the position at hand most often, while also showing most recent examples.


According to Wikipedia:

Public

  The three significant public chess libraries are:

  The John G. White Chess and Checkers Collection at Cleveland Public
  Library has the largest chess and draughts [chequers for those in the
  US] library in the world, with over 32,000 chess books and over 6,000
  bound volumes of chess periodicals. It was started with the donation
  of a quarter of a million dollars and 11,000 books from John G.
  White's private library upon his death.

  The Chess & Draughts collection at the Bibliotheca Van der
  Linde-Niemeijeriana (part of the Koninklijke Bibliotheek, the National
  Library of the Netherlands). The second largest public chess
  collection in the world is built on the donations of the private chess
  libraries of Antonius van der Linde, Meindert Niemeijer and G.L.
  Gortmans. It contains about 30,000 books.

  The M.V. Anderson Chess Collection held at State Library Victoria
  (Melbourne, Australia) is the largest public chess collection in the
  Southern hemisphere. This contains in excess of 12,000 books and many
  journal and newsletter titles. Additional titles are added each year.
  It is based around M.V. Anderson's personal collection of 6700 volumes
  donated between 1959 and 1966.

Private

  Grandmaster Lothar Schmid of Bamberg, Germany reportedly owned the
  world's largest private collection of chess books and memorabilia. In
  1992, Hooper and Whyld stated that Schmid's chess library "is the
  largest and finest in private hands, with more than 15,000 items". In
  2008, Susan Polgar stated that Schmid "has over 20,000 chess books".
  Dirk Jan ten Geuzendam states that Schmid "boasts to have amassed
  50,000 chess books.

  David DeLucia's chess library contains 7,000 to 8,000 chess books, a
  similar number of autographs (letters, score sheets, manuscripts), and
  about 1,000 items of "ephemera". DeLucia's library contains such items
  as "a 15th-century Lucena manuscript, score-sheets ranging from
  Fischer's Game of the Century against Donald Byrne to all the games of
  the 1927 New York tournament, eight letters by Morphy, over a hundred
  Lasker manuscripts, Capablanca's gold pocket watch, [and] the contract
  of the 1886 Steinitz-Zukertort world championship match". Ten
  Geutzendam opines that DeLucia's collection "is arguably the finest
  chess collection in the world".

  Former World Champion Anatoly Karpov has a large chess stamp
  collection. He has a private chess library of over 9000 books.


What's the difference between a tempo and a tempi? At the start, how many tempo/tempi is White up? On average, how many tempo/tempi is one Pawn worth?

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

Tempi is the plural of tempo.

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

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

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

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

I'll give an example-

Consider this opening -

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

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

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

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

After Black's 4th move -

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

After Black's 6th move -

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

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

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

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

Here, Houdini's evaluation at depth 20 is

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

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

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

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


What is the best way to document and archive my past games?

I would recommend you to use a game database software, as Scid, Scid vs PC, ChessX, ChessDB, Scid on the Go (Android), etc.

I use Scid for all of that (documenting, archiving and analysing) and it works really well.


The bishop is pretty decent on g5 as well.

So after 1. d4 d5 2. Nf3 Nf6 3. Bf4 Nh5 4.Bg5 and now black would have to create serious weaknesses on the kingside to hunt down the bishop. But if he just returns the knight, he has lost a tempo.

[FEN ""]
1. d4 d5 2. Nf3 Nf6 3. Bf4 Nh5 4.Bg5 h6 5.Bh4 g5 6.Bg3 Nxg3 7.hxg3


Why is this a threefold repetition draw?

The position after 47.… g4, 49.… Kc8 could have been repeated with 51.… Kc8.

Because you have to claim threefold repetition before you make the move 51.…Kc8, producing the same position on the board, this would have been a sensible point for a popup dialog.


Eyestrain - Anyone experiencing eyestrain when playing OTB?

If you are genuinely getting tired "after 10 or more games" because of eyestrain and not just because you are getting old or you play in a stuffy, crowded room where there isn't enough oxygen then I would suggest you have a problem with the lighting.

In some playing areas I have problems when there is not enough light (maybe I'm in a darker corner of the room) or there is not enough contrast between the colours on the board and / or the colours of the pieces. This can give me eyestrain and make me feel tired but it would happen to me much quicker than after 10 games of blitz. If anything for me it would get a bit better after a while as my eyes and brain adjust a bit to the bad lighting conditions.

Note that some people have a problem the other way with over bright fluorescent lighting so I guess for tournament organizers it can be tricky to get it just right.

If I were you I would try and work out which lighting conditions give you the most problems and either sit somewhere where these problems are minimized and maybe if necessary ask the tournament organizer for help on this.


TL;DR: gaining national master level in China is based on gaining competition norms, likely to be in the amateur league.

As you know, national federations can set their own standards for national master titles:

  National chess federations are free to set whatever standards they want for such titles [e.g. National Master], which are not recognized by FIDE. Standards for "Master" titles in different countries vary, but are usually based on criteria such as achieving a certain rating (typically about 2200 Elo), achieving the required number of tournament performances ("norms") at a certain level, or featuring prominently in the country's national championship. In some cases, it may extend to honorary titles awarded to (for example) prominent chess administrators, business patrons or politicians.

Source: wikipedia, emphasis is mine.

In China, you can gain the national master title by playing in tournaments and getting NM norms;

  There are really two tracks for chess players. One is run by the National Chess Association & the National Chess Academy, as well as the associated provincial- and municipal- level chess academies. They award certificates for amateur players, from level 6 (the lowest) to level 1 (the highest), which are followed by the titles of Candidate Association Master Association Master & National Master. Meanwhile, the National Sports Bureau uses a different classification system entirely (recognising instead the ‘Athlete system’), bestowing upon the elite players the titles of Third class (the lowest), Second class and First Class (the highest) Athlete, National Elite and International Elite.

  Chess players gaining the required norms (gaining a certain placing in some designated tournament perhaps, or satisfying the required win rate) can apply for First Class certification. For example, I gained the titles of Association Master and First Class Athlete through competing in various events.

Source: Chess in China: Unveiling the Chinese System on Chess.com, emphasis is mine


Does USCF still pay for the FIDE Master application fee?

Per Chris Bird, the USCF's "FIDE Events Manager", the USCF only pays for GM, IM, WGM, and WIM titles. FM(WFM) and CM(WCM) are the responsibility of the player. The USCF still applies on your behalf, but you pay the fee.

The fees are currently as follows:

Grandmaster/WGM: 330 Euro

International Master/WIM: 165 Euro

FIDE Master/WFM: 70 Euro

Candidate Master/WCM: 50 Euro


What's the best move by white in this game?

The key move is the g3 move.

If the e3 rook is unpinned, black has lot's of troubles
If the b8 knight is under-protected, Qxb8 wins easily

1.g3 achieves both.

 1.g3 Qc7 2.Rxd7 now wins (Qxb8 or Rxe8 coming)

Black should resign.


Why is the Ragozin 4... Bb4 not even considered against 4. Bg5?

I'm not an expert but my guess is black doesn't want white to develop his g1 knight to e2 in a variation he commits his bishop to b4.

For example after 1.d4 d5 2.c4 e6 3.Nc3 Nf6 4.Nf3 Bb4 5.Bg5 h6 6.Bxf6 Qxf6 7.e3, wouldn't you be more comfortable with your f3 knight on e2? You can get that in the other variation!

1.d4 d5 2.c4 e6 3.Nc3 Nf6 4.Bg5 Bb4!? 5.e3 keeps the g1 knight flexible. Now if
5...h6 6.Bxf6 Qxf6 7.Nge2 and white slightly improved his position. That is if you agree the knight is better on e2. There are more than hundred master games played in my database with 4.Bg5 Bb4 so I don't believe it's dubious, just slightly inferior.


What's the best play when you're losing?

Usually when you are decisively down in material, the best option is to make the position as complicated as possible. If you don't create any threats, your opponent doesn't have a chance to go wrong. And if nothing special happens, you are going to lose. So stir it up, create a mess, chaos on the board and suddenly everything is possible again, especially if you're opponent tries to play it super safe and gets low on time.

If your position is just somewhat worse, however, lashing out with some sacrifices often makes it much easier for your opponent to finish you off. So dogged defence against all tactical possibilities is often a better try in such a situation.

Of course if your position is somewhere between worse and lost, it is often hard to decide which way to go. Miss too many chances to mess it up and suddenly you're dead lost. Mess it up to early and suddenly you get messed up. ;-)

One final tip: Try to be ahead on the clock. It is a very common scenario that you defend very well for a long time, and just when the position is equal again, you blunder the game away, because you're low on time.

An example by the current World Champ:
Carlsen-Topalov, 2012:
Incredibly Carlsen just overlooked 20…Nb2, as he said after the game, but he immediately sacrificed a lot more material to get an attack going. Objectively this shouldn't have been enough, but he created enough chaos to eventually confuse Topalov and in the end even win the game.

rnbqkbnr/pppppppp/8/8/8/8/PPPPPPPP/RNBQKBNR w KQkq - 0 1
1. e4 c5 2. Nf3 d6 3. Bb5+ Nd7 4. c3 Ngf6 5. Qe2 a6 6. Ba4 Qc7
7. O-O e5 8. d4 b5 9. Bc2 cxd4 10. cxd4 Be7 11. Nc3 O-O
12. Bg5 h6 13. Bh4 Bb7 14. Rad1 Rac8 15. Bb3 Rfe8 16. dxe5
dxe5 17. Bg3 Bf8 18. h3 Nb6 19. Nh4 Nc4 20. Nf5 Nxb2 21. Bh4
Nxd1 22. Bxf6 Nxc3 23. Qg4 Bxe4 24. Nxh6+ Kh7 25. Bxf7 Qxf7
26. Nxf7 gxf6 27. f4 Bg6 28. Qh4+ Kg7 29. fxe5 Ne4 30. Rxf6
Bc5+ 31. Kh2 Nxf6 32. Qxf6+ Kh7 33. Ng5+ Kh6 34. Ne6 Rxe6
35. Qxe6 Re8 36. Qf6 Be7 37. Qxa6 b4 38. Qc4 Bf8 39. g4 Kh7
40. e6 Bd6+ 41. Kg2 Be7 42. Qc7 Kg8 43. Kg3 Kf8 44. Qf4+ Kg7
45. Qd4+ Kg8 46. h4 Rd8 47. Qc4 Bd3 48. Qc6 Bb1 49. h5 Bxa2
50. Qe4 Kh8 51. h6 Bf6 52. e7 Re8 53. Qf4 Bg7 54. hxg7+ Kxg7
55. g5 Kg8 56. Qf6 1-0


Refutation of the Maróczy Bind, suitable for correspondence chess?

In Beating the Sicilian 3 by Nunn and Gallagher, they claim (emphasis is mine):

  Although the Maroczy Bind is slightly passive for Black, players such as Larsen, Petursson and Velimirović have shown that by patiently waiting for a lapse of concentration from White this line can offer winning chances for Black. The theoretical opinion is that White should maintain a slight advantage, but no one should believe that this is a line in which White cannot lose.

As you know, in a correspondence game lapses of concentration are rarer than in over-the-board.

My generic advice would be to be alert to weaknesses induced by white's last move, and take advantage of that. If you want more specific advice, please post a new question requesting feedback on your middle/endgame play.


The exact origins of chess are not known, but there are several stories about it out there. At the top of my head I can think of at least four different ones that I've heard myself, and after reading your question I suspect that you've heard of one such story about the creation of chess.

One of these, which may or may not be the story you seem to have learnt about, is the one that follows:

A long time ago, a bored king asked one of his underlings to bring him some form of fresh entertainment. The underling thought for a while, and came up with the game of chess. After playing one game, the king was so pleased with what the underling had brought him that he said that the underling could ask for anything he desired as a reward for the invention of the brilliant game.

After contemplating for a while, the underling asked for a grain of rice for the first square of the chess board, two grains of rice for the second square, four grains for the third square, and so on for the remaining squares. The king agreed to the request, and when it was realized that the total amount of grains the underling had asked for was impossible for the kingdom to provide, the king got angry and ordered the execution of his underling for making a fool out of him.

It is important to note, however, that this story has no proven historical validity whatsoever.


Caruana vs Carlsen game 10 (WCC) why not 18...Nxb6?

From a purely positional point of view, 18...Nxb6 would have been a
terrible mistake, as it would have allowed white to then forcefully trade the light squared bishops with the immediate Bg4
move, leaving exposed all the light square weaknesses that black has
created with the d6-e5-f4 setup.

These weaknesses (created holes) would then have been permanently exploited by white's
knight (and queen), in other words, white's minor piece (b6 knight) would have
dominated the game and been virtually untouchable on light squares for the rest of the game.
Notice that next to the knight controlling key light squares from b6,
it's also for example quite feasible for white to re-route the knight
to e4, established centrally (permanently) and constantly eying black's
weak d6 pawn.

And as for black, Carlsen would have simply been left with a bad dark
squared bishop hemmed in by his own structure.
Therefore, Carlsen chose wisely to play Qe8 instead of Nxb6, thus,
preserving his c8 bishop as Bg4 no longer forces a trade thanks to
the well placed knight on d7.

In summary, this is a purely positional decision where black is well
aware that having weakened their light squares, any scenario with the
knight vs dark square bishop would be unfavorable for them, and
arguably,
at that level even objectively lost! Instead having kept both the d7
knight and c8 bishop, black has in fact preserved two pieces that can
provide light square control.

The following situations would have ensued had Carlsen played
18...Nxb6:

18...Nxb6 19.Nxb6 Ra7 20.Bg4

which would have led to positions of the following nature, infested with light square holes:


Sicilian Defence or Caro-Kann also help with Queen's pawn opening

For a more meaningful answer, it'd be a great idea to know what your current skill level is. That being said:
Knowing an opening is not about knowing "what's on the book". If you can't find the correct response when your opponent deviates, then to all practical effects it's as if you didn't know anything the opening, no matter how depth into the mainline you've studied. Mainlines also change over time and from author to author. Study the key strategical ideas of the opening, not concrete variations.
Also consider that at lower levels, it's not really worth studying the opening, since:

The difference between playing well in the opening or not is not that big and there's a lot of time to catch up during the rest of the game if you are worse.
Studying the opening is harder as a beginner because you need to memorize more. GMs can remember hundreds of 20-move deep lines because they only have to remember a few critical points, the rest comes intuitively to them.

When choosing between Hyper-accelerated Dragon and Caro-Kann, I personally prefer the former because as you'll have to know a fair amount of theory for both, you'll better play the opening that puts your opponent into bigger trouble if he messes up. But there are deifnitely arguments for the Caro-Kann and it's hard to tell what suits you best without knowing your skill level or "playing style".
The Queen's Indian is a great opening that can teach you a lot about chess. If you already know about it, there's no reason not to include it in your repertoire


What determines an opening continuation vs an opening varation?

The original distinction was mainly so that chess players have a common vocabulary (for teaching, discussing, kibbitzing) there is the concept of a "main line." Other reasonable continuations are said to be variations. This helped the teachers and the players to learn the opening lines.

Yes, history did play a role in what was considered the main line, and which options were variations. Very often, variations would be given the name of the GM who first played it as a novelty, or the one who plays it very commonly to good results. (Remember, this was in the days when most people learned about games printed chess magazines that showed up several weeks after a game was played.)

These days, thanks to very powerful chess engines and massive databases, the mainline is arguably simply the line that is the most frequent continuation (played by those with high ELOs.)

It is also important to remember that as more games are added to the database, the mainline tends to shift to other moves, especially as refutations are discovered by the opponents.

Hope that helps.


What web-based Content Management System (e.g. Blogger) has the best support for chess content?

I am writing for a Chess Blog (Blogger) from time to time, using KV Chess (former Chess Flash) to generate replayable chess games. Thus, the viewer is embedded as flash code. I did not manage to use PalView, it seemed a bit too complicated and had bugs. Perhaps it is better today? Cheers.


A theoretician is someone who has created a new opening, middlegame and / or endgame variation. You don't have to be a grandmaster to become one, and not all grandmasters are ones.

It may not apply if your variation is not tactical or is useless.

I don't think it matters where a theoretician comes from, as everyone has different chess experience, and whether you are an active tournament player or not.

People who have written about chess theory in general are chess theoreticians.


The French and the Sicilian are almost as different openings as you could get as a response to 1. e4. The French (especially the Advance Variation, which is the most common among amateur play) tends to lead to closed positions, that is, positions clogged up with stable pawn chains where long-term maneuvering and strategy prevail. The Sicilian (as much as there is a "single" Sicilian, seeing as the multitudinous Sicilian systems can range from quiet and defensive [cf. the Sheveningen] to dangerous and aggressive [cf. the Dragon Variation, or the Sveshnikov]) tends to lead to open or semi-open positions, and the tide of play may shift within just a couple of moves owing to tactics.

There's really not much to be said in terms of meaningful, general, and objective "pros" and "cons" of the two opening systems. I would just study very briefly the theory behind the first few moves of each, play several games with them, and decide for yourself which you like to play. They're both super-solid in principle and played all the way up to the GM level.

(If you say you like aggressive play, I tend to think you'd like the Sicilian as such. The French is still among my favorites, however, because as Black you're constantly making White react to your threats of winning small but significant positional or material gains whilst in the opening. As a beginner I found games almost played themselves and if White wasn't keen on defense I would obtain the upper hand.)


What programs (preferably open source) offer play against a computer with fine-grained difficulty-related adjustments?

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

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


What is the best move in this situation?

but by moving pawn to d5 a very dangerous situation will be created that can be irritating until the end of the game.

It can be dangerous to both sides. Positions of these type are generally characterized as the Benoni Defense. They are unbalanced and offer more chances for complicated play. So you may or may not want to avoid such positions depending upon how comfortable you are playing such positions.

  How to defend in such scenarios theoretically?

A good idea for Black is to immediately take on d5, followed by moving the pawn to d6, blockading the pawn on d5. A sample line of development for Black may go like this -

  [FEN ""]

  1. e4 c5 2. d4 e6 3. d5 exd5 4. exd5 d6 5. Nf3 Nf6 6. Nc3 Be7 7. Be2 O-O
  8. O-O Na6 9. Re1 Nc7 10. a4 b6 11. Bc4 a6

The strongest player to consistently play this opening successfully was Bent Larsen. I recommend you take a look at the following games of Larsen to see how Black not only defends this position but also manages to seize the initiative.

Alberic O'Kelly de Galway vs Bent Larsen 0-1 1967

Svetozar Gligoric vs Bent Larsen 1/2-1/2 1969

Wolfgang Unzicker vs Bent Larsen 0-1 1970

Miguel A Quinteros vs Bent Larsen 0-1 1974

Incidentally, even Garry Kasparov once tried this idea in his early days.

Yuri Balashov vs Garry Kasparov 1/2-1/2 1979

  What track could white take to win this game almost surely (if such a thing is even possible)?

It is not known yet whether White can forcibly win in this line. Strong players continue to use this line, although it is not popular at the highest level; but that might simply be because of reasons like taste rather than the objective quality of the position.


An Aggressive Response (for black) against the closed sicilian?

It's difficult to recommend an tactical line against the Closed Sicilian as White is attempting to avoid this sort play by keeping the center relatively closed/semi-open. I wouldn't characterize the play as Black playing purely positionally on the queenside and White "pummeling" black on the kingside - there are a variety of plans for both sides in the resulting middlegames. Black's expansion on one side of the board can be just as effective if not more so than White's attack on the king. An aggressive approach isn't limited to tactical play. I can recommend an approach that may make this concept more evident.

Against 1. e4 c5 2. Nc3, I have played 2...a6 in the past. Black's idea is quite simple - as he knows he's going to be playing on the queenside anyway, he decides to expand there before developing any of his kingside pieces. He usually follows up with moves like b5, Bb7, e6, and d5. This is certainly an aggressive reply to the Closed Sicilian, and can be defined as a positional one as well.


Since you are playing the Queen Gambit, 2.c4 is indeed the most logical way to continue. The main answers, 2...d5 and 2...Nf6, should fit in your repertoire anyway. The alternative is to go for 2.Nf3 first.

Move order finesses

Black's move order bears three subtelties:

You are offered a choice to switch to a French opening with 2.e4. This is probably your opponent's secret hope and since you are a 1.d4 player, you will probably not want to go down that road even though 2.e4 is of course a good move - unless you are fond of playing against the French defense.
After 2.c4, Black can bring the game to original territory with 2...Bb4+. This is a decent line, but not overly dangerous, and you can handle it with general rules (develop, avoid doubled pawns, castle...) if reaching an equal position suits you. Or you can learn a bit of theory about it, although at 700-900 level there are a lot of more important stuff for you to study.
If you want to avoid it altogether, you can start with 2.Nf3. Then 2...d5 3.c4 is back to QGD, with an early Nf3, which might or might not suit you depending on your favorite line of Queen Gambit. Note that 3...Bb4+ remains a decent option for Black.
Dutch players often start with 1...e6 to provoque 2.c4 and reduce their opponent choice: after 1.d4 f5 White often goes 2.g3 or 2.Nf3 and plays c4 only a few moves later, or even plays subvariations like 2.Bg5 or 2.e4, but after 1.d4 e6 2.c4 f5 those options are lost. If you play an early 2.c4 against the Dutch anyway, you won't mind those shenanigans at all, otherwise 2.Nf3 might once again be the solution.

Finally, some Black players also intend 2...b6 or other rare moves you should not be too worried about.

Conclusion

1...e6 is a decent move that plans to reach normal positions while limiting your choice. Those move-order subtelties are interesting when building your repertoire, yet they should not worry you too much until you reach a level around 1800 or so.

The natural alternative for a Queen's Gambit player is between 2.c4 and 2.Nf3; both have pluses and minuses. If it fits your usual way of playing in the QGD, go for 2.Nf3 first before 3.c4 and go for standard, QGD-like development: that avoids 2...Bb4+ tricks and requires less specific work on opening lines that shouldn't be your biggest concern right now.


I think your best bet will be the ECO (or Encyclopedia of Chess Openings)

The following is a complete list of all gambits in the ECO.

Polish Gambit 1. e4 b5
Wing Gambit 1. e4 c5 2. b4
Ware Gambit 1. a4 e5 2. a5 d5 3. e3 f5 4. a6
Birmingham Gambit 1. b4 c5
Schuhler Gambit 1. b4 c6 2. Bb2 a5 3. b5 cxb5 4. e4
Wolferts Gambit 1. b4 e5 2. Bb2 c5
Englund Gambit 1. d4 e5
Budapest Gambit 1. d4 Nf6 2. c4 e5
Benko Gambit 1. d4 Nf6 2. c4 c5 3. d5 b5
Staunton Gambit 1. d4 f5 2. e4
Smith-Morra Gambit 1. e4 c5 2. d4 cxd4 3. c3
Danish Gambit 1. e4 e5 2. d4 exd4 3. c3
Vienna Gambit 1. e4 e5 2. Nc3 Nf6 3. f4
King's Gambit 1. e4 e5 2. f4
Quaade Gambit 1. e4 e5 2. f4 exf4 3. Nf3 g5 4. Nc3
Kieseritsky Gambit 1. e4 e5 2. Nc3 Nf6 3. Bc4 Nxe4 4. Nf3
Rice Gambit 1. e4 e5 2. f4 exf4 3. Nf3 g5 4. h4 g4 5. Ne5 Nf6 6. Bc4 d5 7. exd5 Bd6 8. 0-0
Elephant Gambit 1. e4 e5 2. Nf3 d5
Latvian Gambit 1. e4 e5 2. Nf3 f5
Irish Gambit 1. e4 e5 2. Nf3 Nc6 3. Nxe5?
Halloween Gambit 1. e4 e5 2. Nf3 Nc6 3. Nc3 Nf6 4. Nxe5?!
Blackburne Shilling Gambit 1. e4 e5 2. Nf3 Nc6 3. Bc4 Nd4
Italian Gambit 1. e4 e5 2. Nf3 Nc6 3. Bc4 Bc5 4. d4
Rousseau Gambit 1. e4 e5 2. Nf3 Nc6 3. Bc4 f5
Evans Gambit 1. e4 e5 2. Nf3 Nc6 3. Bc4 Bc5 4. b4
Blackmar–Diemer Gambit 1. d4 d5 2. e4 dxe4 3. Nc3
Queen's Gambit 1. d4 d5 2. c4
Grünfeld Gambit 1. d4 Nf6 2. c4 g6 3. Nc3 d5 4. Bf4 Bg7 5. e3 0-0


This is not an answer, just an explanation why it is difficult to generate a list of unsound openings.

There is the famous quote "Any opening is good enough to be played if its reputation is bad enough" - Tartakower. This tongue-in-cheek quote implies that there are many good ideas in openings which are considered refuted or unsound. More specifically, "If an opening cannot be refuted by concrete variations, it is playable, even when it appears on the verge of catastrophe" - Averbakh. So, for an opening to be considered unsound, it has to fail to some specific tactic.

Lets highlight this with a game. The game below is a mismatch between Karpov (elo 2725) against Miles (elo approx. 2575). Miles plays the eccentric St George variation, 1. e4 a6 and wins! Miles chose this opening because he knew Karpov had an encyclopedic knowledge of all the mainstream openings.

[White "Karpov"]
[Black "Miles"]
[FEN ""]

1. e4 a6 2. d4 b5 3. Nf3 Bb7 4. Bd3 Nf6 5. Qe2 e6 6. a4 c5 7. dxc5 Bxc5 8. Nbd2 b4 9. e5 Nd5 10. Ne4 Be7 11. O-O Nc6 12. Bd2 Qc7 13. c4 bxc3 14. Nxc3 Nxc3 15. Bxc3 Nb4 16. Bxb4 Bxb4 17. Rac1 Qb6 18. Be4 O-O 19. Ng5 h6 20. Bh7+ Kh8 21. Bb1 Be7 22. Ne4 Rac8 23. Qd3 Rxc1 24. Rxc1 Qxb2 25. Re1 Qxe5 26. Qxd7 Bb4 27. Re3 Qd5 28. Qxd5 Bxd5 29. Nc3 Rc8 30. Ne2 g5 31. h4 Kg7 32. hxg5 hxg5 33. Bd3 a5 34. Rg3 Kf6 35. Rg4 Bd6 36. Kf1 Be5 37. Ke1 Rh8 38. f4 gxf4 39. Nxf4 Bc6 40. Ne2 Rh1+ 41. Kd2 Rh2 42. g3 Bf3 43. Rg8 Rg2 44. Ke1 Bxe2 45. Bxe2 Rxg3 46. Ra8 Bc7 0-1

To answer your question, you would need to figure out which openings have a concrete tactical refutation, rather than ones that are offbeat.


Books for beginners who have hard time understanding positions of pieces?

Frankly, what you are asking is not a short-term goal. It really is about leaning chess, and it takes many years. When you ask why you are putting pieces on certain squares, that is called positional chess, and most people only start to absorb that after they are considerably stronger than beginner. There is no one, or even a few, books that will get you there.

What you really need to do is start with tactics books. Those are books that have problems that are forced series of moves leading to advantage. When you do enough of these, you will start to absorb some "pattern recognition". Much of chess is learning many positions, and then applying them so similar positions that arise in your actual games. In addition, these tactics books will help you to start thinking ahead, and in particular, to lose less pieces. At the begging level, most often, it is who loses the least pieces, rather than who wins the most pieces.

There are many, many, books on tactics, but if you are beginning, you want very basic tactics books. Do not shy away from books that are aimed at kids. That is more marketing since it really does not matter if you are a kid or adult, and what matters more is your level of understanding, which is limited to how the pieces move.

Here are some books that I use for teaching kids, actually high school kids, so they are like young adults:

Chess Tactics for Students

Chess Tactics for Kids

How to Beat Your Dad at Chess

Power Chess for Kids: Learn How to Think Ahead and Become One of the Best Players in Your School

Let me add one recommendation that I use often to novices: In the beginning of the game, always ask yourself: "What piece haven't I moved yet?" You want to get all your pieces out since it is hard to win if you are playing with one or two pieces, and he is playing with 4-5.


Rated Tournaments in France - For a Poor French Speaker

As long as you enter FIDE rated tournaments you should be OK. If the arbiter is a FIDE International Arbiter he is required to know English. English is the main FIDE language and according to FIDE Regulations for the Titles of Arbiters -

  4. Requirements for the title of International Arbiter.
  All of the following:
  ...
  4.3 Obligatory knowledge of English language, minimum at conversation level; and of chess terms in other official FIDE
  languages.

Arbiters with just the FA title are not obliged to have good knowledge of English but will need it if they have ambitions to become IAs.

That said, the French are notoriously bad at foreign languages. I went to live and work there after having lived and worked in Germany for some time and the contrast was stark.

My experience going to open a bank account in Munich went something like this -

Me to stereotypical gorgeous, blonde teller: "Entschuldigung Sie. Ich moechte ein Konto oeffnen"
Brunhilde: "Certainly sir. Your passport please? You are working at Digital?"

I tried the same thing only in French at the bank near where I worked on the southern edge of Paris and got a reply in French. With my schoolboy French it was a struggle but she was patient and I just about managed.

For chess tournaments you might be OK but for general life I would strongly recommend you have French lessons while you are there.

Also, if you are the Owen Rees with FIN 343113860 then I would recommend you try and get a proper FIDE ID number before you go. If you are in England (might also work in Wales) then the cheapest / easiest way is to enter a FIDE rated blitz tournament. The ECF doesn't grade blitz and FIDE don't charge federations for rating blitz so you will end up getting a FIN free of federation membership fees.

PS. I'm guessing you already know "j'adoube". The other useful word is "remis" for when you want to offer a draw.


Mismatch between my puzzle rating and game rating on chess.com

Rating method.
On chess.com, my puzzle rating is 700 points higher than my game rating, but my chesstempo puzzle rating is only about 100 points higher than my chess.com game rating. In other words, puzzle rating on chess.com is not comparable with your game rating.
I'd suggest just keep doing 10 (or more) puzzles a day and ignore whatever the gap.


What is the longest possible series of consecutive captures?

Here's an example of 30 successive captures (White's 3rd to Black's 17th). It is the solution (from White's 3rd onwards) of a massacre proof-game found by Gerd Wilts & Norbert Geissler.

[Title "Gerd Wilts & Norbert Geissler.PDB CD-ROM 1998-Version"]
[StartPly "4"]
[fen "rnbqkbnr/pppppppp/8/8/8/8/PPPPPPPP/RNBQKBNR w KQkq - 0 1"]

1.d3 d6 2. Bg5 Bg4 3. Bxe7 Bxe2 4. Bxd6 Bxf1 5. Bxc7 Qxd3 6. Bxb8 Qxc2 7. Bxa7 Rxa7 8. Qxc2 Rxa2 9. Qxh7 Rxb2 10. Qxg8 Rxb1 11. Rxb1 Rxh2 12. Rxb7 Rxh1 13. Rxf7 Rxg1 14. Rxg7 Rxg2 15. Qxf8+ Kxf8 16. Kxf1 Rxf2+ 17. Kxf2 Kxg7


I'm not too familiar with the Java applets that you're looking at, but I recommend that you use JavaScript for this sort of job. This GitHub repository can be used to display and play through your own games (it supports PGN and FEN).

There are many other libraries out there - it's easy for you to change the design of the board and pieces to suit your site's style. You also might want to ask this question on StackOverflow as you might find some more technical advice there.


If you are this Janjic, Slobodan P, I would say that you need to do tactics, tactics, and more tactics. Try to do 50 per day, spending no more than 2 minutes per tactic. At the lower mid-levels, it really comes down to who loses a piece first most of the time.

I want to suggest that as you do the tactics, REALLY try to concentrate as you do them, and do not just play a move that looks good, and hope that you are right....REALLY see it through to the end, and try to visualize what it going on...don't play "hope chess" (I HOPE this works).

I covered this in depth for all rating levels here.


That'd probably be the best way- yes. A typical tournament would be difficult. Probably a blitz time control (something like 3+2) would be best, so games are over quickly. You'd also have to consider what'd happen if a draw occurs- my suggestion is to let the guy who won the game before that stay, or play another game. Also colours have to be decided- id say flipping a coin'd be best (other random selection alternatives are also good).


After 1.Ra2, black's rook and bishop are both stuck; 1...Bb5, defending the rook on a6 while attacking the rook on a2 is no longer effective since 2.cxb5 defends the rook on a2. After this, black's play is completely shut down due to the pin on the bishop, while white is able to make improvements in his position. In particular, white can get a very strong passed pawn on the e-file which black can do nothing about.

This is why the position is so-called strategically winning for white after 1.Ra2. Unlike other types of winning advantages, this one is of quite a long-term nature, and white would still need to show good general understanding and endgame technique to win the game in the end. Let's look at a couple of sample lines:

 [FEN "5k2/p5pp/r7/2pB2p1/b1P5/6P1/4PP1P/R5K1 w - - 0 1"]

 1.Ra2! (1.Ra3? Bb5! {and black escapes the pin in an elegant manner; the bishop on b5 is temporarily immune due to the hanging rook on a3.}) {Paralyzing black's bishop and rook.} 1...g4 {Might as well try to stop white's pawns from advancing.} (1...Bb5?? {This is a terrible blunder now.} 2.cxb5 Rxa2 3.Bxa2 {and white is just a piece up.}) 2.e4 {Push the pawn! A strong and far-advanced passed pawn makes black's movements even more awkward than before.} 2...g5!? {Other defensive tries are available as well, but black wants to keep white down, and doesn't want to allow white's king access into black's position via f4.} 3.e5 h6 4.h4! {Black is given the chance to pick his poison} 4...Kg7 {The most resilient path.} (4...gxh4 5.gxh4 {and white's king is given access to black's camp via f4.} 5...Kg7 6.Kh2 Kf8 7.Kg3 h5 8.Kf4 Kg7 {What now? How does white proceed?} 9.Ke3! {White uses triangulation to put black on the move, thus gaining ground} 9...Kf8 10.Ke4 Kg7 11.Kf4 Kg6 {Black needs to stop white's king, but this allows a tactical trick:}   (11...Kf8 12.e6 Ke7 13.Kg5 {and black is getting squeezed to death.}) 12.Bb7! Rb6 13.Be4+ {and white wins the bishop on a4.}) (4...gxh3  5.f4! {and white creates two strong connected passed pawns. These are unstoppable, and will decide the game.}) 5.Kf1 Kf8 6.Ke1 Kg7 7.Kd2 Kf8 8.Ke3 Kg7 9.h5 {Finishing preparations before liquidation into a winning rook ending by placing king and pawns optimally.} 9...Kf8 10.Bb7! {The way to make progress!} 10...Rb6 11.Rxa4 Rxb7 12.Ra6 {Black's position is starting to crumble, and there is no way to defend all weak points anymore.}

So in conclusion, yes white is winning after 1.Ra2! but the win isn't trivial, and precision is still required afterwards to win the game.


Should a member of a national chess federation register himself separatef for FIN?

The section you quote from the FIDE handbook is very clear. It is the responsibility of the individual national chess federations to register their players. It is not the responsibility of the players. It is the responsibility of the national federations to pay the fee required by FIDE to FIDE.

That said some national federations will have more than one level of national federation membership for individuals. They will charge more for FIDE registered players than for non-registered FIDE players and recoup some or all of the FIDE registration fees that way.

Different federations handle this in different ways and it is nothing to do with FIDE. It might be helpful if you said which national federation you are talking about.

EDIT: Doing some research I see that you are Italian. The Italian chess federation (Federazione Scacchistica Italiana or FSI) has 3 levels of membership, junior (10 Euros), ordinary (25 Euros) and adult (42 Euros). You must be a member of the FSI to play chess in Italy organized by the FSI. Normally you join (and pay) for membership through your chess club. If you want to play in a congress but are not a member of the FSI (through a club or otherwise) then you have to pay the congress your FSI membership fee.

Note that the membership fees I have quoted are old and may be out of date.


I maintain one here that you might like to take a look at to see if it is any use for your purposes:

PGN for ECO descriptions with moves


What is the longest tablebase win that includes draw rules?


What is it like to be a Twitch chess streamer?

First, it would be interesting to know what your goals with the channel will be. If it is to have enough revenue that it can become your job, you will need to offer something that others are not already offering, or do what they are doing a lot better. You need some kind of "angle".

For most chess channels, the angle is that they are Grandmasters, and since I looked you up on FIDE.com for another question previously, I know that you are far from that (I am not trying to be mean there). The other channels that are very popular by weak players also have something in common: Cute girls with good personalities. Alexandra Botez and Gold Dust Tori come to mind. Frankly, Tori is so weak, I could not imagine watching her although I have seen her for a few minutes here or there when a chess.com broadcast I was watching ended, and my channel was "raided" (users that are automatically transferred to another channel). Be prepared to change your approach after some time if you not getting any followers.

I am not saying that you cannot do it, but you will need to find something that makes you very unique. One idea for someone else might be: If you had been about half your age, like 6, it could have been to follow the little boy from novice through to Grandmaster, and grow with him. You are considering trying to stream with a partner. Partners seem to do well here (and on radio and television). A partner allow for more conversation, and for you to bounce things off each other.

Once you have your idea, then there is patience, and promotion. Assuming that you want to make money (if just for fun to have a channel, then all bets are off...just have fun), you would need to understand that it would be a job. You will need to spend many hours streaming for little, or no, money in the beginning until you have a following. Unlike YouTube, Twitch is more about live playing against various opponents, and you discussing what it going on for the audience.

Did I mention that it is a job? (Yes, I know I did.) You would need to take it seriously, and be consistent about your streaming, and that means probably every day, 7 days a week in the beginning. Famous streamers, like Hikaru Nakamura, can take stream as they like since people will show up when they show up (Naka puts his schedule on Twitter, for example).

Promotion. You will need to learn how to promote your channel via social media so people can find you among the multitude of channels. You will need to read books and websites from experts on how to do that. I do not know much about this, but you would need to find out how the system for "raids" works. That might be about building personal relationships, aka partnerships, so established channels are willing to let you take their audience when they are done.

It is a numbers game: You will need follower first, and then maybe they can turn into subscribers. Not all subscriptions cost money since Amazon owns Twitch, and they allow Prime members one free subscription per month. I usually back chess.com or Naka, personally with my Prime membership.

I wish you good luck if you try to do this.

"Tips for becoming a Twitch video game streamer"


I want to give chess tutorials, which software should I use?

Just based on ease of use and aesthetic appeal I'd recommend the free ChessBase Reader which allows you to easily draw arrows on the board and highlight squares. To record your videos you can use free screen capture software such as oCam.


There is now an app called Chesscraft on Google play which allows custom boards and pieces. It plays reasonably well.


What happened to the Chess Cafe website?

Chesscafe announced on June 2 that the number of subscribers was too low to sustain the site and that they would go on a three month hiatus.

Whether they will ever come out of it again is anybody's guess.


Why doesn't 1.fxe4 Nf6 work for black in this puzzle?

Because after Nf6, e5 is a double attack on the d6 bishop and the f6 knight.

The puzzle aside, given that black's dropping the piece anyway, may as well go for something practical, like Nxg3, hxg3, Bxg3+... and take 2 pawns for the piece, with some positional compensation as the king will be misplaced, but objectively white should of course be easily winning.

 [Title "Puzzle"]
 [fen "rnbqk2r/ppp3pp/3b4/3p1p1n/3Pp3/1P2PPP1/P1P1B2P/RNBQK1NR w KQkq - 0 1"]

 1.fxe4 Nf6 (1...fxe4 2.Bxh5+) (1...Nxg3 2.hxg3 Bxg3+) 2.e5


What kind of semi-open file is better for your rook?

Generally when you read/hear something like "to put the rook on a semi-open file" it means a file where the opponent's pawn is on. The reasoning behind this is just piece activity, i.e. to maximize the available squares for the rook and also to attack something (the opponent's pawn on that file).

The only time where it makes sense (on general principles) to put a rook on a semi-open file where your own pawn is on, is if you want to support a passed pawn, typically with the rook from behind the pawn. However this situation would not be referred to as "putting the rook on a semi-open file".

PS: Of course there are situations (like the latter example above), where it could make sense to put the rook on a semi open file where your own pawn is located. However I understood your question as asking about the general principle that rooks are supposed to be good on semi-open files. In that  case it would always be the semi-open file with your opponent's pawn.


Here's a preliminary answer to where such a belief about chess pawns could possibly have come from. In the Japanese variant Shogi, in which an opponent's captured pieces may be placed onto the board as one's own, it is not legal to place down a pawn that gives immediate checkmate. It's still perfectly legal to drop a pawn that gives check though (and to check/mate normally with a pawn), so this a much less severe restriction than what your question asks about. But this is a case in which the pawns are singled out, because any other piece can be dropped to give an immediate checkmate.

Since Shogi and chess are both believed to derive from Chaturanga, perhaps there is indeed some historical variant in which pawns weren't allowed to check at all; but I'm just speculating at the moment.


How should I play after, or refute, the Tennison Gambit?

It looks like your position fell apart pretty early on, a symptom of poor opening theory.  Your King and Queen were exposed to attack within the first few moves, and White ruthlessly exploited that opportunity.

The first move that Stockfish classifies as a blunder (yes, there's more than one) is 5. … h6?? where you attempt to directly attack the advancing knight.  But the knight's threat is not countered by that attack, because it can just continue as planned to threaten your queen, pulling your king out of his home square in an emergency defence.

White then sacrifices his bishop to gain your queen anyway - a net material gain of 3 points if you include his lost knight.  While you then move your knight to attack the White queen, it's too late as he can simply move it away to safety.

The suggested move is 5. … Nc6 which pre-emptively protects your queen, turning the above sequence into a losing proposition for White; the game would then develop along a different line.

This is in general the better way to defend against attacks - protect the threatened squares which the attacking pieces want to move to, rather than where they currently stand.  To do this effectively you must think at least a couple of moves ahead, which takes practice.


I play Benko as black and am a FM. The most trouble I have in quick games is with declined cxb5 a6 b6 line. Without the a line open I just do not have the play that Benko player craves.

Also, I noticed that stronger(IM+) players tend to go for the b6 line, while weaker players either take the pawn on a6 or decline the gambit with something else. For example allowing black to push to b4 has been good for me as black.


How well does Elo rating estimate a player's strength?

It's not clear to me whether you are asking a philosophical or a quantitative question.

My answer to the philosophical question is that the Elo rating is predictive; that is, it is designed to make accurate predictions about the outcomes of chess games. To that extent, it measures strength by estimating the likelihood that a player will win against another player. It does this by using the player's past results, and it does the best it can given that information.

The answer to the quantitative question is that the "expected value" of a game between two players is correlated with the difference in their Elo ratings. For example if player A's Elo rating is 200 higher than that of player B, then player A would be expected to go about 76-24 over the course of a 100-game match.

Note: The question has changed since I answered it, so my answer makes less sense now. The title of the question used to be Does the chess rating represent a player's strength?, and the question was "I notice that somehow, we chess players associate the chess rating with strength. But is it a measure of strength? To what extent?" Please take this answer as a response to that question, not the one it has been changed to.


Is it ethical to spar against an engine when playing correspondence?

Chess.com's site rules have the following to say:

  You can NEVER use chess programs (Chessmaster, Fritz, etc) to analyze current ongoing games unless specifically permitted (such as a computer tournament, etc). The only type of computer assistance allowed is games databases for opening lines in Turn-based Chess and Vote Chess. [...]

So it boils down to the question if playing out positions from a corr game against an engine counts as analyzing.

The answer can only be "yes" because for some possible continuations of your game, the engine provides its best moves. This is clearly an act of analysis.

There will be plenty of time to play against your engine after the game jas finished.


Bf8, while a nice positional move, an excellent idea for a 1200 rated player, is a mistake as Nxe4 wins an important central pawn for no compensation. The Queen can't recapture due to the coming skewer down the long diagonal. See the lines below.
Remember tactics always trump strategy!
[White ""]
[Black ""]
[FEN "1k1rr3/1bpqbp2/ppnp1n1p/6p1/3NP1P1/P3Q1BP/1PP1NP2/2KR1B1R b - - 0 1"]

1...Nxe4 2.Nxc6+
    ( 2.Qxe4 Nxd4 3.Qxd4 Bxh1 )
2...Qxc6 *


Is there an engine which can give a breakdown of its evaluations

Yes. Look at Stockfish 6. You can try it yourself.

EDITED

MG -> Middle Game
EG -> End Game

Most chess engines have a different set of evaluation or algorithm for an endgame. They could use it to model phase transition (e.g.: middle-game to end-game).


Is it common to reverse the rank and file in chess notation?

It's not common (I've never heard of it), and it's certainly not an official notation.  Without further information, I have no idea why the chess master would have accepted the strange notation.  Perhaps he didn't think it worthwhile to argue at the time.
Edit: as Tony Ennis notes, the notation for shogi is quite similar to what you are describing.

The method used in English-language texts to express shogi moves was established by George Hodges in 1976. It is derived from the algebraic notation used for chess, but differs in several respects. It is not used in Japanese-language texts, as it is no more concise than kanji.
A typical move might be notated P-8f. The first letter represents the piece moved: P for Pawn. (There is also L lance, N knight, S silver, G gold, B bishop, R rook, K king, as above.) Promoted pieces are indicated by a + in front of the letter: +P is a tokin (promoted pawn).
[...] For example, the start of a game might look like this:

1. P-7f   2. P-3d
3. P-2f   4. G-3b
5. P-2e   6. Bx8h+
7. Sx8h   8. S-2b

Perhaps that is what the child was thinking of.


Why are you looking for video?  How about looking for a game? Checkout chessgames.com then search for Open Ruy Lopez ECO code to look for games won by black. It will show you how black piece should play against open Ruy Lopez


How deep should I memorize lines of the Sicilian Dragon?

As someone who recently got out of the 1400s, I think it's much more important that you figure out where you want to be developing your pieces and why certain pieces are good in certain places. When I went about memorizing a bunch of moves, I very often (then and now) played people who would do something I'd never read up on.

If instead, you learn some of the reasons and/or general plan for a given opening, I think you'll be better off in the long term.


As a Beginner, is playing a lot of tactics chess (puzzles) a good way to improve?

Solving alot of tactic puzzles is a fantastic way to improve for a beginner.

One of the reasons for my improvement was the constant solving of tactics on chess.com's tactics trainer feature, which basically made me shed my beginner skins, since tactics almost always play a decisive role in the games of beginners.

However, you must also play many normal games, preferably in real life instead of online, and against stronger players, as this will provide you with invaluable experience for the improvement of your game.

You must also familiarize yourself with the strategic features of chess, (backward pawns, space advantages) and the endgame in order to improve. Tactics can only get you so far.


Do "chess engine in the cloud" services exist?

Chessbase has this feature for subscribers. Basically you can analyse your games using their cloud based engine. If you have a powerful machine yourself you can also "rent out" your engine. More details here.

Here is an older article which includes a video explaining how it works and walks you through the process.


Is blocking a check with a check an illegal move?

Yes, it is legal, since your king is no longer being attacked.


Why do titled players always play online (blitz) speed chess?

Good chess players who play online prefer quick games like 10sec + 1 or 1 min because nobody can cheat with a computer engine for such short games.

If a player tries to cheat with a computer, in this type of game, he loses the game on time.

After many quick games, these players can maintain this balance easily. Indeed, they train brain to think very quickly. And those who can think quickly can think slowly. Thus, there is no problem playing slow games after fast games.

Moreover, just for your information, blitz game refers to all chess games where each player has up to 10 minutes for all the moves.


After 1...d6 you could consider playing 2.e4. One of the biggest advantages of 1.Nf3 is it's flexibility and if you are looking for a quiet(ish) game then perhaps a Be2 (Classical) Pirc is your answer.

Against 1...f5 2.d3 has an excellent reputation I believe. (Idea is 2...Nf6 3.e4 and black is advised not to take the gambit pawn).
Worth noting is that 1.Nf3 f5 2.d3 Nc6!? I think the best move is 3.d4! Chess is a funny game.

If you are dead set on a double fianchetto, I guess fianchettoing the kings bishop makes sense first as you get to castle sooner (you can also consider playing b4 instead of b3 after you have castled).


Like all positions in chess, it's incredibly difficult to come up with general terms and common rules for openings. The particulars of each situation must be judged separately.

That being said, the idea that Dzindzichashvili is recommending is a good one - Ne7 stays flexible (and keeps your bishop open) and allows you to quickly strike at white's center with f5 (a crucial pawn break against d5-e5 structures). As you said, this pawn break can be double edged because you are creating a critical hole in your position: e6. So only consider it if there is no chance for white to sink a knight or bishop onto e6.

Now to respond to the line you are suggesting: I would argue that this plan still works in this line as well. Moreover, striking in the center while you are castled and your opponent is not seems principled as well.

[FEN ""]
1. d4 g6 2. c4 Bg7 3. e4 c5 4. d5 d6 5. Nf3 e6 6. h3 exd5 7. cxd5 Ne7 8. Nc3 (8. Bf4?? Bxb2) O-O 9. Bf4 f5!? 10. e5 dxe5 11. Bxe5 Nd7

I agree that you're still in a cramped position, and you obviously have to be careful about the d pawn pushing forward. But let's look at the dynamic positives here as well. The center has blown up and white still needs 2 moves to castle. You have a queenside majority that can instantly start pushing with a6-b5. And you have the ultimate blockader on d7 already setup. So there's no worries there. There are also interesting opportunities for f4 followed by Nf5. These are the types of explosive lines you are signing up for when you allow your center to gain a huge center as early as move 3.

Side note: If you truly want to trade off your light squared bishop, then your best bet is to play 5. Bg4 instead of e6.


A million years ago, a friend  showed a very simple variant: One random  pawn on each side is marked, and if it's captured (by a move that isn't checkmate), the capturing side loses.
The Danish Gambit was popular that night,  but otherwise,  people were flinging pawns around,  planning to win with the variant rule  (I guess you could call it a truly poisoned pawn). I said to my friends that I thought the right strategy was no strategy: Just play chess, and try to win the chess game. You'll lose a few games by chance,  but you'll also win a few.
Was I right or wrong, I won't say.  Maybe you'll try that variant yourself to test both ways of handling it.
I'm a very big fan of the 3 Check variant (so is Karpov). That game messes with your mind. The nitwits who try to win by delivering a third check run out of sacrificial fuel, while playing normally is dangerous, because the variant rule is often just a matter of tactics (that is, some combination that makes one or two checks while sufficiently exposing the king for more).
I gave this castle chess thing some thought,  and I was amused by the different winning conditions.  White is likely to go nuts in search of a short combination to prevent castling, while Black (I think) should play normally but with a view toward O-O-O.
Is there a forced win for White? I doubt it, and after that bit of thought,  I began to favor Black.


Although I know you're on a Mac and I don't know what you've tried so far in detail, this scid-users mailing list thread might be of interest. It suggests to add the exe file in as the command, but without the wine before it. Again, that is for Ubuntu, but maybe it will help.


Can you wait and then perform an en passant capture?

En-passant can only occur immediately after a pawn moves two squares from its starting square, where it could have been captured had it only moved one square.

You cannot wait a move: if you choose not to immediately capture en-passant, you lose the ability to do so next move.


To what extent is the openness/closedness of positions determined by white? By black?

In general White has more freedom of choice due to going first. He can play a move that is slightly suboptimal and still be around equal. But if Black does the same thing, he could quickly find himself in a bad position.

However, it's obviously not always necessary to play dubious moves in order to get the kind of position you want. In general you should play openings that lead to closed/open positions. In the former case 1.d4 makes more sense, and 1.e4 for the latter. As Black, you could meet 1.d4 with something like the Grunfeld if you like open positions, or with the KID if you prefer closed positions. For 1.e4, the French/Caro lead to more closed positions, while the Sicilian has a higher chance of leading to an open position. Of course, these are just examples.


Is the position in this trick question reachable?

Even though the board is upside down, the position is still easily legal.
[FEN ""]
[startply "86"]
[StartFlipped "1"]

1. a4 h5 2. g4 h4 3. Bg2 Rh5 4. gxh5 h3 5. h6 e5 6. Nf3 Bc5 7. Nxe5 hxg2 8. h4 Ne7 9. h5 g5 10. Rh4 Ng6 11. Rf4 g4 12. Rxf7 Qh4 13. e3 Bxe3 14. Ke2 a5 15. f4 Qf2+ 16. Kd3 Nc6 17. b4 b5 18. bxa5 Rxa5 19. Rf8+ Ke7 20. f5 b4 21. f6+ Ke6 22. hxg6 Rc5 23. g7 Rxc2 24. h7 Rxc1 25. Ra3 Rxb1 26. Qc2 Rg1 27. Rc3 Kf5 28. Rc5 Kf4 29. Rd5 Kg3 30. Ke4 Ba6 31. Rxd7 Bf1 32. Rdd8 Qe2 33. Kf5 Bf2 34. Kg6 Kh2 35. Kf7 Kh1 36. Kg8 b3 37. Qc3 Nb4 38. d4 Na2 39. d5 c5 40. Rc8 c4 41. Qd2 c3 42. Qd3 c2 43. Qc3 g3


How is White compensated in these lines of the Milner-Barry gambit?

I am not too excited about this line for white either. Probably there is a reason that it is not played much.

What resources does he have?

As in most French, white has more space, two good bishops (vs one good for black) and if black castles short there are always ideas with attacking the king because most of black's forces are concentrated on the queen side.

Also, because you took on c5, white does not have to worry anymore about black taking on d4, making it easier to play particularly for a more positional player.

As for future plans, black most likely wants to play a5 to prevent white playing b4, Be3, a3, c4... Black's pieces are currently placed ok, but there is not much they can do from where they are. Likely sooner or later black wants to attack in the center with f6 or even d4.

After black's a5, the square b5 gets weak and white can target it developing for instance with a4, Na3, Nb5, perhaps later putting  a knight on d4.

And if black castles short kingside attacks are always an option.


What are electronic chessboards used for?

I assume you are referring to DGT-style electronic boards.
I think the main purpose of those boards is to broadcast chessgames - e. g. on a beamer in the playing venue or on the internet. It is also useful (if it doesn't fail) for blitz games or, more generally, in any game situation where none of the players write down their moves any more if you need to comprehend the course of the game as an arbiter.
I don't see lots of uses outside a tournament context. The GM you referred to may have used it to record what he did on the board. Some people feel better analyzing on a "real" board rather than using the chessbase broadcast or some screen-capture method.
The only reason I could see to buy one as a person that does not intend to do the things mentioned above would be if you were too lazy to write down what you play in practise games or if you want to practise blitz games (although even here I could think of much cheaper alternatives if I look at the prices they sell at).


What is the strongest chess engine for blitz time controls?

As @FranS points out, the CCRL 40/4 list I linked to fits the bill pretty well. I was digging around on a lot of sites and must have thought that this one was showing results for 40 moves in 4 hours. I'm leaving the question up rather than deleting it in case someone comes along with the same question later.

Also, by following some links on the question that @Salvador Dali linked to I learned that there was an event called The World Computer Speed Chess Championship that seems to have died after 2011.


Best solution
If there is nothing wrong with my rather spaghettoid script (admittedly, a big if) then there is no complete solution. The best my computer finds is two cycles.
It finds essentially three such solutions plus a few minor variations. Interestingly, the split is always 3-13.
[FEN "1Q6/3R4/NB2P3/1P3P2/2P3P1/1N1P3P/P4KB1/R7 w - - 0 1"]

.
[FEN "R7/BP6/2PK4/6R1/2N3BP/1N1P2P1/P3PP2/Q7 w - - 0 1"]

.
[FEN "6R1/6BP/1N4P1/P4P2/BP2P1NK/2PP4/7Q/3R4 w - - 0 1"]

Strategy / computer implementation
From the assumptions follow a handful of constraints that enable an exhaustive search.

There are no more than 4 chains of Ps. That is because Ps can only attack other Ps or Rs or Ns and each separate chain has a P at the base that is not available to be attacked by another P. Each chain is capped by a R or N.
The major pieces each have a rank to themselves. That is because there is at least a P on their file, so they must spend their attack on that file. The Q, in particular, must also have her diagonals to herself.
The Q must be attacked by a N.
At least 1 chain of Ps must be capped off by a N. There are at least two Ps on the same rank and their respective chains cannot be both capped by Rs because then 1 chain would have to cross the private rank of the other chains R.

Using these constraints makes the code rather verbose and ugly but keeps the number of candidates below a million or so.
Relaxing the rules
If we lift the one pawn per file rule it becomes untractable for my computer program, but we can solve manually
[FEN "6R1/1R6/1BP3BN/3P2P1/2P2P2/1P4P1/P1N2K/Q7 w - - 0 1"]

Last word: The i files
We can actually achieve a full solution with no doubled pawns by ever so slightly bending the rules. All we need to do is rip out the f file but relax we are putting it right back: as the new i file. Job done:


If a Woman Grandmaster (WGM) transitions to a man, does he retain the WGM title?

FIDE has not ruled on that possibility yet.  No national federation is known to have ruled on that yet.

A related case is going to the US Supreme court that might influence how others do eventually rule should such an event ever actually happen.


+8 -11 =19 means: Won 8, lost 11 and drew 19


Why can't I use my stockfish engine with python chess?

In the error log you've pasted you can see it's a permission error, which can occur for files that behave as "executables" if you will (think any form of program, e.g. scripts, compiled files etc), but that have not been given the rights by the os to do so. One way to fix it, go to the folder containing the engine file and open a terminal to run the following command which will render your file as executable to the os:

chmod +x stockfish_10_x64

Alternatively, right click, go to properties, permissions and select "allow executing file as program".
After this (by either method) you should be able to load and run the engine within the python-chess library.


Can the pawn take the rook in this position?

Pawns are a pretty complex piece. They can make the following types of moves:

Move one square forward, if that square is not occupied by any other piece.
Move two square forward on their first move, if neither of those squares is occupied by any other piece
Capture a piece diagonally in front of it
Capture an enemy pawn "en passant".
When they get to the 8th rank, they can "promote" to a Queen, Rook, Knight or Bishop

So, in the position you're showing, your pawn can capture either the enemy rook or the knight, but not the pawn right in front of it.


Why does NN + MCTS & AB + handwritten eval dominate engine chess?

Speed

Neural networks operate much more slowly than handcrafted evaluation functions. In the TCEC Superfinal, Leela Chess Zero, running on two GPUs each with dedicated tensor cores, is able to search around 60 thousand positions per second. By contrast, Stockfish, on a single core on my PC, searches over 2 million positions per second.

While modern engines have a huge selection of techniques to cut off unnecessary branches, alpha-beta tree search is still very much a brute force technique, requiring vast numbers of positions to be searched to determine good moves.

MCTS, by contrast, is far more selective, and only expands its search tree towards the most promising moves, which allows it to make the most of the more limited number of nodes that can be searched.

Worst-case behaviour

One of the key requirements of the evaluation function for an engine based around alpha-beta search is that it must have good worst-case behaviour. This is because any large error in evaluation, however rare, can easily be propagated to the root and lead to a horrendously incorrect move being played.

By nature of their complexity, neural networks are prone to overfitting and can only be as good as the data used to train them. For example, in match 80 of the TCEC Season 14 Superfinal, on move 47 Lc0 was apparently unfazed by Stockfish's extra queen, evaluating the position as a cool +0.77, while Stockfish (and most other engines) sported an evaluation of +8.31. A popular explanation for this is that Lc0 may not have had a significant number of games with multiple queens on the board in its training set.

Neural networks, therefore, have poor worst-case behaviour, and hence are likely to perform poorly with alpha beta search. MCTS, by contrast, allows an incorrect score assigned to one position to be offset by averaging it out with reasonable scores assigned to positions nearby in the search.

Quiescence

All strong alpha-beta engines use a technique called quiescence search, a restricted form of alpha-beta search applied at leaf nodes, in acknowledgement that their handcrafted evaluation functions only work well in "quiet" positions, where there are no pending captures or checks.

For example, immediately after the first half of a queen exchange, a handcrafted evaluation function might tell you that the side which just had their queen taken is completely lost, whereas a neural network may be able to understand that the queen will be recaptured soon.

This makes handcrafted evaluation functions similarly unsuitable for MCTS due to absence of quiescence search, resulting in the handcrafted functions performing poorly much of the time (although Komodo 12 MCTS gets around this restriction by using short alpha-beta searches anyway, to get quiescent positions and hence allow its handcrafted evaluation to return a reasonable score)


Two questions about how the en passant capture works

En passant can only be played when the enemy pawn moves over your pawn's capture square during it's first move (moving 2 squares); so the answer to both condition 1 and 2 is no.

It is not possible for a pawn to en passant twice in a row.

My understanding is in early chess pawns could only move one space at a time, so when the 2 move rules was added they also added en passant to counterbalance the fact that you might lose a chance at capturing your opponent's pawn since he could now move over your capture square.

So, in essence, because after capturing en passant it is no longer possible for an enemy pawn to pass over your capture square, it is no longer possible for your pawn to capture en passant.

The official FIDE rules, article 1 section 3.7d states:

  A pawn attacking a square crossed by an opponent’s pawn which
  has advanced two squares in one move from its original square may
  capture this opponent’s pawn as though the latter had been moved only
  one square. This capture is only legal on the move following this
  advance and is called an ‘en passant’ capture.


Which classic chess books are in the public domain?

The International Chess Congress, St. Petersburg, 1909 is a classic by World Champion Emanuel Lasker was written in 1910 and is in the public domain.

[EDIT] ISBN: 1888690097, can be viewed online or downloaded in PDF at http://archive.org/details/internationalche00lask


How should black react if white plays "defensively"?

Being aggressive and taking the center are two different things.

Regarding being aggressive, if White is making defensive moves, it's OK for Black to do the same as long as each move has a strong purpose.  For example, Black might fix flaws in his position by repositioning poorly placed pieces or securing his King.  If he instead chooses to attack and there are exploitable flaws, his attack can he blunted.

For example, if Black's King is exposed yet he attacked, White would have the opportunity to gain a tempo by moving an endangered piece and checking the King.  This is like giving White two moves in a row on the area of the board where the attack is happening.  Or, worse, White could play a Zwischenzug.  Both these things things make calculation difficult.  Better to first move the King to a safer square.

Taking the center, which is less aggressive, is rarely a bad idea, as long as one can hold onto the real estate.  Taking the center is good preparation for attack and gives one the flexibility in choosing how the attack should be conducted.


Unit Testing a chess board representation

When reading your question, my gut reaction is that your scope is too complicated for unit testing.  I recommend a quick read through the free e-book Unit Testing Succinctly.  However, I have no experience writing chess code (maybe your paradigms are different) - although I do software for a living.

A unit test should be very simple and test a function that does 1 single thing.  Then you can combine the functions with some reasonable expectation that they will work.  For example, I would expect a unit test for each piece to determine if a particular move is legal.  A unit test for each piece to determine if it is putting the king in check.  A test for each piece to determine where it is attacking, etc.

Testing a position seems like a very complicated unit test and would be much harder to do thoroughly.  Instead write smaller tests against smaller functions and then know that those individually work - evaluating a position is just a matter of iterating over the simple functions.

If you want to test a position for a good (not forced) move, I think unit test's will artificially limit the long term development and strength of your chess engine... a binary result of a unit test will force your engine to make the same move every time.

I'd also look at adding unit tests for 'most direct' path to a mate with known endgames.  I'd look to add unit tests for traversing through known openings as well.  Mid game unit tests will be much harder - maybe plugging in a position and evaluating that the engine produces a usable result (which is a binary response).

For the question of evaluating a set of positions for your engine, you may do far better putting this question on https://stackoverflow.com/ with the "chess" tag.


Mathematical formula to get how broad opening repertoire is

I don't believe your approach works because you're counting every position as an opening repertiore what you're actually measuring is the degree to which they play openings where theory has prescribed a large number of moves.  For example, a Ruy Lopez player might play the first 15 and 20 moves to reach the end of book play.  In contrast, someone who plays the Trompowsky or another unusual opening might be out of book after six moves.  Therefore, I would define "opening" differently.  For example, you could use ECO standard positions as a starting point for defining a person's opening.  I believe Eric Schiller also has an list of chess openings.


Is it better to reply to 1.Nf3 with ...d5 or ...b5?

After 1.Nf3 the most popular answer is 1…Nf6, which is a hundred times more common than 1…b5. 1…d5 is the second most popular choice, still fifty times more likely to appear on the board than 1…b5.

Now the difference between 1…Nf6 and 1…d5 is mostly one of compatibility with the rest of your opening repertoire. 1…Nf6 is more common because the indian defences are more popular than the 1…d5 against 1.d4.

But 1…b5 is decidedly offbeat. The reason is that it doesn't immediately fight for control of the central squares. The importance of the central squares is explained in the answers to this question:
Why is the centre of the board considered important in chess?

Still, 1…b5 isn't a mistake. It has the ideas of developing the bishop to b7, making c4 impossible and maybe annoy a Nc3 in the future. If black can consolidate, the additional space on the queenside might make a difference.

The main problem from a theoretical standpoint is probably that it is rather slow: 1.Nf3 b5 2.e4 Bb7 3.Bxb5 Bxe4 4.Nc3 Bb7 5.O-O and white has quite a significant development lead.


Pawn confrontations: capture, push past, or leave the tension?

This is too complex to have straight principles. Of course there are some patterns that you are going to recognize during your improvement and there are also easy things. I'm going to mention a few at the end of this post. First of all, let me refer to positions cited by you.

Position #1
Key is calculating, always, and this is great example. First thing you should do is asking yourself: what can I do? Can I not react, keep the tension? The answer is 'No.'. Your e4 pawn is hanging. You can't play d3 because you'd lose your knight then. Bd3? Too facticious obviously. So now comes the question: e5 or exd5? Well, after exd5 - Nxd5 c3 is hanging, f4 is hanging, I don't really like it. There are moves like Ba3 but somehow I don't like playing such moves. To sum up, after a moment of fast calculation, I'd choose e5.

Position #2
You mentioned all the possibilities. Why do people choose 3. Nc3 frequently? It's most aggressive, probably giving best chances. But it's also most complicated, definitely. Nd2 is also quite nice, if I recall correctly it's Micheal Adams' favourite choice. If you want a draw just exchange and develop your pieces. Positions after 3. exd5 are mostly drawish. e5 are for closed-positions-lovers. You should know what fits your play-style. If you are willing to be better at french, I suggest you nice video series on this topic by Rustam Kasimdzhanov, I think it's chessbases' stuff.

Position #3
It's also all theory. You can play exchange variation or keep tension. That's also something you should fit to your play-style. One thing is for sure, never play 4. c5 here. That's losing advantage on the spot. Simple 4. ... - b6 and you are not white anymore after few moves.

Position #4
It's calculation...again. As you correctly mentioned: playing f4 is pointless. It's giving up a pawn for literally free. So again, two choices here. If we don't take, what do we play? f5 is hanging, so let's defend it. We can play g6 and create additional holes or move our Nd7 to f8 or b6 to discover your Bc8. Once we jump anywhere (same after g6) white is going to play e5. Black is too squeezed. His pieces are passive, his Queen is on h5 doing nothing. It's hard to find a continuation. And again, after few moments we are sure we should capture on e4. So ... - fxe4 is a move here, then best to exchange Knights since when you are the passive one, you should look for exchanges.

Now few easy positions with patterns or principles.

[fen "4k3/pp3ppp/3p4/4p3/3PP3/8/PP3PPP/4K3 w - - 0 1"]

You rather don't want to exd4 because your d6 pawn is weak then. (assuming there are more pieces of course.

[fen "8/1p6/2p5/1PPp4/3P4/8/8/8 w - - 0 1"]

You rather don't cxb5 because then your d5-pawn and b7-pawn are weak. (assumption like above)

Those 2 above were pretty easy, now something more difficult (but not too difficult) and illustrative.

[fen "8/p5pp/1p1bk3/PPp4P/2P1K1P1/8/4N3/8 w - - 0 1"]

As white you should play a6 here. Whole point is in the future your plan will be something like that: Nc1-b3-a5-c6. Taking advantage of impossible bxa5 because of b6. Of course this must be calculated (again!) and well prepared. This is just and example of pattern. Unfortunately, this is probably impossible to paste you 1000 examples here. This comes along with experience and you will notice that for yourself. Those were just few examples, hope you get my point. Good luck!


Against 1.c4. This will allow white to exchange their c-pawn for black d-pawn and later gain a tempo. 2. cxd5 Qxd5 3.Nc3, or 2...Nf6 at some point will be followed with e4 with tempo. All in all, white can take control of the center.
According to lichess' database 1.c4 d5 is very rarely played.
However, the move is probably not losing; stockfish gives it: 0.6. The significance of this advantage varies a lot depending on the player's strength.


Here are some zugzwang positions which have been shown in answers to earlier threads:

4k3/8/3P1P/8/8/3p1p2/8/4K3 w - - 0 1

First to move loses (posted by GloriaVictis at this question on symmetrical zugzwangs).

8/8/8/3pK3/2kP4/8/8/8 w - - 0 1

The "trebuchet" (posted by Evargalo in the same thread).

3k4/3P4/4K3/8/8/8/8/8 w - - 0 1

Posted by Simon Louchart in this thread.

Here is a Q v RPP zugzwang: White to move can't win, but Black to move loses:

[Title "KQkrpp position from John Beasley's collection of zugzwang positions"]
[StartFlipped "0"]
[fen "kr6/1pK5/pQ6/8/8/8/8/8 b - - 0 1"]

1... Rc8 2. Kxc8 a5 3. Qxb7#

Seeing as a KBP v K position has been posted in another answer, here's an example of such a position which really is a zugzwang: White to move can't win, but Black to move loses:

[Title "KBPk position from John Beasley's collection of zugzwang positions"]
[StartFlipped "0"]
[fen "kB6/8/1PK5/8/8/8/8/8 b - - 0 1"]

1... Kxb8 2. b7 Ka7 3. Kc7 Ka6 4. b8=Q Ka5 5. Qb3 Ka6 6. Qa4#


Struggling to find a good opening with black? (Fide Elo 1950)

You say you've looked at most of the major defenses to 1. e4 except the two best, 1... e5 and 1... c5.

It sounds like what you're looking for is just about any Sicilian variation. Most of them require a lot of theory to not get killed on a regular basis but it sounds like you're fine with that. The Taimanov or Paulsen would be a good starting point because 2... e6 avoids White's 3. Bb5 tries that can be so annoying after 2... d6 or 2... Nc6.

If you have an aversion to the Sicilian for some reason, I wouldn't be so quick to reject the French or Caro-Kann. There is plenty of active play in each of them if you choose the right variations.


Convert ChessBase format to PGN on Linux

Scidb can do it.

Here is how

Open the CBH database.
When it is opened, go to the Database tab.
Right-click on the rectangle of the CBH database and click on Export.
Choose PGN or any other format.
Enter the filename and click on Save.

The only drawback of Scidb for now is that it cannot unarchive .cbv file by now.

I made to tool to unarchive .cbv files. I believe it will be integrated into scidb in the future.


How does White justify giving up the bishop in ECO C36 - King's gambit declined

I think Jonathan Garber's comment about trying to gain time against the Black queen after 6...Qxd5 7.Nc3 accurately describes what one motivation for 6.Bxd5 can be, though I also think that Black happens to have nothing to worry about in that regard. While she is temporarily behind in development, she shouldn't have any troubles completing her development, while letting the extra pawn on f4 go and simply enjoying her bishop pair on an open board. Being fuzzy about it, I'd say that all in all, everything evens out here, and we have a quite level game on our hands after 6.Bxd5.

I think another way to look at the reasons for 6.Bxd5 is in "what else?" terms. According to my database, the only more popular move in this position (though it is about 3 times more popular) is the sensible 6.O-O, but after the most popular response 6...c6, Black will be happy to camp out with a nice healthy piece on d5, until White sees fit to exchange it somehow. (This could be the same response to other moves as well, e.g. 6.Nc3 c6 and sit tight.) Perusing through some high-level games, it seems that White not infrequently ends up playing a later Bxd5 anyway (though certainly not all the time).

So, one possible takeaway: the position is already quite level after 5...Nxd5, and the immediate 6.Bxd5 is as good an option as White really has to try and create a favorable dynamic imbalance (of the sort Jonathan Garber mentions), even though IMHO Black has nothing to fear in this instance. One reason the King's Gambit isn't terribly popular at the highest levels - the occasional Nakamura game notwithstanding - is that Black does have some fairly reliable methods of defusing White's more ambitious prospects if she knows what she's doing, and this line for Black seems like an instance of that.

As an example of how things can go well for White, here's Magnus Carlsen using this line (by transposition) against Wang Yue. Around the time of 11.Qe2, we have the sort of balance described above, where White has a lead in development and more central space and control, but Black has safely castled and has nice bishops in an open setting. Then Wang Yue somewhat perplexingly engineers a bishop trade himself, and plays rather passively the rest of the way, letting Carlsen do what he does and make maximum use of the remaining White pluses:

[FEN ""]
[Event "Bazna Kings 4th"]
[Site "Medias"]
[Date "2010.06.17"]
[Round "4"]
[White "Carlsen, Magnus"]
[Black "Wang Yue"]
[Result "1-0"]
[WhiteElo "2813"]
[BlackElo "2752"]
[ECO "C36"]

1.e4 e5 2.f4 d5 3.exd5 exf4 4.Nf3 Nf6 5.Bc4 Nxd5 6.O-O Be7 7.Bxd5 Qxd5 8.Nc3 Qd8
9.d4 O-O
10.Bxf4 Bf5 11.Qe2 $10 Bd6 $6
12.Bxd6 Qxd6 13.Nb5 Qd8 14.c4 a6 15.Nc3 Nd7 16.Rad1 Bg6 17.Qf2 Re8 18.h3 Rc8
19.Rfe1 Rxe1+ 20.Rxe1 c6 21.d5 Nf6 22.Qd4 cxd5 23.Nxd5 Nxd5 24.cxd5 Qd6 25.Ne5 Re8
26.Re3 Rd8 27.Nc4 Qf6 28.Re5 h6 29.d6 Bf5 30.Nb6 Be6
31.d7 Kh8 32.a4 g6 33.Qc3 Kg7 34.a5 h5 35.h4 Rxd7
36.Nxd7 Bxd7 37.Qd4 Bc6 38.b4 Bb5 39.Kh2 Ba4 40.Rd5 Bc6 41.Qxf6+ Kxf6
42. Rc5 Ke6 43.Kg3 f6 44.Kf2 Bd5 45.g3 g5 46.g4 hxg4 47.h5 Be4
48.Rc7 f5 49.h6 f4 50.h7 g3+ 51.Ke1 f3 52.h8=Q f2+ 53.Ke2 Bd3+ 54.Ke3 1-0