Is this a kind of training software that actually exists? This may seem like a silly thing to want to do, but I have been thinking lately that some kind of training software that does the following might be helpful to me:

Show me a board position, and let me study it for a bit.
I click a button or something, and the position is no longer displayed.
After some (hopefully configurable) period of time, it displays the next position in the move sequence.
I have to identify the move that was made that got from the first position to the second.

The reason this is something I'm interested in doing is in the interest of time management during tournaments.  If I want to get up and leave the board during a game (to use the restroom, get something to drink, just stretch my legs and walk around a bit - whatever), I never do it on my opponent's time - because if I return to the board and they've made a move, I can never tell what move they actually made without trying to peek at their scoresheet, or asking (which seems rude...).  So I end up only ever getting up and leaving the board when I'm on move, with my own clock running, and this seems sub-optimal.  This is something I've never been good at (being able to identify what move has been made if I don't actually see it happen), and I'd like to be better at it.

Is there anything available that's intended for building this skill?

I'm not going to answer your question directly, but will attempt to address the root cause of your problem. The skill of seeing which move your opponent played in your absence is something that you should acquire naturally over time. In the beginning I also struggled with this, but after a few months I found that I can easily pick up which move my opponent played. This is probably due to:

Becoming familiar with popular moves in your opening choices.
Anticipating opponent responses. It goes without saying that you should have an expectation of how your opponent will respond whenever you make a move, which cuts down on the number of potential moves you need to actively remember.
An improved ability to keep track of all the pieces on the board - in the beginning, 32 pieces feel like a lot, but over time your mind start to keep track of the individual pieces.
Improvement over time at spotting common tactical themes/motifs/patterns. Doing chess puzzles will probably help in this department.

In normal playing conditions you should never ask your opponent for anything, but you have a right to look at his scoresheet at any time, so don't feel uncomfortable when taking a peek if you are unsure about which move he played. When it is your move (as it would be in this situation) it is OK to even take his scoresheet physically and study it. I see this happening all the time.

A quick note on your habit of leaving the table when it's your move - I believe it is now against FIDE rules to leave the board while it is your turn - you may want to make sure about whether that rule applies to your local competition to avoid any unpleasantness.


How many moves out do the static board evaluations use? These days many online chess websites offer a board evaluation rating, often a bar, sometimes a number, sometimes both, as is the case here (see two red circles):

Black will take a pawn soon, so the evaluation is -0.9 pawns to white.  Note that there are two components to the score.  First, there's a raw score due to some sort of piece scoring system.  Second, there's a positional evaluation scoring element that considers future moves and future pieces that might be taken.  Seems clear, right?

Not exactly.  Consider, near the end of the game, a pawn can get converted into a queen.  Using the most popular piece-ranking systems, a pawn=1 can switch to a queen=~9 via this process.  Therefore, if a player is a pawn ahead, and players play well, eventually, on average, one can expect that this might get promoted to a queen.  Perhaps if you averaged it would be 3 (wild guess) considering that most other pieces can't get promoted.  Anyway, one can see that the second term in the ranking scoring system has a look-ahead variability in that lopsidedness will increase in positive feedback fashion such that a 1 is much higher the further an engine looks ahead.  This positive feedback would exist even without promotions.

My question is just how many moves these engine look ahead in ranking static boards.

Note that there are two components to the score. First, there's a raw
  score due to some sort of piece scoring system. Second, there's a
  positional evaluation scoring element that considers future moves and
  future pieces that might be taken.

This is wrong. The "piece scoring system" is part of the positional evaluation that is considered at the end of possible lines. It doesn't matter what the pieces are now, it matters what they will be in the future. Therefore the -0.9 is equal to the score after the best move black can currently do, 2...dxe4. It's also equal to the score after the best move white can answer to that, moves other than 3.d3 apparently scored worse. This is called the "minimax algorithm".

At the time static evaluation is done, it looks only at that exact position and doesn't look ahead more moves. The looking ahead part is done by then.

Pawns get different scores depending on where they are. I think that most engines compute some score that says how "endgameish" a given position is, and if it's more endgameish then a pawn gets a bigger bonus for being far advanced, but that's actually guesswork on my part.


Which 20th century grandmster had the highest draw percentage in their career? The title says it all. I am looking to learn and adopt a play style which does not necessarily win, but is typified as being incredibly difficult to actually win against,  hence why I wish to know who had the most draws.

World Champion Tigran Petrosian was known to be almost impossible to beat.  He's your man.  Study his games and legacy.

Per Wikipedia, he lost 1 out of 129 Olympiad games.  Olympiads are top-notch tournaments and the score is over 20 years of play.  He's not a flash in the pan.

In his 8 Euroteams competitions (held every three years from 1957 to 1983) he lost -0- out of 52 games.  His team won the competition every time.

Then I started poking around in chessgames.com and I started looking at win/loss/draw ratios.

I made a list of all world champions since Botvinnik, including the weird ones where FIDE lost control.

The three players with the best win:loss ratio (in order): Kasparov (6.62), Fischer (4.87), and Petrosian (4.38). Kasparov dominates. (Only Karpov and Botvinnik are in the same class as these three.)  I expected Kasparov and Fischer to be in this list. I was surprised that Petrosian was there, to be honest. But we see that he was very much able to score the win. He's about like Fischer in this regard.

The three players with the best win:draw ratio, in order: Fischer (1.7), Botvinnik (1.22), and Kasparov (1.02). Fischer dominates. No other players are in their class.  I attribute this to an uncompromising aggressive desire to win.  No half measures. Petrosian was not afflicted with this mentality.  If it did not fit, he did not force it.

The three players with the best draw:loss ratio, in order: Petrosian (6.74), Kasparov (6.52), and Kramnik (6.25).  Spassky and Karpov trail. No one else is close.  This means that even if you had an advantage over one of these players, you'd have to work like mad to score the full point.

The three players with the best win+draw:loss ratio, in order: Kasparov (13.14), Petrosian (11.13), and Kramnik (9.73).  Each is dominant over the next. Karpov and Spassky follow Kramnik closely.  This reflects upon the difficulty of scoring the full point.   An opponent would twice as likely to nick a full point off Carlsen than Petrosian.  Ouch. (I think this is a statistical fluke due to Carslen's age...but it makes a good story.)

Finally, while I did not list it, Petrosian has one of the lower win:draw ratios.  He was more than willing to accept a draw if he could not see how to secure the win.  Other players with a similar win:draw ratio do not possess Petrosian's compensating win:loss ratio, however.

This rather defines his style, I think.  You can see here a player who will defeat you if you aren't careful. He is patient and takes few chances. If you get ahead of him, he'll likely wear you down, into a draw.  And if you err, he'll crush you.

edit - fun facts for the world champions...

In the 4 ratios I looked at (w:l, w:d, d:l, and w+d:l)...

Kasparov is the only player who made the top-3 in all 4 ratios.
Petrosian is the only player who made the top-3 of 3 ratios.
Fischer and Kramnik both have two top-3 honors, but also each have a bottom-3 honor.
Botvinnik is the only player with a single top-3 honor.
Topolov and Carlsen each have three bottom-3 honors.
Carlsen excepted, the three champions from the weird FIDE years (Ponomariov, Kasimdzhanov, and Topalov) have the lowest W+D:L ratios.  There is a marked just in score difference between them and the next lowest scored player (Smyslov).  Find the clue.


Defeating 1600 rated chess computer on chess.com I just defeated a 1601 rated computer in under 3 minutes. Normally, it is a lot more difficult to defeat players having rating even 1500+.

I want to understand how is that possible. Was it a computer that was wrongly rated at 1600+ or did I really outperform it?

[FEN "7k/8/6p1/8/7P/8/3r4/4q2K w - - 0 1"]

It never looked like a computer playing at 1600! What really could have happened?

I want to understand, how is that possible - was it a computer that
  was wrongly rated at 1600+? or did I just outperform it really?

Neither.

You don't understand rating systems. There is no absolute rating system in which to say the computer was or wasn't playing at 1600 strength. All rating systems are relative. They measure the relative performance of the players results in that system. There is no judgement of the quality of the moves.

If the computer rating system is accurate then if you set the computer program to play against the same computer program (with you feeding in the alternate moves) on another computer and one is set to play like 1600 and the other like 1700 then over a large number of games the 1700 computer should score a certain percentage against the 1600 computer.


How to improve from ~1200? I am not new to the game of Chess. I have been (casually) playing it for over a decade, and I would like to get better at it.

I know the basic rules of the game very well, I understand basic tactics (forks, pins, skewers, zugzwang), good bishops vs. bad bishops, center advantage, etc, and I believe my core principles are pretty good.

However, I do not have any actual theory memorized, and I believe I miss out on some positions.

I would like to understand the game better and get to 1500 by the end of the year. I am willing to put in time and effort. What resources/books would you recommend?

@Arka Mukherjee, I find most players under 2100 weak tactically, so at 1200, you are certainly weaker than you understand you are. I do not say that to be mean, but just as a very logical person, who has been a reasonably strong player for over 30 years.

At your level, memorizing theory is mostly a waste of time. In 40 years of playing, I cannot tell you how many weaker players I have seen that carry around an arm full of opening books, but they never progress. You do not need to memorize openings when your opponent is not going to play them because he has not memorized them. You need to understand opening pawn structures. Chess Opening Essentials: The Complete Series (Volumes 1 - 4) is a very basic way to start this.

This is, of course, on a different level, but I recently read something about Kramnik training young prodigies, and one of them played an opening he saw a higher-rated GM play, and he imitated the play by rote, but soon went astray. He did not understand, at least on the much higher level he was at. Understanding is the key.

Beyond that, tactics are the most important thing you can do. Most chess games between weak players are decided by who drops the last piece, and these books would help you win more material, and thus, win more games.

I recommend starting with "1001 Brilliant Ways to Checkmate", and then "1001 Winning Chess Sacrifices and Combinations" (21st Century Editions) by Reinfeld.

I recommend doing 50 per day, spending no more than two minutes per move on each problem. In pencil, write down next to the problem how easy you found it on a scale of 1-5 because you will do these books multiple times. That immersion method has worked very well for me. I took a friend, who was about 38 at the time, from 1000 to 1850 on ICC in three months following this method.


How to calculate the FIDE Percentage Expectancy Table Section 8 of the FIDE Rating Regulations provides the following table

I understand that dp=800 and dp=-800 are arbitary caps at the top and bottom of the table.

However, in relation to the other scores, what's the formula for the conversion of p into dp, and vice-versa?

As noted in the comments, the regular Elo formula almost works but does not quite work. Does anyone know what the formula is for the adjustment made in the tails?

It's basically just table 8.1a with the columns switched. E.g. the entry in table 8.1b with rating difference 92-98 and expected score (for the higher rated player) of .63, corresponds with the entry (.63, 95) in table 8.1a.

That table is based on the expected score formula mentioned here:

  If Player A has a rating of RA and Player B a rating of RB, the exact formula (using the logistic curve) for the expected score of Player A is

  EA = 1 / (1 + 10 (RB - RA) / 400)

but it's also possible to directly generate table 8.1b from this formula. For example, a rating difference of 92 points (in A's favor) leads to EA = 0.6294.

The inverse formula, calculating the rating difference which corresponds to a certain expected score, is RB - RA = 400 log10(1 / EA - 1).


Better opening than Ruy Lopez Exchange? I currently use the Ruy Lopez Exchange (1.e4 e5 2.Nf3 Nc6 3.Bb5 a6 4.Bxc6). Is there a simpler and/or better opening to use instead?

"Simpler" is somewhat subjective. You could argue that learning a system like the King's Indian Attack is simpler because you can play it irrespective of what black plays, while playing the Ruy Lopez Exchange requires your opponent to cooperate to some extent as at any move there are perfectly fine alternatives.

The Ruy Lopez Exchange variation is not the most popular line at the highest level, but there is nothing wrong with it. If you are happy with it and like the positions you get out of it, there is no reason to change.

If you are not happy with it, you could analyze yourself, what kind of positions you like. Perhaps compare positions you get out of different openings (e.g. around move 15) and see which you like best.


Beat the Polish defence I was playing a game against a FIDE master which started with the Polish defence, Spassky gambit: 1. d4 b5 2. e4 Bb7 3. Bxb5 f5

[White "Bad_Bishop"]

[FEN ""]
1. d4 b5 2. e4 Bb7 3. Bxb5 f5

What are the main plans and variations?

I have the book "1.d4 Volume 2" by Grandmaster Boris Avrukh in front of me. Not the line you're looking at but Avrukh says 3.Bxb5 Bxe4 4.Nf3 Nf6 5.0-0 e6 6. c4 Be7 7.Nc3 Bb7 is perfectly playable for Black.

Avrukh's mainline vs the Polish defence is 1. d4 b5 2. e4 Bb7 3. Bd3 (solidifying the centre and aiming to prove the centre pawns are better than the wing pawns.) Nf6 (3...a6 4.Nf3 transposes to the St. George defense) 4. Nd2 e6 5. Ngf3 a6 6. 0-0 c5 7.dc Bxc5 8. e5 Nd5 9. Ne4 Be7 10. a4 b4 11.Nfd2! (heading for c4 and and freeing the Queen on the d1-h5 diagonal) ... and eventually += on move 18. The main plan for White is to play with pieces in the free space in the centre and possibly aim to attack on the Kingside or fill the holes left behind in Black's pawn structure. For more details buy the book.


Why I can not improve in chess & why I can not see the things? Why is it that I can not improve in chess? When I lose a game, I feel very angry. I am always trying to improve so I played a lot, but I can not see any improvement. Please suggest me something.

Everything is a matter of dedication, but with the correct techniques.

You should not feel angry, but glad! Your opponent just gave you the opportunity to figure out what are your weakness, so you can fix it! :D

Also, you are probably playing a lot of fast games. DON'T DO THAT!

Chess is a game of thinking. You need time for that. That's why chess is naturally a slow-paced game. Everything is so fast nowadays... Slow down a bit. :)

Prefer to play slow games (30min at least - 1h+ ideal). Let your speed build up naturally, at your own pace.

Also, I strongly recommend that you study the basics deeply. Most players (specially beginners) have a lot of "holes" in their knowledge (and don't know that), but they think they have a "playing style".

Stop trying to "win fast" using traps and studying lots of openings and variations. That's remembering, not playing.

There are a few concepts that you MUST know by heart to play good chess in every move:

1) Find all possible:

Checks
Captures
Threats (Pins, forks, etc.).

And I mean ALL of them. Don't consider if it's good or bad yet. That's how the Masters find such great tactics and sacrifices! It's the CCT technique.

2) Find the Least Active Piece (the one that dominates the least squares), and think about what is the best square to put it, where it will have it's Maximum Activity (controls the most squares possible). That's the LAP=>MA technique. Piece Activity is the most important of all concepts, because all the others come from it.

3) Now you reorder the moves you found from the most forced (aggressive) on the top of the list, going down to the least forced (passive) move. That's the Candidate Moves List technique.

4) To be better organized and don't get lost doing that, look at one piece at a time, in descendant order of power/importance: King, Queen, Rooks, Bishops, Knights, Pawns.

5) If you are in the opening, keep in mind it's main goals: Develop the pieces, Control the Center, Protect the King. That's the DCP technique.

6) In the endgame, pawns are everything. Remember that each of them is a potential Queen! Don't try to chase the opponent's King, because in an open board, with few pieces to help, he can escape easily, and you will waste time.

Important! - Do all of that to your opponent first!! (like if it's his turn again). Only after that, you calculate for your own side. That's a great secret, hard to find anywhere, and is the best way to avoid those embarrassing blunders.

The deeper (more moves ahead) you can calculate, the better. About 3 is good, 5 is great (you will hardly need more than that) and 7 is about Master level.

Plus: When you are going to study a game (the ones you lost are the most important), a book, or a video, use all those techniques combined with the "Guess the move":

In a book, cover the moves list an try to figure out the next move.
In a video, pause it after every move, and try to find the next move.

Try as hard as you can, on every single move, always for both sides.

When you think you found the best move, write it down on a paper and include WHY you think it's the best move.

Only then you can see what was the next move made.

Did you guess it right? Great! Go to the next one.

Did you guess it wrong? Don't go further before you find out and completely understand why your move wasn't the best.

You will see that all those techniques combined are enough to bring you (at least) close to the Master level!

I spent 15+ years to find that out... Oh if I had someone to teach me just that when I was beginning... Only now I'm getting at 2000's.

You won't need to remember lots of variants of lots of openings. They will just start to feel right.

Try all those techniques in every move, since the very first one.

Try them everyday to solve chess tactics problems! You will see how things will suddenly start to make sense! And you will hardly make blunders if you use them correctly.

Of course, there is no "chess pill of success", but you won't get much closer than that... :) You have to take your time to learn how to use all of that properly.

I hope that helps. Forgive my bad english... I'm from Brazil.


Free tablebase generator software? I'd like to play a bit with fairy tablebases (Vaclav Kotesovec published quite a few) and am far too lazy to program them anew, especially as I wouldn't wonder if there is free code floating around, and I just would have to find where the PARAMETER N=8 statement hides. (BTW, the results can be quite interesting: as I suspected anyway, Q vs R is drawn on a very large board, and with the right size even a mutual zugzwang exists.)
Still, I never was lucky googling. Do you have any resources? (GitHub, chess programming BBS, maybe even scientific papers)

I never was lucky googling

No need to google. All you needed to do was search on this site and you could have come up with this answer which amongst other things says:

Ronald de Man (syzygy developer) has published software for generating these tablebases (up to 6 man) on Github


What is the difference between an inaccuracy, a mistake and a blunder on lichess? I used lichess to analyse some of my games (lichess.org -> tools -> import game). It puts my bad moves (and those of my opponent) in one of three categories; "inaccuracy", "mistake" and "blunder". I guessed from the names (and the positions) that an inaccuracy is better than a blunder, but I wondered what the definitions were.

Blunder: 300 centipawns

Mistake: 100 centipawns

Inaccuracy: 50 centipawns

This is sourced from http://en.lichess.org/qa/75/how-are-these-determined-blunder-mistake-and-inaccuracy

It is the first thing that appears when you google "lichess inaccuracy mistake blunder".


Is it possible to force checkmate with King, Knight, and Bishop vs. King? If a King, Knight, and Bishop are pitted against the opposing King, is it possible to force checkmate? I find it very hard to do, enough so that I'm not sure whether there's a clean method.

Yes, mate can be forced in 33 moves from nearly any position, according to Wikipedia.

See the standard "w" maneuver cited in that article.


Bird's Opening and the Dutch Defense A naturally positional class-C player (c. Elo 1500), I have learned in recent years to push my f-pawn two squares early in the opening, to force myself to play tactical chess.  The King's Gambit (which I had never tried until three years ago) surprises me in how often it unnerves my black opponent:  I have won more games with it than I should have thought possible, mostly because of my opponents' blunders.  Even against the Sicilian, 3. f4 has proved an interesting move though it lacks the sheer psychological impact of the King's Gambit.  With the black men, I have been trying the Dutch Defense 1. d4 f5.  I have been losing, but I have been trying it, and eventually I hope to figure the Dutch out.

My question therefore is this.  If f4and f5 are such interesting moves in the opening, then why should Bird's Opening 1. f4 be so much less common than the Dutch Defense 1... f5?  Is it only because the King's Gambit is better than Bird's, or is there some other reason?

To be clear, my question today is not whether pushing the f-pawn two spaces is wise or fundamentally sound.  Believe me, having tried it over and over during recent years, I have learned a lot of ways to lose by pushing that pawn!  My question regards rather, among aggressive players who will push the f-pawn, why black tends to push the pawn earlier than white does.  Given the increased risk black runs by pushing the f-pawn at the disadvantage of a tempo, one would think that white, not black, would be the leading f-pusher -- whereas 365chess.com has 1. f4 in 0.6 percent of all games, compared against 1... f5 in 3.6 percent of games that have begun 1. d4.

In light of the relative popularity of the Dutch, why should Bird's Opening be relatively so uncommon?

Good question, and to understand the differences, we have to first discuss "reversed" openings.

The most common example of a reversed opening is the King's Indian Attack (1. Nf3 2. g3 3. Bg2 4. O-O 5. d3).  Compare that to the King's Indian Defense (1... Nf6 2... g6 3... Bg7 4... O-O 5... d6).  The only major difference between the following two positions is which "side" has the move:

King's Indian Defense

[title "White to move"]
[fen "rnbq1rk1/ppp1ppbp/3p1np1/8/2PPP3/2N2N2/PP3PPP/R1BQKB1R w - - 0 1"]

King's Indian Attack:

[title "White to move"]
[fen "r1bqkb1r/pp3ppp/2n2n2/2ppp3/8/3P1NP1/PPP1PPBP/RNBQ1RK1 w - - 0 1"]

In the second diagram, white has a full extra tempo over black in the first diagram.  However, this extra tempo is not so useful.  Depending on what white does, black will adopt various formations to nullify white's extra move.  In the first diagram, black can wait to see how white develops before committing.

In fact, Bobby Fischer said (somewhat tongue in cheek) that in the following symmetrical position, black has the edge:

[title "White to move"]
[fen "rnbq1rk1/ppp1ppbp/3p1np1/8/8/3P1NP1/PPP1PPBP/RNBQ1RK1 w - - 0 1"]

1. ( 1. c4 e5) e4  c5

If white plays 6. e4, then black will respond with 6... c5, but if white plays 6. c4, then black will play 6... e5, in both cases leading to a fighting game.

So with that lengthy introduction, now we can look at the Bird.  To begin, after 1. f4, black can immediately strike with From's Gambit: 1... e5! when black scores incredibly well (49.5% from the link in EdDean's answer).  White's best might be to transpose to a King's Gambit with 2. e4.

Furthermore, black will again have an edge that white usually does not have in the Dutch - the ability to see how white develops and then react accordingly.  White can certainly play a quiet system like 1. f4 2. Nf3 3. e3 4. d4 5. c3 and play with that color complex, but if white does that, he is squandering his first move advantage and can claim only equality.

If white tries an enterprising system like the Leningrad Dutch (1. f4 2. g3 3. Nf3 4. Bg2 5. O-O 6. d3 with the plan to play e4), then black will have the opportunity to strike back with h7-h5-h4 when white will have to defend against a fairly vicious attack.  In the Dutch there are various ways to avoid this plan from white although they are beyond the scope of this question.

Hopefully this gives you a bit of an introduction to not only the differences between the Bird and the Dutch, but also how to evaluate reversed openings.


What should be the next move for Black? Both sides have had equal points untill now. If the Black knight is moved, then  White can move their knight with discovered check. What should  Black do?
[FEN ""]
[StartPly "11"]

1. e4 e5 2. Nf3 d6 3. d4 Nf6 4. dxe5 dxe5 5. Nxe5 Nxe4 6. Qe2

Based off your position; I let the engine play it out and the below was the "best" output I received. This is just an old fashioned slog for the centre. A lot of trading going on.
[Event "Analysis Request"]
[Site "?"]
[Date "2020.09.09"]
[Round "?"]
[White "Unknown"]
[Black "Unknown"]
[Result "*"]
[SetUp "1"]
[FEN "rnbqkb1r/ppp2ppp/8/4N3/4n3/8/PPP2PPP/RNBQKB1R w KQkq - 0 1"]
[PlyCount "10"]

1. Qe2 Qd5 2. Nd3 Be7 3. f3 Nd6 4. Nf4 Qc6 5. Nd3 O-O *

1. Qe2 Ngf6 2. Nd2 Qd5 3. Nxe4 Nxe4 4. Qb5+ c6 5. Qxd5 cxd5

Based of the board;
Blacks castled to safety, the white Queen is in danger of (Re8 ... Bh4+). White feels "under developed" and has less control of the board.


The best chess websites or apps to play on I am a beginner. Is there any place where I can play online and improve my game? I know of sites like Chess.com but unfortunately you have to pay for them. My parents won't allow me to spend money on it. What are the best free chess websites or apps?

The best completely free website I know of is Lichess. Personally, I use Chess.com. It's free to play on, and many of the features it has can be used by anyone. However, to gain full access to the website (e.g. the video library), you do need to pay for a membership. It is relatively inexpensive though—$100 per year, which is equivalent to $8.33 per month. (Other membership options are even cheaper.)

Many people still prefer Lichess, and it does have the advantage that absolutely everything is free. Ultimately, I think the best way to answer your question is to try out everything:

Proprietary (to gain full access, you need to pay):

https://www.chess.com
https://chess24.com
https://www.chessclub.com

Open source (completely free, and run by volunteers):

https://lichess.org

Note that even the chess websites that offer paid subscriptions often come with a money-back guarantee. If you're organised enough to cancel your subscriptions, then you can pretty much trial everything before coming to a decision.


White's non-e4 opening, do they all need a solid understanding of 1.d4 first? I'm talking about the two major alternatives apart from e4/d4, ie c4 and Nf3. It seems to me that a lot of the lines will transpose to a d4 type. Sometimes white plays d4 and transpose. Sometimes black plays d5 and white goes into a Queen's pawn defense with an extra tempo.

So is it possible to learn any of these openings without a solid understanding of 1.d4 first? I feel insecure that black can always trick me into a Queen's pawn opening.

Also a related question. Is it possible to learn the English 1.c4 without first playing Sicilian as black myself?

There are c4/Nf3 lines where White never plays d4 (such as the reverse Dragon or the King's Indian Attack). They are solid but not top-tier openings. Additionally, they do not feature much diversity of pawn structures, which can impede learning.

Specifically after 1. c4 e5, this is less relevant because the game does not usually return to 1. d4 structures.

My advice to a player that is trying to improve would be to play 1. d4 for a while first, or learn enough of the d4 transpositions that there is no fear of being tricked.

If not trying to improve, then almost anything is a reasonable choice.


Black castling long in the Sicilian When and why does Black castle long in the Sicilian? What kind of strategies should both sides adopt in such games? What kinds of games does it give rise to, i.e. positional or tactical? Which players are well known practitioners of such as Black?

Black castling long in the Sicilian is a rare thing indeed. I can think of a few reasons:

Black castling long is very rare in chess in general, only a few slow going openings (Caro-Kann, Scandinavian) feature it in general. It takes longer to prepare for long castling than for short castling, the king is less safe on c8 than on g8, white moves first so it's even riskier for black than for white.
In the Sicilian, white generally gets quick development and an attack so it should be even more dangerous.
Black has moved 1...c5, making the queenside less fit as a home for a king.
Besides, one of the ideas of the Sicilian is to play along that c-file with a rook on c8, doesn't combine well with castling long.

So in general black only goes queenside if white has a full-force attack on the kingside and the center, and there is basically nowhere else to go.

I can think of one exception right now in the c3-Sicilian, where the queens are off the board and black can castle with check:

[FEN ""]

1.e4 c5 2.c3 d5 3.exd5 Qxd5 4.d4 Nc6 5.Nf3 Bg4
6.Na3 e5!? 7.dxe5 Qxd1+ 8.Kxd1 O-O-O+ *

and lines similar to that.


Where can I play this 2v2 chess variant online? There is this chess variant in India and we call it 'Supply'. Its a 2 vs 2 game with 2 boards and 2 players of a team take alternate colors. The standard rules of chess apply, but with one twist. If your team member captures a piece on his board he can give it to you and since you are your teammate's opponent's color, you can introduce that piece on your board and continue playing, while introducing the piece on your board. There are few rules like no checking and no pawn promotion by putting it on the last rank. The first team to get checkmated loses. This mod of chess is really fun. I don't know if people play this outside India, and what it is called. I would like to play it online with my friends. Do you know any place online where I can play this variant?

In America, we call this variant Bughouse, although most players allow place mate. Most online chess playing sites do have this variant.  Lichess, chess.com, chessclub, freechess, and chess.net.
Another variant is crazyhouse.  Here when you capture a piece, it changes color and becomes one of your drop pieces.  Unfortunately this also allow place mate.


Why aren't there any women super Grandmasters (GMs)? In chess you don't need to be physically strong. Well, you need some kind of endurance, but is it the real reason why there aren't any super strong women GMs?

Yes, I know about Hou Yifan and Judit Polgar, but they aren't even close to being world champion.

I understand that there are a lot more men chess players than women, but how many women are in top 100? Even the disproportionate number of players can't explain this.

What is the reason then? Can we deduce that men are smarter than women or shall we conclude that there are more geniuses among men than geniuses among women?

I don't know a lot about chess or even gender differences in cognition, but I do know enough that chess involves certain aspects of cognition and that there are gender differences in cognitive ability. For your question, about the number of super GMs, the average abilities of men and women is more or less irrelevant. You need to look at the tails of abilities. Again, there are differences in the tails. Men are better (both on average and at the extremes) for some abilities and worse at others. Women tend to excel at verbal and social cognition while men excel at spatial aspects of cognition.

In addition to cognitive differences, men and women react differently to competition and my guess is you cannot be a super GM without a strong competitive side. There are also social and cultural differences between men and women. Even if there were equal numbers of recreational players, that doesn't mean there would be equal numbers of competitive players (or similar rates of individuals willing to dedicate their lives to chess).

The popularity of competitive chess may well stem from its emphasis on male dominated traits (i.e., spatial cognition) and its lack of emphasis on verbal and social cognition.

The source of these gender differences (i.e., nature/nurture or intrinsic/learned) does not really matter, as the end result is that there are differences. As to whether these differences can explain the lack of women super GMs, it is not clear. That said, given there are measurable differences in cognitive abilities, reaction to competition, and social and cultural influences, it seems wrong to conclude that the lack of women super GMS means that men are smarter than women or that there are more male geniuses.


Why, or how, can GMs make mistakes in opening books? In the following position, McDonald states that 14. d4! is the move that gives a large advantage to White.

r1bqr1k1/2p2pp1/pbn4p/1p1np3/P7/1BPP1N2/1P3PPP/R1BQRNK1 w - - 0 14

However, 14. axb5 wins not one but two pawns and without any unnecessary complications, such as opening the center up and allowing Black some freedom.

After using Stockfish to verify this, I wonder why (or how) GMs write mistakes in opening books, when they have engines to double-check. Why does this happen?

In such a case, I would consider an editing blunder. Can you give the moves that lead to that  position ? I would not be surprised, for instance, if the comment was written with respect to the same line where ...Bb7 is played instead of ...Bb6.

r2qr1k1/1bp2pp1/p1n4p/1pbnp3/P7/1BPP1N2/1P3PPP/R1BQRNK1 w - - 0 14

In this position 14.axb5 leads to nothing but exchanges, but 14.d4 indeed looks very strong: 14...exd4 loses to 15.Rxe8 Qxe8 16.Bxd5, and if the Bc5 retreats then 15.dxe5 grabs a pawn with a discovered attack on the Nd5. White wins (at least) a good central pawn.

Writing a book is a long process: you study a variation, finally the variation won't enter the book because you found an improvement earlier, you analyse a position, then another one that's very similar but not identical, you check one with the software but maybe you forgot the check the second, then you have to send a draft of a chapter to your editor, meanwhile you are writing the next chapter, and the editor wants you to reduce the material by one fourth, so you come back to your text, cut this and rephrase that, and at the end you have a few days (at most!) to proof-read the final draft before it goes to print... Even for the most organized writers, errors will happen at some point.

Even without a computer, there is no doubt McDonald would find 14.axb5!+- in less than twenty seconds if given the diagram in the question. That's why I think this error is due to the production process rather than the chess process. It could be anything, from a comment meant for another section being copied-pasted to the wrong spot, to the typo Bb6/Bb7, or the wrong draft section sent to print.

It is sure pretty annoying for you reader when you meet such a mistake – at least, it keeps your 'scientific skeptical awareness' in alert when reading. But the author will be the most pissed off by such an accident: not only the message he wanted to pass about a variation is spoiled, moreover his name is associated to a 'ridiculous' assessment.


What's the maximum number of moves that can result in a threefold repetition from an arbitrary position? Assume that the fifty-move rule does not require a player to claim a draw. Instead, the game is automatically declared a draw if no pawns have been moved and no pieces have been captured in the last 50 moves.

Hence, we don't need to maintain the entire game history to detect threefold repetitions. We only need to maintain a history of the last 100 positions. Out of these 100 positions, half of them are white-to-play and the other half are black-to-play. Hence, only 50 of these 100 positions could possibly be the same as the current position.

Now, out of these 50 candidate positions if each position is repeated twice then we only have 25 distinct positions which could possibly be the same as the current position. Hence, the upper bound on the maximum number of moves that could result in a threefold repetition is 25.

However, it's very unlikely (dare I say impossible?) that there's a position with 25 possible moves that would lead to a threefold repetition. I believe that the actual number is much smaller. We may never know the exact number. Nevertheless, can you prove that the upper bound is lower than 25?

NB. I'm asking this question because I'm developing a neural network that plays chess. Hence, I'd like to reduce the size of the input to the neural network as much as possible. Providing a history of 25 positions to the neural network is a lot.

Twelve moves is the maximum:

[FEN "5K1k/6p1/6pp/8/8/8/b7/Q7 w - - 0 1"]

1. Qxa2 Kh7 2. Qa3 Kh8 3. Qa4 Kh7 4. Qa5 Kh8 5. Qa6 Kh7 6. Qa7 Kh8 7. Qg1 Kh7 8. Qf1 Kh8 9. Qe1 Kh7 10. Qd1 Kh8 11. Qc1 Kh7 12. Qb1 Kh8 13. Qa2 Kh7 14. Qa3 Kh8 15. Qa4 Kh7 16. Qa5 Kh8 17. Qa6 Kh7 18. Qa7 Kh8 19. Qg1 Kh7 20. Qf1 Kh8 21. Qe1 Kh7 22. Qd1 Kh8 23. Qc1 Kh7 24. Qb2 Kh8 25. Qa3 Kh7 26. Qa4 Kh8 27. Qa5 Kh7 28. Qa6 Kh8 29. Qa7 Kh7 30. Qg1 Kh8 31. Qf1 Kh7 32. Qe1 Kh8 33. Qd1 Kh7 34. Qc1 Kh8 35. Qb1 Kh7 36. Qa2 Kh8 37. Qa3 Kh7 38. Qa4 Kh8 39. Qa5 Kh7 40. Qa6 Kh8 41. Qa7 Kh7 42. Qg1 Kh8 43. Qf1 Kh7 44. Qe1 Kh8 45. Qd1 Kh7 46. Qc1 Kh8 47. Qb1 Kh7 48. Qa1 Kh8

Moving the Queen to a2, a3, a4, a5, a6, a7, b1, c1, d1, e1, f1 or g1 all lead to threefold repetition.

As @RemcoGerlich explained the Black pieces have to reset for the positions to be the same.  Black is resetting after every other move (on moves 2, 4, ..., 48) in the example above which is the quickest possible.

Thirteen moves would require the Black pieces to reset at least 26 times however Black can reset at most 25 times in 50 moves.


How to Create Positional Theory I've been playing Kraton Chess, which is basically standard chess except there are 96 different possible starting positions that are similar to the standard starting position. All the rules of standard chess are in Kraton Chess including castling with no additional rules.

I have some interest in studying the possible starting positions in order to play quicker and stronger in my openings. I might memorize some potential moves to play, but I'm mostly interested in understanding the elements of the position. Understanding elements of a position would help me understand what I should be thinking about in my openings. For example, a pawn having no support in the starting position might be an element worth remembering. Does anyone have any advice on how to go about this? Also, if I do memorize moves, should I just memorize whatever an engine suggests?

It's not critical to know what Kraton Chess is to answer the question. But if you're interested, Kraton Chess has two main differences to Chess960. The king must start on the E file, and rooks can't start on the D or F files. (This improves castling.) The possible starting positions must have an equal chance of being chosen for each game, and the game must start right after the position is chosen. Kraton Chess is more thoroughly described in this post, although it is long: https://www.reddit.com/r/chessvariants/comments/f20xgw/kraton_chess/.

This seems to just be a version of Chess960 restricted to certain openings to make castling more like "normal". Thus the positional considerations should be identical to regular chess, and regular chess principles (e.g. control the centre, develop your pieces early, gain space, etc.) should apply with equal force here.

What does change is the pattern recognition, to an extent. Particularly for how to handle the minor pieces, the intuition built up by playing normal chess (put knights on f3/c3, bishop to c4/b5, etc.) is gone.

Undefended pawn in the starting position: Obviously this can be a target for early attacks. Watch out for these, and be alert for tactics that could win/lose you a pawn.

Generalised opening principles: The usual chess opening ideas of controlling the centre, developing minor pieces and getting the king to safety should still apply. However, some of those ideas are specific cases of principles applicable to other chess types and variants:

Mobility. In the overwhelming majority of chess variants, mobility is the key principle, I would say even the most important one. Development is about improving your pieces' mobility. Controlling the centre is also about getting more mobility. Having more material means you have more pieces, and hence more options (more mobility!) than your opponent. Aim always to improve your pieces' mobility.
Speed. In developing your pieces, you want to do so as quickly as possible. Finishing development first means you can start to increase the pressure on your opponent before they have the chance to react.
Piece coordination. This is less focused on in regular chess than in other chesses like xiangqi and shogi. It ties in with the previous two points: you want to get your pieces to their optimal locations quickly (speed) such that they don't get in each others' way, and hopefully work together to control some squares (mobility).

So for the opening phase of Kratos chess, for instance, you'd want to look at your position and identify some kind of deployment of forces that, as a whole, brings your army to life. Try to identify the pieces that seem the hardest to develop, and work out a plan to get them active; don't neglect it and focus too much on your other pieces to the point where they get in the way of the neglected piece.

And of course plans must change with enemy contact. At every move, try to make sure your moves give you the flexibility to satisfactorily develop the rest of your pieces in as many ways as possible, so that you can adapt your plans if necessary.


How long does it take for Elo rating to reflect changes in player's strength? Suppose a player with ELO rating X has improved (for simplicity, without playing in tournaments) and she is now actually playing at the level X+N. How many games will it typically take for her rating to reach the level X+N, depending on N? Is there a quantitative research into that?

The way FIDE rating (and rating change) is calculated is described in FIDE Rating Regulations effective from 1 July 2017. For an already rated player the calculations for working out the rating change are given in section 8.5.

From here it can be seen that how fast a rating changes for a given performance depende on the "k factor". This is defined in 8.56:

  8.56 K is the development coefficient.
  K = 40 for a player new to the rating list until he has completed events with at least 30 games.
  K = 20 as long as a player's rating remains under 2400.
  K = 10 once a player's published rating has reached 2400 and remains at that level subsequently, even if the rating drops below 2400.
  K = 40 for all players until their 18th birthday, as long as their rating remains under 2300.
  If the number of games (n) for a player on any list for a rating period multiplied by K (as defined above) exceeds 700, then K shall be the largest whole number such that K x n does not exceed 700.

Here are the relevant sections of 8.5 describing the calculations:

  8.5 Determining the rating change for a rated player

  8.51 For each game played against a rated player, determine the difference in rating between the player and his opponent, D.

  ...

  8.54 A difference in rating of more than 400 points shall be counted for rating purposes as though it were a difference of 400 points.

  8.55 (a) Use table 8.1(b) to determine the player’s score probability PD
  (b) ΔR = score – PD. For each game, the score is 1, 0.5 or 0.
  (c) ΣΔR x K = the Rating Change for a given tournament, or Rating period.

As to your question:

  How many games will it typically take for her rating to reach the
  level X+N, depending on N?

Table 8.1(b) is non-linear so as well as depending on the k factor the number of games also depends on N in a non linear fashion. So, you will have to perform separate calculations for different values of N.

Here is an example for N=100. How many games would a player require to draw against players on average 100 points higher to raise the rating by 100 points?

In that case, according to table 8.1(b), PD = 0.36. So, ΔR = 0.14 and the number of games required for a 100 point rating gain = 100 / 0.14 / k.

For k = 10 number of games = 72
For k = 20 number of games = 36
For k = 40 number of games = 18


Is there a way to get a FIDE ID without playing in FIDE rated events? Is there a way to obtain FIDE ID, also known as FID, without actually participating in FIDE rated events? I don't mean obtaining a FIDE rating, just the ID.

The reason why I am asking is simple: this summer I am going to Pardubice Czech Open and I would like to invite my father with me. I myself have a FIDE ID, but my father doesn't, and he lives in an area where FIDE rated events don't happen often so it is quite unlikely he can get FIDE id through playing in a tournament before Czech Open.

The issue is that according to the Czech Open rules foreign players must possess a FIDE ID to take part in their rated tournaments, so it might be so that my father won't be able to participate.

He has a national rating around 2150.

Is there a way to just get registered by FIDE and get an ID or something like that? Maybe through FIDE online arena? I have created an account for him on there and entered all the personal information, but it appears that to have his official online rating calculated we need to pay 25 euros fee. Not a big deal, but I am reluctant to do so without having some assurance that this will result into assigning FIDE ID for him.

See the licensing regulations from FIDE Handbook, particularly 1.13.3.

  1.1   Registration is the procedure of entering a player’s personal details into the FIDE players’ database.

  1.2   A player registered to FIDE acquires a FIDE ID number (FIN).

  ...

  1.13  Registration can be made in 4 different ways:

  1.13.1     National Rating Officers can register new players associated with their own National Federation and ‘FIDE flag players’.
  1.13.2     The FIDE Rating Administrator may register new players under special circumstances only, in FIDE events. In this case the
  Chief Arbiter and the Organiser are responsible for providing correct
  players' data. FIDE events are all competitions under the aegis of a)
  the World Championship & Olympiad Commission or Events Commission, b)
  Continental competitions that provide qualifiers to any of the
  aforesaid competitions, and c) events listed and described in detail
  in different parts of the FIDE Handbook.
  1.13.3     New players may register themselves in FIDE Online Arena playing zone (FOA). These players are not associated to any National
  Federation, but they are assigned the FIDE flag (FID) until they
  become members of a National Federation.
  1.13.4     When a child registers at sm.fide.com he/she will be allocated a FIDE ID. If such person already had a FIDE ID before that
  registration, his/her FIDE ID will be retained and a new one will not
  be given. After upgrading to Premium at psm.fide.com, a child gets a
  CiS rating.


A conditional retrograde analysis problem Here is the problem-find a chess game that begins with 1. e4 and ends on the fifth move with knight takes rook mate, which determines who gives the mate.
This is a famous puzzle. For additional information and its history, see this nice article on ChessBase.

The solution is as follows:

   1.e4 Nf6 2.f3 Nxe4 3.Qe2 Ng3 4.Qxe7+ Qxe7+ 5.Kf2 Nxh1#


How to score a certain move in a PGN, for how well opening theory is followed I am making a bot that plays opening moves from a PGN. When the player reaches a position out of PGN, I want to give a score to the player how well he followed the PGN. What kind of statistics can I give the player for entertainment.
I am thinking:
ply The ply number that is reached.
plies to next branch Number of plies to next branch.
branches Number of branches that has been taken.
Would this be accurate, and what can I add to them?

There can't be a standard here so you can choose your scoring system in the way is makes most sense for your particular case. I'm not sure what its intent really is so it might be different from what I have in mind. We can all agree on what a 100% score would look like, but what does it really mean to have a 50% or a 75% score?
If it's intended as a training tool, I'd include the evaluation of the final position. For me it's not the same to stop following the PGN with a blunder than doing that with an interesting alternative. But maybe for your particular case it is!  It's ultimately up to you to decide. For example, I don't see why the number of branches taken should have anything to do with "how well" you folowed the PGN.
Some possible criteria you can use (I'm thinking of a training tool that helps me memorize an opening line here):

Number of moves played correctly.
Number of non-forced moves played correctly.
Number of moves until the "end" of the line.
Evaluation after deviating (compared to evaluation at the end of the line)
Mainline penalty (being a bit more lenient with errors in weird sidelines than with errors in the mainline).
Critical position bonus (selecting a few specific positions that are considered "critical" in a given line and give extra weight to those in the final score).
Previous success ratio (give extra weight in the final score to positions the user got wrong frequently in the past)


How viable is the hippopotamus defense? Clearly the defense is not viable in top level chess for classical time controls. Roughly at what rating is it viable to have the hippopotamus defense as your primary black defense?

It depends on the players and how black continues after whites moves.
For me, I find it easy to beat players using it for black.
That might speak more to their lack of experience than the opening.  But then you dont find many high rated players using it so there is no conclusive proof.


Do professional level chess players mainly stay consistent in their opening play? I know that professional chess players obviously have to have a wide repertoire and try to know as much as they can, but I was curious if they mainly stay consistent.  The reason for asking this was because I was watching the following video on Bobby Fischer and in game 6 of the world championship against Spassky, everyone was shocked when Fischer played the English Opening. It even shocked Spassky as he was not prepared to handle the English and according to the video gave Fischer a standing ovation for outstanding play, so do players of professional level normally stay consistent?  Has this changed from the past until now?

No two people are alike, and no two chess players are alike either.

To begin with, world class grandmasters study chess all the time, and they can play just about every opening under the sun and score incredibly well.

However, in order to get the very best results possible, most grandmasters will study and memorize moves and plans for a handful of openings for each color and each 1. e4 and 1. d4.  By doing this, they gain a slight advantage over their opponent in terms of a better position, using less time, or sometimes just a psychological edge.

Since the top players spend so much time learning these openings, they tend to not switch openings all that frequently.  Changing one's repertoire would require redoing all the studying and memorization that had already been done.  Frequently though, as other players discover and show new ideas, the repertoires evolve.  A player might substitute one line for another or find an improvement in some opening line.  The advent of super-strong computers has definitely increased the speed with which opening lines change.  Nowadays players must constantly be looking for improvements and tweaking their lines in order to stay on top of things.  Another factor is the internet - minutes after completion, the game is available for anyone in the world to see.  Surprises can generally only be used once.

To discuss Fischer specifically, his entire career he mostly played 1. e4 and the King's Indian Defense and the Najdorf Sicilian as black.  His openings did evolve and change over time, but he was fairly consistent, especially with 1. e4.  For this reason, when he played 1. c4 against Spassky in the '72 World Championship, it was a huge surprise.  Spassky had spent his time figuring out how to meet 1. e4 and had to readjust to play the Queen's Gambit Declined.


How would you figure out someone's Elo rating from a single game of chess? I'm basically fishing for suggestions here... there is an AI contest to figure out a person's rating from a single game. The contest's description mentions Ken Regan's approach that makes use of engine evaluations of players' moves (and the contest's accompanying game data is pre-equipped with engine evaluations for such use). What other kinds of factors do you believe would be useful for such a task?

I could imagine things like:

Ability to follow recent opening theory (for strong players)
Total number of blunders (for weak players)
At what point in the game did resignation occur? (for strong players, it often evaluates to numbers closer to a draw than for weak players)
Average depth of tactical traps avoided

Other ideas?

I also try to take part in that competition, although I'm not sure I will be able to spare the time and computational effort to actually make a submission.

Unfortunately I think the Kaggle data set of engine evaluations isn't suitable to get the best possible result. I think it is crucial to not only have the evaluation of the best move, but also of the inferior choices.
The reason is that you need to calculate some kind of measure of the complexity of the position to weight the accuracy shown by the players.

In short: It is hard to be accurate in a complex position and easy to be accurate in a simple position.

Another problem is that at a runtime of one second per move, stockfish probably isn't much stronger than the average player in the dataset (which would be around 2200 Elo) …

So to create a decent dataset one would have to invest a lot of cpu-hours. 50000 games x 40 moves x 1second (or more) >= 555 hours.

To create an opening tree that allows you to see when the players deviate from already played games and how strong the players of the played games were, is another idea to give an initial guess of the players strength.

So my rough outline is to create an opening tree to get an initial guess of the strength, ignore the moves played in the opening, weight the accuracy of the moves after the opening phase with the complexity of the position and do some kind of linear regression analysis. Maybe look out not to overvalue time trouble blunders.

I think the key is to get a good "complexity number". The other possibilities you mention … "number of blunders" just reduces "accuracy of play" to something similar with less information. "Depth of tactical traps avoided" is tricky and may computationally be even more expensive.


I'm struggling to find the full solution of a chess problem I'm starting to think that this puzzle, found on chess.com here in the 5th post down, does not have a correct full solution. But it features a nice line if Black moves wrongly, so judge by yourself.
[Title "White to move and win"]
[FEN "8/8/7B/K7/8/7p/4Bkp1/6Rb w - - 0 1"]

I think I have found the first move, after which black has two options, and I have found the solution for one of the two:

 1.Ba6 Kxg1 2.Be3+ Kh2 3.Bf4+ Kg1 4.Bg3 h2 5.Kb5 $3 Kf1 6.Kc5+ Kg1 7.Kc4 Kf1 8.Kd4+ Kg1 9.Kd3 Kf1 10.Ke3+ Kg1 11.Bf2#

The only problem is that black is not forced to pick this line, and could go for the other option:

 1.Ba6 h2

In which case i'm completely stuck. I've tried using a browser version of stockfish, which can't solve it either. So does this puzzle really have a (full) solution?

Yes, there is indeed a full solution. There is a move that you missed that wins for White after 1. Ba6!.
[FEN "8/8/7B/K7/8/7p/4Bkp1/6Rb w - - 0 1"]

1. Ba6 h2 2. Bf8!

Now, no matter what Black plays, White will play 3. Bc5 and control g1. Thus, White is able to prevent Black from obtaining a queen for long. As such, White wins as stipulated.
However, it is very understandable why one would consider the resulting position as a draw. The Shredder tablebase proves that White can squeeze out a win by slowly cutting off the Black king. It is difficult, if not impossible, for a human to even find the right ideas. Therefore, it makes sense that Stockfish can't find either, if not rather quickly. It's an easy mistake.
[FEN "8/8/B7/K7/8/5k2/6p1/6Bb w - - 0 1"]

1. Kb5 Kf4 2. Kc5 Ke5 3. Bc4 Ke4 4. Kd6 Kf5 5. Bb3 Kf6 6. Be6 Kg6 7. Ke5 Kg7 8. Bd5 Kg6 9. Bc4 Kg5 10. Bd3 Kg4 11. Bc2 Kg5 12. Bf5 Kh4 13. Kf6 Kh5 14. Bh3 Kh4 15. Be6 Kh5 16. Bf5 Kh4 17. Kg6 Kg3 18. Kg5 Kf3 19. Bd3 Kg3 20. Be2 Kh3 21. Bg4+ Kg3 22. Kf5 Kh4 23. Bf2#


Fianchetto bishop vs. normal bishop? I have found the following disadvantages of the fianchetto bishop:

1) The diagonal it controls is often blocked by the knight in its natural square.

2) The diagonal it controls is often blocked by central pawns of the same team or of the opponents.

3) Advancing the knight pawn (b2 -b3 or g2 - g3) somewhat weakens the pawn structure.

4) If the other bishop is developed along its normal diagonal, for eg.to b5,then advancing the knight pawn - b2-b3 cuts off the escape route for the other bishop - after for eg. 4) B-b5 a6 5) B-a4 b5 and 6) B-b3 is not possible because of the pawn at b3 and the bishop is trapped. So it somewhat impedes the development of the other bishop.

5) The fianchetto bishop cannot be defended by a pawn and is vulnerable to attack from the sides. Also the 'hole' in the pawn structure can make the rook vulnerable if the fianchetto bishop is moved from its b2 or g2 spot.

For these reasons, I've personally never preferred the fianchetto.

Yet, despite these drawbacks, the fianchetto development is often used in certain openings such as the Sicilian dragon and variations of QGD. Some players even open the game with the fianchetto.

So, overall, is fianchetto development a good idea and under which conditions is it justified? What are the points to keep in mind during fianchetto development?

All the things you say are true! But fianchettoed bishops have some advantages as well. Here are a few:

They control multiple central squares at once. A fianchettoed bishop attacks half of the center four squares (e.g., a bishop on g2 attacks e4 and d5). Bishops not on the long diagonals can't do this.
They also can attack multiple squares around the opponent's king at once. A Dragon bishop on g7 facing a queenside-castled king on b1 casts its eye on c3, b2, and a1.
They can attack and defend simultaneously. A bishop on g2 has a lot of influence over the center squares of e4 and d5, not to mention that it can also eye a black pawn at b7 or the rook behind it at a8. But it also protects a castled king, covering f3 and h3.
It's not easy to attack them. A bishop at b5, say, is often forced back to b3 with ...a6 ...b5. And Black often even attacks it again from there, say by ...Na5. On the other hand, a fianchettoed bishop on g2 is nicely tucked out of play. Usually the only thing you have to worry about much is an opposing bishop coming to h3 supported by a queen.

Deciding where to put your bishops involves a lot of tradeoffs, which include the positive aspects mentioned here as well as the negative ones in your question.


Using jin to play on chess.com I decided to play a few games on FICS, and I really loved jin's interface. Is there any way to tweak it so that I can connect to chess.com's server? (Or using any other interface, for that matter. In particular, are you absolutely forced to play in-browser at chess.com?)

The chess.com business model depends on locking people into using their site to play through in order to convince those users to purchase subscriptions to the site (just as is the case with Chessbase's Playchess site, the ICC, FIDE Online Arena and several others).  Opening up access to their API (they do have one for their smartphone apps) in the way you suggest could be readily used to break through those commercial barriers.  Which is a round about way of saying, no, there's not much chance of using any other program with their site.


A position in which there is no possible checkmate I saw the game Firouzja vs Carlsen in world blitz championship in which Carlsen flagged Firouzja. Carlsen won because even though he had only a bishop, there could be a possible mate position.

I am asking if there a chess position in which both players have at least one piece, not including the kings, and there is no possible future mate position?

An obvious one is if both players having only one bishop moving on the same color squares. But is there something else?

I am actually looking for a complicated position, not obvious to humans at all, which needs something like 30-50 moves deep analysis for proving there is no any possible mate position.

I think that is limited to just a few positions.

A lone king vs. king.
king and bishop vs. king.
A king and bishop vs. king and same colored bishop as the other side.
A king and multiple bishops of the same color vs. king.
A king and knight vs. king.
Any barrier position, where neither side can cross over to the other side.

Even king and knight vs. king and knight you can get a mating position.

Here is a wonderful position that I "stole" from chess.com that illustrates why that FIDE rule exists. Yes, it was probably not fair for Carlsen to get the full point, but imagine having this position, and not getting the full point.

 [FEN "6rk/4NP2/7K/8/8/8/b7/8 w - - 0 1"]

  1. fxg8=Q+ Bxg8 {By USCF, and chess.com rules, this is a draw here.} 2. Ng6#

 [FEN "6nk/5N2/6K1/8/8/8/8/8 b - - 0 1"]


Should one actively search for a checkmate ('hunt the King') in the middlegame? My usual middlegame strategy is to gain an advantage, however small (say a pawn), and convert it to a win in the endgame. I position my pieces and plan attacks accordingly, so that I can grab the small advantage I need. I don't actively hunt for the opponent's king, and prefer to first gain an advantage, so I can exchange pieces and win. So the entire game grinds on.
That said, I don't (usually) miss a checkmate if my opponent blunders in the middlegame. On the whole, though, I prefer taking the game to the endgame, even if my advantage is significant (~3 points).
However, I've seen players who actively attack the king in the middlegame itself. They position their pieces in such a manner that they threaten checkmate, and seem to plan to finish up the game in the middlegame. They try to take advantage of the castled king's reduced mobility, and checkmate him. The success of this strategy depends, it seems (based on what I've seen), on both the opponent's skill level as well as on luck.
My question
I wonder, as a general rule, what should one's middlegame strategy be: should one actively hunt the opponent's king in the middlegame itself, looking for a checkmate, or try to gain an advantage which can be converted to a victory later?

There is no overarching middlegame strategy that trumps all other strategies.

Both middlegame strategies listed are viable general strategies to play for, if the position allows it. What makes a difference are your own preferences; if you love tactics and mating attacks then you should probably go for middlegame positions that allow you to play in that manner, and similarly if you like calmer positions you should probably go for positions that aren't as sharp. Objectively speaking there isn't really much saying that one playing style is better than the other.


How do I find bitboard attack maps non-manually? I am writing a C++ chess engine based on the magic bitboard, where ordering for bitboards is from LSB to MSB in Little-Endian Rank-File mapping. I'd like to have a 6x64 dimension 2D array for all possible attack sets for each piece on every square to save time during program execution.
Is there a resource that has these bitboards already defined so that I don't have to spend several hours constructing them manually, or is there a way to generate the attack sets with a program?

Stockfish (https://stockfishchess.org/download/) is open source and uses magic bitboards.
Crafty (https://craftychess.com/) uses bitboards and is heavily commented.
There are other using bitboards, but these two are the best.
Hopefully this helps.


Why do most beginners play this line agains the Caro-Kann? Why do most beginners play this line against the Caro-Kann? 1. e4 c6 2. Nf3 d5 3. exd5 cxd5 4. d4 and 5. Nc3?

[FEN ""]
1. e4 c6 2. Nf3 d5 3. exd5 cxd5 4. d4 AnyMove 5. Nc3

It's not the best way to play against the Caro-Kann, but it's good enough for beginners. It follows basic opening principles: develop your pieces, fight for the center, knights before bishops, though it does violate the rule about moving a piece (or pawn?) more than once. It's true that the Knight on c3 blocks the natural c4 advance, but beginners can't be expected to know that (see below).

If you're seeing this a lot from opponents, don't worry. It will go away (but not completely) as your rating improves and you start playing stronger players. Beginners are commonly told not to study openings, which they interpret to mean don't even learn the first 3 or 4 moves.


slav defense, black's bishop early development punishment After:

[FEN "rnbqkbnr/pppppppp/8/8/8/8/PPPPPPPP/RNBQKBNR w KQkq - 0 1"]
1.d4 d5 2.c4 c6 3.Nc3 Nf6 4.Nf3 Bf5

I want to put a lot of pressure in black's position, I used to follow the game with:

5.cxd5

And here black has two major options:

i) 5... cxd5

rn1qkb1r/pp2pppp/2p2n2/3P1b2/3P4/2N2N2/PP2PPPP/R1BQKB1R b KQkq - 0 5

5... cxd5 6.Qb3 Qb6 7.Nxd5 Qxb3 8.Nxf6+ exf6 9.axb3

I think it's very good for white

ii) 5... Nxd5, and here I found searching in a database a move that looks like strong, Nd2!

rn1qkb1r/pp2pppp/2p2n2/3P1b2/3P4/2N2N2/PP2PPPP/R1BQKB1R b KQkq - 0 5

5... Nxd5 6. Nd2 e6 7.e4 Nxc3 8.bxc3 Bg6

And in this position white has a solid center and looks for me a little better

I want more, how should I continue after 4...Bf5?

As far as I know it is consensus that the two variations you gave starting with 5.cxd5 are indeed the best possible way to play as White.

Now 4. ...Bf5 is a bad move, as Black is either forced to give up a pawn( in the first variation) or give up the center(as in the second variation), but despite these tactical flaws it is still a sensible developing move, so you really should not expect to gain more than you do in the given variations.

That being said, White does have different options available, but none of them is actually objectively stronger. In fact, if White is careless this variation can easily result in an equal or even slightly favorable position for Black. There is a famous game Yanovsky - Capablanca, that beautifully illustrates this danger.


Iterative deepening: what should I do with previous results? I implemented a negamax with alpha beta and aspiration windows. Now, it also has iterative deepening. When I let the engine run for 15 seconds in the below position, it finds a move at depth 2 with very good value (135/ d8-d7). But when it goes one depth deeper, the movie is bad because it loses the queen (980). Looking at the best move at the deepest depth, when it fully searches, I get f7-f6 with an evaluation of 200 and it is a way better move.
Do I just throw away the best move of a previously searched depth, and only look at the deepest fully searched depth? My brain somehow can't find the solution.
[FEN "rnbqkbnr/5ppp/4p3/2PN2B1/1P2P3/p4N2/P1P1BPPP/1R1QK2R b Kkq - 0 1"]

In alpha/beta pruning, the order that moves are searched in matters a great deal. You always want the best move(s) to be searched first--this creates more beta cutoffs. The basic idea is that before searching each level of the tree, we will sort the moves based on how good they are, then search the moves in that order.
Of course, this is quasi-paradoxical ("how to find the best move: step 1, find the best move...") and one of the ways we get around that is using iterative deepening. Search the position at a smaller depth, then put that move at the very top of the list for the next iteration. This is the point of iterative deepening.

Because you are just starting out, (and are searching depth 2 in 15 sec), I'd really recommend

making sure your alpha/beta is bug free (for the love of god, use negamax)
implementing other move ordering techniques before iterative deepening.
implementing null move pruning

These last two are (relatively) easy to do, and give essentially free speedups.


What's the difference between SCID and SCID vs PC? I've got two files installed on my site from SCID & SCID vs PC - Scid vs PC-4.16.x64 & Scid-4.6.2. How are they different ? Or are they just the same ? Which one should I delete if it is a replica?
Thanks!

Shane's Chess Information Database (SCID) is a powerful Chess Toolkit, with which one can create huge databases, run chess engines, and play casual games against the computer or online with the Free Internet Chess Server. It was originally written by Shane Hudson , and has received strong contribution from Pascal Georges and others.

  Scid vs. PC began with bug-fixes for the computer-versus-player features of Scid (hence the name), but has evolved into a solid alternative with many new features and interfaces. The project is authored by Stevenaaus and numerous contributors.

So they are not the same. Scid vs. PC is a SCID variant.


I read that Mikhail Tal claimed to have been able to see 50 variations ahead in a game. Any thoughts on this possibility? Mikhail Tals' books on chess. Learning/analytic chess theory. Perception and intuition in the development of strategic and tactical chess play.

Note that "number of moves ahead" is not necessarily a great proxy for "number of positions considered". An open board with no impending threats has many possibilities of what might be the "best" move, and will require a player to analyze a wide, but shallow tree of possibilities. A board with few pieces and many threats has relatively few "good" (or even legal) moves, so a player can look farther ahead down a narrow but deep tree of possibilities. In some cases, the tree becomes a path - there is only one move to make. This question, for example, shows games with many repeated checks, making the tree of potential moves very narrow indeed.

It seems that most high-level chess players tend to think 20-40 moves ahead, depending on the board state. It's not unreasonable to think that someone could think 50 moves ahead in very particular situations, where the next few moves are "obvious" or even forced. But to be able to consider 50 moves ahead in all possible situations is likely beyond a human's ability.


Fastest way to get both kings to the other side of the board? Say that both players collaborate to get White's king to the eighth rank and Black's king to the first. What's the shortest sequence of moves that achieves this?

It can be proven that 10 moves, or 20 plies, is the least possible.
[Title ""]
[FEN ""]

1. f3 f6 2. Kf2 Kf7 3. Kg3 Ke6 4. h3 h6 5. Kh4 Kf5 6. Kh5 Kf4 7. Kg6 Kg3 8. Rh2  Rh7 9. Kxh7 Kxh2 10. Kh8 Kh1

Here is the proof, listed in a logical order.
Observations Of Proof

Both kings must make at least seven moves to get to the other rank, so that's 14 plies off the bat.
Each side must move a pawn move to release a king, which costs 2 plies in further total.
Each side must move a piece to unguard a square for the other king, also costing 2 plies.
Finally, at least one more pawn move by both sides is required in order to let each king bypass the pawn structure, and that amounts to 2 plies.

In conclusion, 14+2+2+2=20 plies, so it is indeed the minimum possible.


What's the best alternative to the 'scoresheet' blunder checking strategy? In Simon Webb's brilliant book, Chess for Tigers, he advises that a player write their move on their scoresheet before playing it. Then, right before you play your move, you check it one more time to ensure you haven't made a blunder. I used this strategy with great effect in my games, and it cut down my blunder rate considerably.

Unfortunately, Fide changed the rules, and now this kind of strategy is illegal: you have to write your move down after you play it. Is there a substitute for this strategy that still uses the scoresheet, but is legal under Fide rules?

I don't know of any proven method but here's one idea: you could try to imagine writing the move. Translate your move into algebraic notation, imagine the text on your scoresheet, maybe even trace it with your finger. Hopefully that will be enough of a pause in your train of thought to enable you to see the move from a different perspective, which I think is the rationale behind the "write before you move" approach.


Knight's opening move I generally play 1.Nf3 as white . I actually wonder whether there would be any major difference if I play 1.Na3 instead of 1.Nf3 . I am a novice player . An illustration will definitely help me in understanding the reason behind this.

To answer your question:

Experience has shown that it is a good idea in the opening phase of the game to:

develop minor pieces (bishop/knight) quickly
and to occupy the centre (squares e4, d4, e5, d5 and thereabout) with pawns and/or to attack the centre with minor pieces

In this sense Nf3 is the better (and by far more popular) move. It attacks central squares (d4 and e5) and thereby prevents black from occupying the center with e5 immediately and potentially could also support a white pawn push to d4.

Na3 on the other hand does little to get hold of the center and in addition (as with any knight on the rim), it has fewer squares to go to: 4 instead of 8.

Occupying the center is important among others because it can:

limit the space of your opponent
allow pieces stationed around there to quickly reach other parts of the board as needed

For a novice player the first move(s) don't matter. It is highly unlikely that you win/lose a game because of the difference between 1. Nf3 and 1. Na3, rather because of some tactics later on. That's why it is recommend for beginners to focus on tactics first.


Why are these weak squares important in this situation? I'm watching a video on weak/strong squares. I think that I understand the concept, but not exactly why they are important in this game (Carlsen-Karjakin):

The video explains how Carlsen maneuvered to outnumber Karjakin in number of pieces that can go into those squares. This includes exchanging his two bishops for Karjakin's two knights, in a game that a result of these changes, is opening.

My question is, why are these two squares so important? Specially b5 is quite far from both sides' kings.

PS: Carlsen indeed moves his knight to b5 later on.

The final position is a very typical position of weak bishop against strong knight.

The knight has good outposts on d5 and b5, where it is supported/protected by white pawns and cannot be challenged by any black pieces unless black sacrifices an exchange (rook for knight). Also the white knight is very mobile and can basically go wherever it wants.

In contrast, black's bishop is very passive and bound to the protection of the d6 pawn. It is hindered in activity by its own pawns and cannot attack any white pawn (because most all of them and all relevant ones are on light squares).

Furthermore black has very weak pawns which are relatively easy to attack/win. Of course care needs to be taken, because black occupies the only open file, but other than that only white has winning chances.

  My question is, why are these two squares so important? Specially b5 is quite far from both sides' kings.

The kings are both relatively safe and don't matter in this position. Basically to repeat what I wrote above: b5 and d5 are important because:

white can put a protected knight there which can not be challenged (unless black sacrifices material
if there is a knight on d5 or b5 it not only covers lots of squares, but also attacks the weak pawns (b6, d6, f4)
thanks to the knight and white pawns on c4 and e4, black cannot exchange his weak pawns on b6 and d6
the knight on b5 or d5 is very mobile and can easily move in case it is needed somewhere else

So the point/plan for white as stated in the video is to leave black with his weakest minor piece and conserve a white knight to take advantage of these weak squares.

Similar ideas appear in some lines of the Sicilian Najdorf, where white sometimes manages to exchange a dark squared bishop on f6 for a black knight, thereby reducing the number of black pieces that can cover the typical Najdorf hole (weak square on d5), while remaining with two knights and a light squared bishop all of which can take advantage of the weak light squares.


Artificially isolated pawn in the Caro-Kann I would like to know why it is so disadvantageous to have an advanced artificially isolated pawn when it can be exchanged by another pawn.
I refer to situations where a side cannot mantain such square with a pawn.

Examples:
In the Caro-Kann, after 1.e4 c6 2. e5 d6 3.exd6?!
What is so wrong with this last move?
Is it a matter of tempos (White lost two moves to go to e5 only to be exchanged ) or is there any more fundamental reason?
I know that the common thing to do for White is trying moving pawns to d4 (maybe f4, though it d be weakening).

Another example, for instance is when Black c pawn is on c5 (with a White pawn on d4) and then it is pushed to c4 before recommended. Then if White can play b3, Black tries to play b5, a6. Why not simply trade this pawn already?

The shortest explanation I can think of: if you play 1.e4 and 2.e5, presumably you want that pawn there for a reason. If you then immediately trade it off, you've lost whatever you were trying to achieve, like maybe space or central control.

In the case with ...c5-c4 followed by b2-b3: again presumably you want that pawn to be there for some reason (queenside space?). If instead you allow simply cxb3 axb3, then:

You don't have your pawn anymore
White has got rid of his a-pawn in return, rook pawns are least valuable pawns (can only capture one direction)
White has freed his a1 rook
White still has a single groups of pawns, while yours are split in the a/b pawn "island" and the c/d/e/f/g/h "island".

By adding ...b5/a4/a6/axb5/axb5/bxc4/bxc4 black also frees his rook and gets rid of the a and b pawns that could otherwise become weak later. And the c-pawn that you presumably wanted on c4 to gain space is still there.

However, I disagree that 3.exd6 is bad. White doesn't have good options there. After 1.e4 c6, 2.e5 is a bad move. It can't be maintained there and it doesn't help with the main goals in the opening (development, control of the center, and preventing the other side from achieving those).


Are there positions which cannot be properly analyzed by any computer? Are there positions in chess which every engines is unable to analyze
 properly ?

Maybe calm positions with a positional advantage the engines do not
 recognize ? Or positions won in the long term but with no concrete
 winning moves ?

8/3k4/2p5/p2p2p1/P2P2P1/2KB4/8/8 w - - 0 1

In this position the engine gives advantage of around +2.5, but as you can see, this position is a draw as there is no way for white king to enter into Black's side of the board to penetrate any of the black pawns as the black pawns control all the accessible squares which are b4, c4, e4, f4 and h4. Even though white has an extra bishop it can only attack 2 of black pawns which are on c6 and d5. Taking the d5 pawn is recaptured by c6 pawn or taking the c6 first can be defended by the black king.

This is just an example of a position where an engine can give unfair advantage to a particular side though it isn't such. Here I'm not supposed to say the engine is making a mistake because it is programmed in such a way that it sees an extra bishop and with limited depth which is below 50 it says white has the advantage of extra bishop with no strings attached, hence gives you +2.5, but if you let it think up to the depth of 50 from this particular position (for which engine might take long time), it then shows it's a draw (0.00) because of the 50 move rule which is programmed into the engines.

With many examples as such, a simple concept of long term strategy can differentiate human brains from engines. As said by @jknappan in the first answer- openings are very hard for engines to evaluate, because the engines are purely based on mathematical calculations and it does not have it's own opening repertoire and humans do have because of the long term strategy.
A queens gambit or Sicilian is studied for a long time by great chess players and they understand what kind of middlegame it will turn into and how then it can turn into a playable advantage in the endgame ( unlike the above position though by having an advantage of 2.5 and yet not able to achieve a win in the endgame). These kind of long term strategies is not thinkable by chess engines.
One more concept of bishop pair can be taken into consideration to explain the difference between human thinking and chess engines. A good chess player would not wanna give up his bishop pair in the opening unless it gives him a very good advantage. But a computer would suggest you to play and give up the bishop pair even when it's calculations gives the slightest of 0.01 worth more of marginal advantage from its second line!
These are some of the positional strategies chess engines might miss to analyze but human studies do not.


Advantage of Diagonal Opposition Suppose there are only two pieces on the board, black king and white king. Black king is at g7 and white king is at e5. It's Black's turn to move. So in this case white has the opposition. Black now plays Kg6.
Can white reach any of the last three squares f8 or g8 or h8. If the answer is "no", then what's the advantage of having diagonal opposition ?

Diagonal opposition can be thought of as a means to an end. No matter where your opponent's King moves, you can get direct opposition sooner or later. Examples from your position:

1...Kf7 2. Kf5 (White gets the direct opposition).

1..Kg6 2. Ke6 (White gets the direct opposition).

1...Kg8 2. Ke6 Kh8 3. Kf6 Kh7 4. Kf7 (White gets the direct opposition).

As per your question regarding f8, g8, and h8, White could not reach the squares even if he had direct opposition in a similar position. Put White's King on e6, and Black's King on g6 (Black to move). You'll find that Black can defend the 3 squares, despite White having the opposition.

The purpose of opposition is that it forces your opponent to move his King out of the way, letting you pass in one way or the other. Note that the way your opponent moves his King out of the way is up to him, so he could protect f8, g8, h8 indefinitely by keeping his King there. However, that would let your King pass his by playing Kf5, Kg4, Kh4 (and reaching the h-file, if that was your goal).


draw game on lichess after 2 repetitions? I was playing this game with white

https://lichess.org/INsUhHEO

I was losing, so I was happy to see the 3-position draw button appearing, which I clicked.

But after, reviewing the game, I couldn't see a reason for that to happen, I see only 2 repetition...

Where am I wrong?

Thanks

The same position appeared after 56. Kf8, 58. Kf8 and 60. Kf8 -- 3 repetitions of the position (not moves).


If an opponent's clock is pulled, how much extra time is given? Today at the local tournament I noticed something strange. It was my turn, and my opponent's clock was running.
My opponent had pulled the time control of his neighbor, accidentally. We were playing two on each table, sitting four people on each table in a room. Some time had gone while our dear neighbor had lost time on the clock. Naturally, we did like this, pulling his clock. How much extra time would our neighbor get, the one whose clock had been pulled?
I called the judge and we tried to correct the mistake in a very improvised manner.
We did not know how long it had been this way. What to do?

First of all: unbiased sources might be available. A spectator might have noticed it or a player might have recorded clock readings on the scoresheet. DGT boards record the exact time, too.
Naturally, the player who lost time should get back exactly the time he lost.
Now three unreliable sources of information are available to the arbiter: the person who accidentally pressed the wrong clock and the two players on the other board. They should be able to agree on a rough estimate of the time elapsed. (Has it been five minutes or ten? You should be able to tell.) The arbiter should adjust both clocks accordingly, maybe adding a minute for the disturbance caused.
This is governed by article 6.13 in the FIDE laws of chess:

If an irregularity occurs and/or the pieces have to be restored to a previous position, the arbiter shall use his best judgement to determine the times to be shown on the clocks. He shall also, if necessary, adjust the clock’s move counter.


In Caro-Kann, which one is less risky, the main line or the Steinitz? After 1. e4 c6   2. d4 d5   3. Nc3 dxe4   4. Nxe4, the most popular move (main line) is 4...Bf5. But former world champion Anatoly Karpov seems to like 4...Nd7. Since Karpov's style is "solidly positional, taking no risks but reacting mercilessly to any tiny errors made by his opponents,"
 I am wondering if 4...Nd7 is generally considered more solid and less risky than 4...Bf5, at least by Karpov.

I am hoping that Anatoly Karpov can answer or comment on this question, but it does not seem realistic.

Regarding your question, as far as I remember, both lines hold.

Bf5 gave White a lot of options to fight for an advantage. It got revamped with the help of the computers, Black seeking to generate more active counter-play by castling short instead of long, but I had no courage to try those positions out as they were too wild for my taste.
Nd7 was regarded as more solid, giving White less attacking options, but also requires more enterprising play from Black.

Sadly, user q.undertow is right. There is no safe line in the Caro-Kann.

Allow me to explain why:

Since it's creation, it was considered inferior to French defense, masters arguing that 1...c6 is too slow, Black not fighting energetically enough for the center. This fact gives White enough time to put pressure on Black. This will always be the case with Caro, Black argues that he will be able to withstand the pressure and cash in White's over-extension in the endgame.

In some lines, White plays outrageous moves, almost "all-in"-ing, forcing Black to invest reasonable risk, in order not to lose. These positions are ugly for the eye of the beholder, but that does not matter. What matters is that objectively, the positions are sound and not inferior for Black.

Before the endgame, comes middlegame. Relinquishing initiative to White, Black will have to defend some serious threats and nobody in the old days knew just how far can White go with his aggression. They tried to play positionally, relying on general principles, but this approach gave only a small plus for White, so he turned to "all-in"-ing, backed by computer analysis. These new moves broke every principle they could, but still remained viable, forcing Black to reply in equal manner in order not to get crushed, generating mind-boggling positions.

Sadly, it is White who steers the game, so if he wants to, he can drag you into sharp positions. Positional lines hold for Black (last time I checked) so you should have no problems there as their plans are not difficult to grasp.

If you do get dragged in the complications, book yourself up, you won't be able to save yourself with calculation and general principles. From my experience, it was harder to play as Black, more stress, easier to make a mistake, less options to generate counter-play...


What should a player do when their opponent asks to see your notation sheet during a game? During an over the board tournament, an opponent frequently asked to see my scoresheet, stating that they had missed moves or otherwise messed up theirs. (They asked 5 or 6 times in a game with a time control of game in 25 minutes.) Trying to keep things friendly, I let them see my sheet. The first couple times I did not mind, but when it continued happening I found it annoying and distracting.
Thus the question: Am I obligated to let an opponent see my game record so they can make corrections to theirs?
Also, if I do show it to them, whose clock should be running as they make corrections?

Am I obligated to let an opponent see my game record so they can make corrections to theirs?

According to USCF rule 15D3, it's suggested that you do so, but it's not mandatory unless the tournament director tells you to:

The opponent is urged to comply with such a request, but this is not mandatory. If the opponent denies the request, the player may stop both clocks and see a director. A director who agrees that the request is appropriate shall instruct the opponent to lend the player the scoresheet. The opponent may not refuse as all scoresheets belong to the organizers.

The TD will probably allow it, unless there's some reason not to. Excessive requests may be denied and may even be penalized, according to rule 15D4.

Also, if I do show it to them, whose clock should be running as they make corrections?

According to USCF rule 15D2:

The clock of the player making such a request is running and shall continue to run until the scoresheet has been returned.

Under FIDE rules, the time control in question would be a Rapid game. According to FIDE rule A.3.2, which applies to rapid games:

The player may at any time, when it is his move, ask the arbiter or his assistant to show him the scoresheet. This may be requested a maximum of five times in a game. More requests shall be considered as a distraction of the opponent.


Why struggle for a single pawn? I've seen many chess games, where after a certain point, one side maneuvers their pieces (like doubling the rooks) to target a single point. Most of time it's a pawn on the wing and the other side tries to defend their pawn. But why struggle for a pawn?

As the old poem says:

For want of a nail the shoe was lost.

For want of a shoe the horse was lost.

For want of a horse the rider was lost.

For want of the rider the message was lost.

For want of a message the battle was lost.

For want of a battle the kingdom was lost.

And all for the want of a horseshoe nail.

Exactly the same principle applies in chess. Usually the loss of the pawn results in the loss of the file, loss of control of the file allows the rooks to penetrate and the position soon collapses.


What is the solution to this mate in 2 puzzle? What could be the answer to it?


Spoiler-free chess replays for the 2013 Candidates tournament I am looking for replays similar to chessgames.com's format but which don't contain any spoilers (winner, list of moves, text or images that could give a hint as to how the game went on...) to enjoy as much as possible the games of the 2013 Candidates Tournament currently being held in London:

Does anyone know about a website offering such replays?

PS: just to clarify, I'm not looking for live coverage, such replays posted once the game has been played.

If you use Scid, then you can turn on the option "Hide next move". That also hides the result of the game. The option is intended for training purposes (solitaire chess, also known as "guess the next move").

You can download a PGN file of the games, and open it with Scid. Don't open the game list window (because it shows results), but first turn on the hide next move option and then choose "Next game" (ctrl-down).

That's one way.


Forced mate: 2 queens vs king On the board, there are 2 queens (of the same color) placed on random squares. The opposing side has only a king, placed on a random square (and not in check). There obviously exists a mating sequence. What is the biggest possible 'n' such that there is a forced Mate in 'n'? In other words, given the above situation, what is the upper bound on the minimum number of moves required to give a checkmate?

The longest K + Q + Q vs K mate whilst maintaining optimality is a mate in 4.


How does "time odds" confer an advantage to the weaker player? Ok, we set the clocks so that the weaker player gets 15 minutes on the clock, and the stronger player gets only five. In theory, that gives the weaker player three times as much time to think, which should be an advantage.

Except that the stronger player can use the weaker player's time to think. OK, the weaker player has "extra" time to think out a response to the stronger player's last move, but the stronger player can be thinking about the same possible responses (and more). When I am the stronger player (seldom), I can usually anticipate the weaker player's response, plan my countermove, etc., all on the other player's time. If a computer were the stronger player, this advantage might be even more pronounced, because a computer can "think" in nanoseconds.

Apparently, this is not the way things work (yours truly aside)? So how does a time advantage confer a meaningful advantage to the weaker player? Is it necessary to force the stronger (human) player to "look away" from the board during the weaker player's turn so that the stronger player doesn't benefit from the weaker player's time?

Indeed, you can think on your opponent's time. However,

Your opponent may make a move you didn't expect
Your calculation may be slightly worse because you had to see one ply farther
Even if he played a move you expected, you may have been looking at four possible moves of his, so you only spent 1/4 of your thinking time on the move he actually made
If he played his move relatively quickly, you're thinking on your own time basically from the start

As you point out, having less time doesn't give you as big a disadvantage as it might first appear. However, it is still a real disadvantage. If you think the penalty is not great enough for a given match, just increase the time difference.


Hanham Variation Philidor Defense I want to find a way of transposing into the Hanham Variation of the Philidor Defense, without a way for White to deviate. For example, in the normal move order, White may have the move 3. Bc4 or 3. Nc3, which I want to avoid. I have tried the Pirc defense, but it doesn't work. Is there any other opening which will transpose?

No.  Black cannot reach the Hanham variation (e.g. the Philidor setup with Nd7, Nf6, e5 and sometimes c6) by force.
The modern move order to reach the Hanham variation, however, is 1. e4 d6! 2. d4 Nf6 3. Nc3 e5.  This is black's best move order to reach the Hanham variation because white usually transposes to the Hanham variation with 4. Nf3.
Experienced white players usually don't avoid the Hanham with the above move order because the main alternative 4. dxe5!? lets black equalize easily as recent results have proven.


Weird early f4 suggested by engine (English Opening: Reversed Sicilian) I have played a game recently and at move 7 the engine suggested f4 as best continuation, but I failed to understand why. When I see the move, all I see is a super weakening move, especially with a lot of pieces on board. What might be the idea(s) behind this move ?

[FEN ""]

1. c4 e5 2. Nc3 { A21 English Opening: King's English Variation, Reversed Sicilian } Bc5 3. Nf3 Nc6 4. Nxe5 Nxe5 5. d4 Ng4? { (0.43 → 2.98) Mistake. Best move was Bd6. } (5... Bd6 6. c5 Be7 7. dxe5 Bxc5 8. Bf4 Ne7 9. e3 Ng6 10. Bg3) 6. dxc5 Qf6 7. Ne4? { (3.17 → 1.96) Mistake. Best move was f4. } (7. f4 Qc6)

It is either f4 or f3 to defend the threat on f2.  Intuitively I prefer the tempo that f2-f3 gets, but the idea of f2-f4 with e2-e4-e5 is probably what the computer likes.