Why do we increase depth of search for a mate detection in alpha beta pruning?

I can see more than one reason for that.

One reason is that after a check there are very few moves available: usually there are 30 moves available, but after a check there are usually at most 4 or 5. So that move doesn't count as a full ply if you want to measure the size of the resulting tree, and in the same search time you can go deeper.

Another reason, and I think it is the most important, is that a check is a forcing move, and consequences of a forcing move must be considered more deeply. So it is good to go deeper after a check.

Note that in this way, the program will tend to analyze all forced sequences of consecutive checks very deep, in this way it can easily find all perpetual checks and many forced mates. So this is can be very useful.


Play. Read. Solve tactics problems, repeat. Solve endgame problems. Solve middle game problems, repeat. Analyze positions in your head. Learn famous chessgames by heart, and why specific moves was played. One of the best players in Russia had learned by heart 'all' games played by Fischer. Most average players could probably replay 50+ memorized chessgames. Find a friend to do these things together with. Or a trainer. Join a chessclub! Analyze your own games. Take help from people better than you. For tactics I like www.chesstempo.com


At what point is sacrificing a queen a bad move?

If you can't calculate a clear win after sacrificing your queen, do not do it.


Knight vs bishop endgame in Fabiano Caruana vs Hou Yifan 2018

This was a great game! Hou Yifan brilliantly outplayed her opponent  Fabiano Caruana in a very positional middle game, and mind you using the Petroff's defence in the opening, which is Caruana's specialty by any stretch of the word! The endgame was very tricky, and Caruana proved his resilience and held the game to a draw in a very resourceful way, despite there having been missed chances for black.

The short answer is: yes there was at least one key moment where black had a forced win in the N+4p vs B+3p. Having traded into a better endgame, pawn up and knight vs bishop, one of the critical moments of the game was after white's 64.Bb7 move, harassing black's pawn backbone which all lie on light-squares, at this moment black had in fact the possibility of achieving a pawn breakthrough, and create a passer!

 [title "Position after white's inaccurate 64.Bb7"]
 [fen "8/1B6/p7/1p1p4/2p2n2/P1P1k3/1KP5/8 b - - 13 64"]
 [startflipped "0"]

To see the pawn breakthrough, the idea to spot is: noting that white's bishop is locked out of play by black's pawns on light-squares, once the black king gets to d2, the two kings on b2 and d2 are in opposition, and had there been no white blockaders on c2-c3, black would just advance their own c pawn and promote (diagram):

So the question is: how could we create this desired pawn breakthrough, or in other words,

Can white's c2-c3 pawns be removed after Kd2?

First key move is Nd3+!! The knight sacrifice removes the c2 blockader, and if white were to accept the sacrifice, then d4
removes the 2nd blockader (c3) and black's c pawn advance with check and promotes since the bishop is too slow in reaching the a4-d1 diagonal to eye c2. Summary in diagrams:

But does white have to take the knight on d3?

Well, let's consider the only reasonable king move: Kb1, as anything else just leaves both c pawns hanging to black's king. Then, the same pawn breakthrough on the c-file can be achieved, with the difference now that we first win the c2 pawn with Ne1-Nxc2 and then play d4. Let's see in diagrams:

and black again promotes a pawn on the c-file, as in the rightmost diagram:

if white takes on c4 then dxc3+ Ka2 and Nd4 wins by preventing Bb3 and the c pawn runs.
instead, if white plays Ba4 immediately to cover c2, then dxc3+ Ka2 and Nd4 wins again since now black has two c pawns and white's bishop can only be sacrificed for one of them.

And here's a summary of all the discussed variations:

 [title "Pawn breakthrough for black"]
 [fen "8/1B6/p7/1p1p4/2p2n2/P1P1k3/1KP5/8 b - - 1 1"]
 [startflipped "0"]

 1... Kd2 {key starting move of the winning line, attacking both white pawns and covering the path for a pawn to promote along the c file.} 2. Bxa6 (2. Bc8 {an attempt to immediately re-route towards the defense of c2, but it is too slow and irrelevant as Nd3 still works} Nd3+ 3. Kb1 {cxd3 loses similarly to d4} Ne1 4. Bf5 Nxc2 5. Bxc2 Kxc3 {and black's connected passers win easily.}) Nd3+ 3. cxd3 (3. Kb1 Ne1 4. Bxb5 Nxc2 {Nxa3+ fork threatened} 5. Kb2 d4 6. Bxc4 (6. cxd4 c3+ 7. Ka2 Nb4+ 8. axb4 c2) (6. Ba4 dxc3+ 7. Ka2 Nd4 {and one of the c pawns promotes}) dxc3+ 7. Ka2 Nd4 {preventing Bb3 and c-pawn runs}) d4 4. cxd4 c3+ 5. Ka2 c2 {and black promotes}

So it's safe to say, Kd2 followed by Nd3+ was winning by force. What a beautiful pattern!

Note that, at the stage of the game that we are talking about here (around move 64), the players were playing by rote as they were relatively low on time, so Hou Yifan played the very natural a5 in reply to Bb7 (which in hindsight now we know to have been a blunder) and the winning pawn breakthrough was missed. She might have considered it but maybe couldn't work out all the details, e.g. the lines where white doesn't accept the sacrifice. Therefore, they played pragmatically considering their energy and remaining time on the clocks. Admittedly, even with more time, these strange pawn breakthroughs are never easy to spot, and tend to require a more relaxed mindset (like when one solves studies, and thus knows there's something to be found), and are often times missed/dismissed in practical play.

Reminds me of Kramnik vs Anand (world championship 2008), where Anand found a beautiful breakthrough in this position:

 [title "black to play and win"]
 [fen "8/1R3p1p/4pk2/8/PP3pn1/8/5PPP/2r2BK1 b - - 0 1"]
 [startflipped "0"]

The analysis is left to the reader ;)


Controversy over the Xiangqi cannon piece?

The character 砲 (pào) gives a significant clue:  compared to 炮, which is homophonous, the radicals of these characters are different.  砲 uses the 石 radical, which means stone, and 炮 uses the 火 radical, which means fire.
Although cannons were not yet invented until, as you say, the 12th century, trebuchets -- weapons of super long range that used stone -- predates the cannon by hundreds of years.


Why doesn't white play Bd2 after this ...Qa5+?

The point here is that Bd2 blocks your queen's mobility and also leaves the defense of the d4 square. So after say Qb6 you pretty much have to go back with Be3, which will move closer to a draw by threefold repetition if blacks continues again with Qa5+.

Also if after Qb6 you play c3 instead of going back with the bishop, now your bishop is not well placed, and black's Queen on the other hand is very good on b6. So its safe to say that you kind of lost some piece coordination in the process.

One of ideas behind Kf2 is that you are pretty close to castling by hand with only two moves, such as Bg2 and Re1, and on the other hand black's Queen is misplaced on a5 and will most likely reroute later on to other squares.

All this being said, its still important to note that Bd2 is not a bad move. When i let Stockfish run for one or two minutes i see a diference of 0.1 for both moves. It gives 0.4 for Kf2 and 0.3 for Bd2, so its just an ok move.


Why is there a craze of becoming chess grandmaster?

Napoleon put it succinctly:
A soldier will fight long and hard for a bit of colored ribbon.

Just a couple of points:

It is the same reason that students love getting "gold stars," and why there are so many badges on StackExchange itself. There have been volumes written on the power of peer recognition.

In particular, chess titles (for the most part) are a direct result of chess achievement. FM, IM and GM titles are all well-earned. No matter how much we might not care for a person, we know that if they have a chess title, they earned it. A GM title is the highest formal title, and it serves to inform your peers (and often yourself) that a certain level of expertise was attained.


Why is it so hard to find a free downloadable chess database with older/historical chess games?

I invite you do it yourself...

  https://github.com/student-t/ExtractPGN

This is my Python repository for web crawling chess games. I use it to extract PGN chess games from Chessgames. This is an example of the games I extracted:

http://smallchess.com/Games

It's trivial to change the code such that you extract all games from chessgames (entire database) into a single PGN file. I believe you're a programmer, so that shouldn't be an issue for you.


Which chess player has the most openings named after him?

Nimzovitch.

NimzoIndian Defense: 1.d4 Nf6 2.c4 e6 3.Nc3 Bb4
Nimzovitch Defense: 1.e4 Nc6
Nimzovitch Attack: 1.Nf3 d5  2.b3 (1.b3 is the Nimzo-Larsen Attack)

Nimzovitch Variations:

Sicilian Defense: 1.e4 c5 2.Nf3 Nf6
Queens Indian Defense: 1.d4 Nf6 2.c4 e6 3.Nf3 b6 4.g3 Ba6
Falkbeer Counter-Gambit: 1.e4 e5 2.f4 d5 3.de5 c6
Falkbeer Counter-Gambit: 1.e4 e5 2.f4 d5 3.de5 c6 4.e4 Bb5+ *
Nimzovitch QP Defense: 1.d4 Nf6 (most sources attribute it to Bogoljubow)
Latvian Counter-Gambit: 1. e4 e5 2. Nf3 f5 3. Nxe5 Qf6 4. d4 d6 5. Nc4 fxe4 6. Ne3
Philidors Defense: 1. e4 e5 2. Nf3 d6 3. d4 Nf6
French Defense, Advance Var-Nimzovitch Var: 1. e4 e6 2. d4 d5 3. e5 c5 4. Qg4
French Defense, Nimzovitch (or Winawer) Var: 1. e4 e6 2. d4 d5 3. Nc3 Bb4
Four Kts Opening, Nimzovitch or Paulsen Var: 1. e4 e5 2. Nf3 Nc6 3. Nc3 Nf6 4. Bb5 Bb4 5. O-O O-O 6. Bxc6
English Opening, Nimzovitch Var: 1.c4 e5 2.Nf3
Benoni Defense, Nimzovitch or Kts Tour Var: 1. d4 Nf6 2. c4 c5 3. d5 e6 4. Nc3 exd5 5. cxd5 d6 6. Nf3 g6 7. Nd2
Caro-Kann Defense, Nimzovitch or Tartakower Var: 1.e4 c6 2.d4 d5 3.Nc3 de4 4.Ne4 Nf6 5.Nf6+ ef6
Ruy Lopez, Steinitz Var - Nimzovitch Attack: 1. e4 e5 2. Nf3 Nc6 3. Bb5 d6 4. d4 Bd7 5. Nc3 Nf6 6. Bxc6
English Opening - Four Kts Var - Nimzovitch Var: 1. c4 e5 2. Nc3 Nc6 3. Nf3 Nf6 4. e4
EO - Nimzo-English Opening: 1. c4 Nf6 2. Nc3 e6 3. Nf3 Bb4

Notes: Simon Winawer played the "Winawer Variation" of the French Defense once in his entire career; why it's named after him instead of Nimzovitch who really popularized it is a mystery (to me at least). And no, Winawer does not deserve the credit for playing it first (if he even did that) many openings are named after the masters who hammered out the theory of them and/or made them popular. Ergo the "Advance Variation" of the French Defense should also be named after Nimzovitch!

SOURCES: "The Oxford Companion To Chess" by David Hooper & Kenneth Whyld, 1984; p 226
http://www.chessvideos.tv/chess-opening-database/search/Nimzovich-variation
http://www.365chess.com/eco/C62_Ruy_Lopez_old_Steinitz_defence_Nimzovich_attack


Can I improve my chess? Or am I too old?

There is never too late to learn anything (chess, phd, new job, skateboarding). Also you have really small chances of being new superGM :-).

Analyse, not just play. Each game you lost you should review and try to understand why exactly have you lost. Your analysis should depend on your chess level.
Learn standard openings (first starting moves and be sure that you know how to reply to them as well as easy traps to avoid and exploit). No need to go too deep (trying to memorize 15 moves if you are on 1100 level), start with 5 moves and try to understand the reason with them. While doing this look how to reply to standard opening that people use against you.
Solve puzzles
Learn standard endgames like mating with Q or R, to be able to win in easy situations

And do not be scared (you aren't in a boxing match where you can have some problems if you lost). All you are losing are the imaginary points on the imaginary server to an imaginary guy whom you most probably will never see again. There are things in life more scary than that.


Doubling pawns on the c file in King's Indian

In that line you posted I'd imagine black would ideally try to blockade d6 with a piece, say via Ne8-Nd6, then begin pawn storming the queenside with a6-b5, or Rb8-b5, or something along those lines. The actual attack itself would be complex, whether to push c4 or b4 first for example, and may need additional piece development to prepare it, as well as accurate calculation to prevent white from being able to blockade the pawn storm.

As far as white attacking on the kingside, it's not so easy to attack into a fianchetto and would likely require a piece sac to break through.

I don't know the variation in question but that's how I'd play it.


The difficulty of finding the exact losing move

Sure, examples exist. E.g. Game 6 of Carlsen-Caruana, World Chess Championship 2018:

[FEN "5k2/8/5pK1/3B1P1P/3n4/8/3b4/8 w - - 6 67"]

Kg6? loses, but no human would have found the refutation.

As for games where the exact losing move cannot be found even by the best current engines - I spoke to a correspondence chess expert recently, and I'm confident they don't exist. Given a decisive game, an expert correspondence chess player will always be able to find the losing move, but it will not be trivial, and a lot of analysis is required.


Bela Berger and Blindfold Chess: What do players "see" on the board?

That's pretty much what I "see".  I don't have a mental picture of pieces, I have a "feel" for their mobility.
One of the interesting thing about blindfold players is that they each have their own way of seeing the board.


What's the problem with the Austrian Defense?

After 3. cxd5, any sensical black response is met with 4. dxc5. The time it takes for black to regain those pawns is lost on white's development, e.g. 4... e6 5. e4! exd5 6. Bb5+ Nc6 (or Bd7 7. Bxd7 Qxd7 8. Nd2) 7. Nc3.

White's opened up the center - favorable because of black's daft, dithering development - and obtains a game with winning chances.


Is acceptable to consult with your team during a match break?

I haven't seen the series, but this was a quite common practice known as adjournment. It is indeed legal to ask for outside help, in the form of teammates and even computer programs during adjournment. However, they rarely happen anymore:

With the advent of strong chess playing computer programs, which can be used to analyze adjourned positions, most tournaments have abandoned adjourning games in favor of shorter time controls. The first World Chess Championship not to use adjournments was the Classical World Chess Championship 1995, while the last one to use adjournments was the FIDE World Chess Championship 1996.

The Laws of Chess still have guidelines for adjournment, so it's possible to organize a tournament with these breaks, but I can't remember a recent high-level tournament which had them.


https://www.chess.com/blog/zaifrun/creating-a-chess-engine-from-scratch-part-1
http://mediocrechess.blogspot.com (a blog that gives you some ideas how chess engine works)

How you would approach the problem:

Check out chessprogramming.wikispaces.com. This'll be your reference site.
Create an account at talkchess.com. All the best engine developers are there. If there's an engine question that you can't find an answer there, you won't find it anywhere else.
Check out the TSCP engine source code. TSCP is a simpler but working implementation chess engine. Easier to read than Stockfish.
Do something. Try to write a chess board generator. Check the reference sites above. Study how TSCP does it.
Compare your PERF results with https://chessprogramming.wikispaces.com/Perft
Write a simple position evaluation with materials only. Copy the PST table from TSCP or the chessprogramming site.
Write a simple nega-max and alpha-beta search.
Read about UCI protocol
Add transposition table
Add simple null-move pruning


Why is the engine evaluating against bringing more attackers in this
  position?

That's not what it is doing. It is evaluating against blundering a draw. After Rb8 your queen has nowhere to go apart from allowing a repetition. If you play Qxa6 you are just a piece and a pawn up for no compensation.

[FEN "r2qk2r/pQpbbppp/n2p1n2/3Pp3/4P3/2N1BN2/PPP2PPP/R3KB1R w KQkq - 0 1"]

1. Bxa6 (1. Qxa6) Rb8 2. Qxa7 Ra8 3. Qb7 Rb8=


Web Interface for training by dragging and dropping pieces

There's also the lichess board editor. It supports all the features you want, and will also let you get a computer analysis or play the position against the engine.


Websites for creating tournaments with different starting positions

You can do this

For free

at https://lichess.org. Go to the "Play" tab, and select "Tournaments." Assuming that you have a lichess account, (all they need for that is your e-mail, and they do not spam it) you will see an option to create a tournament. Once you select that option, you will be able to specify the start position in the tournament (this position must be an opening with an ECO code).

If you wish to have only your students playing in the tournament, you can make the tournament private (password required to enter) and send the password to your students.

You can also play a game (not tournament) from any legal position (opening, endgame, middlegame, whatever) via the board editor, which is under the "tools" tab


According to this link, the World Blind chess championship includes IM-strength players.

A separate rating system isn't used but one cannot accurately compare ratings from two different player pools.

According to this link, the 2009 Blind US champion was a USCF Expert.

Roughly, I'd say being blind costs 600 rating points. Why? An USCF Expert is around 2100, the USCF National champion is about 2800, so subtraction gives 700. Similarly, a super-GM has about 450 more ELO points than an IM (2400 vs 2850)  700... 450... call it 600...)


Using chess engines to find moves sequence to make a position

Yes and No, but be warned, the possible paths to search through grows exponentially as your N increases.

The short answer is NO, unless you find someone who is doing research on chess and is using an engine for the special case like you are describing.

BUT

If someone were to do research on this special case he would setup his experiment probably like this:

First set an engine to calculate at a fixed depth 1 for the current position and make it return all variants it is evaluating. In effect this will return all possible legal moves from the current position.

All you need to do now is write your own breadth-first search algorithm, set to depth N, that can go from one state to another by using the cofigured engine.


Why can't I find any tactics in this game?

I know every tactical theme pin, fork, weak backrank, deflection, etc.
But upon analyzing this game, couldn't find any.

If you can't recognize a pin (e.g. 9. Bg5) then you don't know what a pin is. Here are 4 tactical themes in the first 20 moves:
9. Bg5 - pin
12. e6 - discovered attack
17. Qe3 - pin
20. ... Qxe6 - self-pin

How can I improve my recognition of tactics?

First you have to learn what they are.

Bg5 pins the knight against the queen. There is no immediate threat, there doesn't have to be, but this move means that the knight can't move without exposing the queen to capture.

There are "hard pins", where a piece is pinned against the king and it would be illegal to move the piece, and "soft pins", like here where moving the pinned piece would expose the piece behind it to capture.


Is FIDE president Kirsan Ilyumzhinov a good chess player? What's his Elo rating?

According to the source provided by @Lynob, Kirsan Ilyumzhinov had a rating of 2300 and was local champion of Kalmykia at the age of 14 (see also here). The game you mention against Alexander Zakharov took place in 1978, when Ilyumzhinov was about 16 years old.

However, and as you say, Kirsan Ilyumzhinov is unrated at the moment according to FIDE. But according to the same source he has played 9 rated games (not enough to get a rating). Making some research I found he played these games in the Members Appreciation Blitz Tournament in Skokie (USA) in 2012 with a result of +4 =1 -4.

Appart from that, I think he mostly plays friendly games. If you search "Kirsan Ilyumzhinov plays chess" in Google you'll find some images of him playing with different people, such as Gaddafi, Steven Seagal, the Minister of Sports Affairs of Oman or a Paraguayan student.


Looking for a Horrible-by-design chess engine

You have a whole list at http://www.computerchess.org.uk/ccrl/4040/

If you're looking for a weak engine, I'd suggest:

Predateur 2.2 64-bit
MicroMax
CupCake
BikJump

I know those four engines work and run smoothly, although they're quite weak (which is exactly what you want!). Any Elo 2000 rated human player can trash them easily.

__ My Recommendation __

If your engine can't even beat the lowest Stockfish level, maybe it'd be a better idea to focus on your engine, such as adding easy technqiues like null-move pruning. As an average human player, I can consistently beat the lowest Stockfish level, it plays around 1500-1600 level. Even the engines I mentioned might be too strong for you.


Why is ...a6 played in the Exchange Slav?

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


"chess problem" software (free/paid) to download for PC?

LucasChess is the best free software out there. You can add any engine you like and you can analyze your games with multiple engines. It also has a training mode for tactics, openings, and endgame.

I highly recommend it. I recommended it to a friend who loved it so much that he hardly uses his Chessmaster these days.

Here's the link:

https://www-lucaschess.rhcloud.com/


Stockfish perft displays reversed game notation?

The number of nodes from your perft results is identical to Stockfish (1486), so I think your implementation is correct.

How you report the individual moves is unimportant. The format is not part of perft, you can report it any way you want, Stockfish can do it anyway it wants. There is no standard. There is no rule that you have to report the root moves or the leaf nodes. This is implementation defined. In my own implementation, I'd just report 1486.

You just need to get the number correct.


Identify a problem where a potentially winning move draws because of the 50 move rule

There are dozens of problems that illustrate a potential winning moves that instead leads to a draw because of the 50 move rule.

One example is the following mate in four published by Léon Loewenton in 1956 :

[fen "5KBN/p2ppp1r/1p4pp/b7/RP6/1PP4P/1RpPPPkP/n1B1Q1N1 w - - 0 1"]

1. Nf3 Rg7! 2. Kxg7! (2. Qg1+?? draws)

There is an apparent mate in three moves: 1. Nf3 followed by 2. Qg1(+) and 3. Qg3 mate.

However, after 1. Nf3 Rg7! 2. Qg1+ black claims a draw according to the 50 moves rule (the retrograde analysis is left as an exercise to the reader!).

If white plays 2. Kxg7!, the capture breaks the 50 move chain and white can mate with 3. Qg1(+) followed by 4. Qg3 mate.


Why is 5...Be7 played before ...b5 in the main line of the Closed Ruy Lopez?

After 5....b5 6.Bb3 Be7, white has the strong option to play 7.d4. Now, 7....exd4 is a mistake, as white obtains a big advantage after 8.e5 Ne4 9.Bd5, which was played in Grischuk-Nepomniachtchi (blitz). Instead, 7....d6 is more stubborn.

In contrast, after 5....Be7, 6.d4 is relatively harmless for black, for example 6....exd4 7.e5 Ne4 8.Re1 Nc5.

      [StartPly "9"]

      [FEN ""]
      1.e4 e5 2.Nf3 Nc6 3.Bb5 a6 4.Ba4 Nf6 5.O-O b5 (5...Be7 6.d4?! exd4 7.e5 Ne4 8.Re1 Nc5) 6.Bb3 Be7 7.d4! exd4? (7...d6) 8.e5 Ne4 9.Bd5


Beginner Chess Question: Bringing out my queen early?

Common wisdom is that bringing your Queen out early invites attack and eventually costs you time. And losing time is like giving your opponent free moves. So for players of a certain level, it is true that bringing out the Queen early is not helpful.

That being said, chess is a game between 2 people. It is not between "olde GM lore" and a person.

If you're having fun bring your Queen out early, or if you're winning games by doing it, then keep doing it. If you're playing tournaments, your rating will rise accordingly. By the last rounds you'll be playing the better players in your bracket.

At some point, your opponents will get stronger. You'll notice that an early Queen sortie is a detriment. At that point you'll need to up your game.

Consider not moving your Queen until you have at least 2 other piece off the back row. Getting those pieces 'out of the box' will go a long way towards giving you some good games.


Are there any rules for transgender players in chess?

I'm wondering if there're any rules concerning transgender people in
  chess.

I asked this question or something very like it of someone who was in a position to know. Basically if your sex is recorded by FIDE as "M" and you tell them it has changed to "F" (actually your federation has to tell FIDE. Not you since FIDE trust the federations who they know rather than the players who they generally don't know) then FIDE will change your records to reflect this fact. Similarly if you choose to go in the opposite direction. I should add that I asked this question in a spirit of intellectual curiosity rather than personal interest :-).

  If Carlsen (as of time of writing the [male] World Chess Champion)
  decides to sex change, are there rules that bar him (her?) from
  competing in Women-only competitions?

First you should know that there is no such thing as "male" World Champion. Carlsen is world champion, period. If one of the top women players qualifies to play him (or another person) for the title of "World Champion" and wins then that woman would become World Champion.

If Carlsen decides to change sex then she would, of course, be eligible to play in Women-only competitions.

  If Carlsen decides to sex change, does he instantly become the Women's
  World Chess Champion?

Your question is grammatically wrong. It should read "does she instantly become the Women's World Chess Champion?"

The answer is, of course, "obviously not". There is a cycle of tournaments which anybody wanting to become Women's World Chess Champion must compete in and succeed in to become Women's World Chess Champion. Carlsen would have to do this first.

  If Carlsen decides to sex change, does he instantly acquire the WGM
  title?

Again the grammatical error in the question. It should be "If Carlsen decides to sex change, does she instantly acquire the WGM title?"

Certainly not! She would have to apply for the title. FIDE would have to decide if norms achieved while a man qualify for women's titles. I would suspect not which would mean that she would have to achieve the norms required as a woman.

I would add one further point. In general titles cost money. FIDE charges you if you want a title and have qualified for it. In your hypothetical situation if Carlsen wanted even the WFM title, even the WCM title, then she would have to apply and pay for the title.

I know the new regime under Dvorkovitch has talked about charging players and officials (arbiters and organizers) less and getting more money from sponsorship but I don't think this rhetoric has been changed into action yet.


Perhaps it helps if you remember the (presumed) reason for having this special move.

Originally pawns were only allowed to make single steps. This meant that pawns on adjacent files could not pass each other without running into the danger of being captured.

When the double step was introduced, pawns on adjacent files could suddenly pass each other (which would have changed the evaluation of many positions most notably in endgames). They could pass each other exactly in one case: white pawn on 5th row black pawn making double step (or equivalently black pawn on 4th row white pawn making double step).

So bottom line if you see a pawn passing your pawn without your pawn ever having a chance to capture it, it is time for en passant.


Maximum number of captures in a position

I have some records from a book published in 1969. They might have been surpassed since then, but if that is the case, I was not able to locate that information. I guess, since there is no reply after ~2 weeks, this should be better than nothing. These are records for captures by one side.
74 captures; legal position:
[Title "T. W. Marlow & William Cross, Problem 05/1967"]
[FEN "r1n1n1b1/1P1P1P1P/1N1N1N2/2RnQrRq/2pKp3/3BNQbQ/k7/4Bq2 w - - 0 1"]

Additional Source: Die Schwable Chess Problem Database Server
Edit: In response to the comment - here's a legal position without underpromotions in play, 65 captures possible.
[Title "T. W. Marlow & William Cross, Problem 05/1967"]
[FEN "k2Kb2R/1RrQnQN1/8/BqQbQqQn/8/1QbQqQNB/8/3rQq2 w - - 0 1"]

Additional Source: Die Schwable Chess Problem Database Server
Source: Guide To Fairy Chess by Anthony Dickins.


What is/are the bests poems about chess?

I like this one -

I'd be a happier man if I could play the Caro-Kann
But it seems to me when I play pawn to QB3
White gets a knight on K5, and then as sure as I'm alive
My Rook file's opened and my Queen exposed to dangers unforseen
By Nimzowitch and all that lot who think the Caro rather hot
Then if I reach the middle game my play is lifeless cold and tame
White's game is logical and bright, while nothing I can do is right.
I grow so tired of "Check", "Check"
"Check", that I become a nervous wreck
And get into a hopeless pin, allowing White an easy win.
Tell Nimzowitch it's all a plant. The opening's really Caro-Can't

- Huxley St. John-Brooks.


Game Over: Kasparov and the Machine is a decent enough documentary on the subject. The coverage does kind of imply that Kasparov was grasping at straws a bit. Like a typical World championship match there was a lot of behind the scenes tactics going on from both sides.

My feeling is that you only have to look at the ascent of Anand and other chess players who rely heavily on computers in their training and analysis to realise that, at the time of this match, there was a paradigm shift from human to computer as the dominant chess player.

Addendum:

There's a interesting tidbit in Nate Silver's “The Signal and the Noise: Why So Many Predictions Fail—But Some Don’t.” In it he describes an interview with one of the engineers who worked on Deep Blue:

  Nevertheless, there were some bugs in Deep Blue’s inventory: not many,
  but a few. Toward the end of my interview with him, [Murray] Campbell
  somewhat mischievously referred to an incident that had occurred
  toward the end of the first game in their 1997 match with Kasparov. “A
  bug occurred in the game and it may have made Kasparov misunderstand
  the capabilities of Deep Blue,” Campbell told me. “He didn’t come up
  with the theory that the move it played was a bug.” The bug had arisen
  on the forty-fourth move of their first game against Kasparov; unable
  to select a move, the program had defaulted to a last-resort fail-safe
  in which it picked a play completely at random. The bug had been
  inconsequential, coming late in the game in a position that had
  already been lost; Campbell and team repaired it the next day. “We had
  seen it once before, in a test game played earlier in 1997, and
  thought that it was fixed,” he told me. “Unfortunately there was one
  case that we had missed.” In fact, the bug was anything but
  unfortunate for Deep Blue: it was likely what allowed the computer to
  beat Kasparov. In the popular recounting of Kasparov’s match against
  Deep Blue, it was the second game in which his problems
  originated—when he had made the almost unprecedented error of
  forfeiting a position that he could probably have drawn. But what had
  inspired Kasparov to commit this mistake? His anxiety over Deep Blue’s
  forty-fourth move in the first game—the move in which the computer had
  moved its rook for no apparent purpose. Kasparov had concluded that
  the counterintuitive play must be a sign of superior intelligence. He
  had never considered that it was simply a bug.


Looks like its a stock image: the oldest source of the image I could find from 2008: http://www.grafamania.net/clipart/6201-digital-vision-dv297surreal-business.html


How do chess engines manage time when they play real games?

Possibilities:

Number of nodes
Fixed depth
Fixed time
Divide a fixed percentage of remaining time
By the complexity of the position

Let's take a quick look at Stockfish. Briefly, the file timemann.cpp calculates the minimum time allowed for a move. The default minimum time allowed is about 20 seconds.

Later, during the search it does:

 // Stop the search if only one legal move is available, or if all
 // of the available time has been used, or if we matched an easyMove
 // from the previous search and just did a fast verification.

 ...

 if (   rootMoves.size() == 1
              || Time.elapsed() > Time.optimum() * unstablePvFactor * improvingFactor / 628
              || (mainThread->easyMovePlayed = doEasyMove, doEasyMove))

If the position requires longer thinking (unstable position -
 unstablePvFactor), the engine would extend the search. How long it extend depend on calibrated parameters.

If there is an obvious move (doEasyMove), Stockfish plays it immediately.


In the line:

name:stockfish command: stockfish directory: /home/user/Desktop/stockfish-7-linux/Linux/src/.stockfish UCI on

Are you sure your exe file is called ".stockfish" and not only just "stockfish". Seems odd that you have a hidden exe file (even that it is possible)


In the United States, what are the universities and colleges with the best chess club?

The top four US college chess schools participate in the Final Four of College Chess. This year's (2015) participants were Webster University, the University of Texas at Dallas, Texas Tech University, and the University of Maryland, Baltimore County. Especially, the University of Texas at Dallas and the University of Maryland, Baltimore County, have consistently had very good results in the Pan American Intercollegiate Team Chess Championship in the last ten to fifteen years.

You can find other college chess clubs at the site of the USCF.


Where did Bobby Fischer live in New York?

Bobby Fischer lived here at Lincoln Place 560 in Brooklyn. The video shows the inside of the building. I was there in September, 2019.


The puzzle is a mate in 3 starting with a rook check. After knight to f5, there is a mate in 4 on the board, so that line is a mate in 5.

Of course one forced mate is as good as another, but if you did want to differentiate between forced mates of different length, then an argument can be made that fewer moves is better.  This is certainly how lichess does it in these puzzles, though it is certainly annoying if such a move is judged as a mistake.  Sometimes you get an admonition that your move although good is not the best and that is less annoying though arguably also incorrect.


Variation of chess where winner has to capture all pieces?

First of all, the historical rules of Shatranj include the victory condition "bare King", i.e., capturing all pieces except the King is a victory, except that the other player can capture the last piece of the first player immediately after the loss of his last piece (then, the game is drawn).

As a modern variant, there is Extinction Chess (aka Survival of the Species) where the extinction of one piece type (Knight, Bishop etc.) wins the game.


What is White's motivation to give up the Queen?

What prevents 2. Qe2, which would save the White Queen?

White's problem is the mating threats from the bishop battery and queen after Qc3. For instance:

[Title "lichess puzzle 61506"]
[FEN "rn2k3/1b1p1p1N/4pBrb/qp2P3/3P3P/pP1Q4/P4PP1/R2K1B1R b q - 2 19"]

1... Be4 2. Qe2 Qc3 3. Rb1 Qxd4+ 4. Ke1 Qc3+ 5. Kd1 Bxb1 6. Bg5 Rxg5 7. hxg5 Bxh7

and White is lots of material down and still facing mate threats (Qa1)


Is there a Open Source or Shareware Legal Move Checker Executable?

Simple problem. python-chess is a useful Python package that can do it for you easily. You will need to get a FEN, check if your move is a legal move.

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

has everything you want.


How do chess websites relay the moves for tournaments?

That depends on the tournament organisation. If the tournament organiser is happy, they provide an online PGN file which is updated everytime the player makes a move. A good digital board software can easily do that. Broadcast websites such as chess24.com simply has to poll that PGN file. Easily scaled to any number of chess boards.

Obviously, the last strategy requires cooperation. The 2018 world chess championship has no such facility. The broadcast websites has to hire someone constantly monitor the offical website (they have to pay for subscription), and relay the moves manually.

Generally, organisers especially open competition are more than happy to assist. It's a nice way for promoting their events. Chess moves don't make money.


How to connect a UCI chess engine play on FICS?

You can use icsDrone or Zippy with Winboard to connect an engine using the Winboard protocol to FICS. You can use PolyGlot as an adapter between Winboard and UCI protocols to connect your UCI engine to Winboard or icsDrone.


Is it possible to integrate an opening book and/or endgame tablebase into a chess engine? If so, how?

It's possible to integrate an opening book and/or endgame tablebase. Unfortunately there is no Java solutions, because chess engine programming is dominated by C/C++. Maybe you want to switch to C/C++? Your life will be easier.

Opening book

PolyGlot book (http://wbec-ridderkerk.nl/html/details1/PolyGlot.html)

Tablebase

Syzygy tablebase (this question has the details)

My recommendation

Unless you're an expert in programming, I don't think it's a good idea to work on Polyglot and Syzygy yourself. They're not written for beginners. GUI like Arena would be a better idea.


What are some techniques for BvN endgames?

In races when bishop can sacrifice itself for last pawn, it can stop one pawn for loooong time. Don't expect to build a knight bridge faster then the enemy king kills other side and promotes. You need rook pawn or two pawns (one to win a bishop, one to make a queen) for races. Good to have some idea about this rule.
Bad bishop itself doesn't lose often in blocked positions, bad handling of it does. Have in mind you don't need to guard all pawns. In f4 g3 h4 vs. f5 g6 h5 you must often give up on a g pawn as you need to cut the enemy king and be active. The remaining two can be protected from active swuares. Be patient. You can also give up on pawns that blocks your king. In Kc3 Bd6 d4 f4 h4  vs. Ka4 Ne6 d5 f5 h5 the f4 pawn is very good one not to care about. Guard h4 with bishop if needed, guard d4 with king and control opponent's king. The f4 don't need protection as after taking you move king to f3 and use 1.) if your opponent wants to race. Otherwise just sit and wait.
Surrounding the knight is used very often, often as indirect pawn protection. You would be surprised how easily the knight can be locked. On smaller areas killed, on bigger repetitioned to draw or just imprisoned with no way out. Imagine Bg1 Ke5 and enemy knight stupid enough to hunt pawn on b2. You win the knight after Nxb2 in few moves with Kd4.
Knight wants connected pawn formation.
Knight can stop last pawn only with king assistance, bishop can fight longer and against some pawns more in the center not far enough it can stop them forever without needing an assistance.
Good to have an idea about elementary 1:0, 2:0, 2:1 pawn ratios. For example Kf5 Nf3 g4 h5 vs. Kh6 Bc1 is draw! Knight also has big problems helping h+f pawns to promote, here rules are more difficult and big precision and patience needed. Also Kf5 Ne4 f3 g4 vs. Kh6 Bc1 g5 is easy draw as you never lose g5 pawn. When you need to protect it, you are on h6, when Nf7 is threatening, you go to g7.
If you are patient like a zen master and you can calculate like a computer, you can do miracles with bad bishop.
Have in mind wrong bishop to rook's pawn always.
On one wing both these pieces should be able to stop x+1:x majority to x being 3 and less. Not easily of course. Maybe horsie defending 3 vs 4 is lost with good corner bishop, but don't think so.


English/KID loss as white to a 2300+ player

Some elements :

9.f4 is not a wrong plan per ipse. I would prefer to finish development with 9.h3 and 10.Be3 first, but 9.f4 is correct.
11.f5 is very prematured. Your pair of pawns e4-f4 is good and controls central squares. You want to break it and attack with e4-e5 or f4-f5 only when it offers you an initiative; with Black very solid and your development unfinished, there is no attack.
The weakness of the long diagonal after 13.b3 is manageable, but the move itself is useless. It seems you are planning d3-d4 that, after f4-f5, doesn't achieve anything but new weaknesses: having relinquished the e5-square, you will never claim a Maroczy-like space advantage. Moreover, having more space on the K-side and a lag in development, you do not want to open the center. 13.Be3, 13.g4, 13.Kh1, 13.Bg5 are all more useful moves.
14.ab5 is no big deal. In the long run, only Black can benefit from the open a-file (the Bg7 is eyeing a1), but you have to play this move sooner or later anyway because otherwise your own a-pawn will become weak after an eventual ...bc4 bc4.
15.cb5 is no better than what you did; You will most probably lose at least two of the three weak pawns b3,d3,b5. After 15...Nb4 15.d4 Ned3 16.Be3 might just hold everything together, but 15...Nd4 looks simpler: 16.Bb2 Nxb5 or 16.Nxd4 cd4 17.Ne2 Bb5 and Black's minor pieces rule the the board. 15.Bf4 avoids immediate material losses: 15...Nb4 16.Bxe5 Bxe5 17.Ra7, but giving away the dark-squared bishop is very sad.
After move 16 you look just lost, one pawn falls and Black is much more active.

Note that you couldn't play a single attacking move after the pseudo-agressive f4-f5, and that Black won on the Q-side because he took time to develop (Rb8, Bd7 vs Ra1, Bc1) and enjoyed full control of dark squares (open diagonal for Bg7, Ne5, b4, d4 accessible...). The opening is not over once you have castled, the fact the game is closed shouldn't give you a false sensation of security, and you should really consider very carefully pawn moves (a4,f5,b3) when you are not fully developed. Actually, you played 7 seven consecutive pawn moves just after castling and your Rf1 even got exchanged before you could connect rooks !


Has the Soviet movie "Grandmaster" ever been translated into English?

No, there are no translations that I have found.

IMDB only lists the Russian and Polish versions. Soviet Movies Online hasn't translated it.


How can one get the best possible result against a player of very different strength?

Statistically speaking, a 600 point rating disadvantage means that you have about a 3.07% chance of winning.  If you want to improve that, your best bet is to play a position that you are familiar with.

This part of the answer might be more pertinent to a 2000 player playing a 2200 player
One way to do this is to play an opening that you know intimately.  If you have a pet line, this is the time to play it.  Especially if you've analyzed an unusual opening with a computer, this will shorten the odds.  Basically, the 3200+ rated computer will be playing your opponent for you.
Ok, that's it for opening preparation

One common suggestion is to randomize the position if you are the weaker player.  This makes a lot of sense.  Chances are that the stronger player is also better at endgames.  So you don't want to get to the endgame unless you will win easily.  I've frequently beaten lower rated players from an equal endgame or even an endgame where I'm a little worse.

In a "randomized" position, usually multiple pieces are hanging, one or both kings are weak, and most of the pieces are still on the board.  Now, unfortunately, truly good players thrive in these positions, and they will work out all the complications.  But you're probably not playing a 2600+ grandmaster, so this is still not a bad idea.  In these random positions, both players will be forced to use most of their time to make their way along the "narrow path".[1]  Once the players are deep in time pressure, anything can happen.[2]

This is NOT to say you should make bad moves.  If at any point you make inferior moves, well, the stronger opponent will probably take advantage of them.  Instead, just keep pieces on the board.  One trick you can use to complicate - when a piece is attacked, instead of moving it or defending it, just attack one of your opponent's pieces.  This is much easier said than done, but this will quickly complicate even a mundane position.

Ok, if you've made it this far, just a few more general thoughts.  The easiest way to beat a stronger player is to just get lucky.  Everyone has a bad day from time to time, you just have to be playing someone who happens to make a mistake and take advantage of it.  The key to this is to not make any terrible mistakes.  If you can stay in the game and not lose material, you can always win - even if you have a bad position.

Double check every move before you make it.  If you see a move that you think wins, spend more time than usual, don't make this move quickly.  If you're right, being behind on the clock won't really matter.  If you're wrong, you won't make an inferior move.  One saying that I've always found helpful is "never play a blunder quickly" (source unknown).

Personally, I'm not convinced that the right plan is to just complicate the position and hope.  While this is a good plan of last resort, everyone plays with the same 16 pieces.  Make solid moves, calculate everything you need to, and be inspired to play well.  Even if you lose, you'll learn far more from a well played game that you just barely lost than a game where one of the players blundered on move 12.

Lastly, some rules that have helped me against lower rated players in the past:

Don't be afraid of endgames, even if it should be drawn with best play
Similarly, don't be afraid of equal positions
A small advantage is often enough to win, but even if you are down material, swindles are often possible, so don't give up.
Finally, as a stronger player, I've had good luck in complicated positions.  As likely as it is for a stronger player to blunder, it is even more likely for the lower rated player to also blunder.

[1]: David Bronstein: "When you play against an experienced opponent who exploits all the defensive resources at his command you sometimes have to walk time and again, along the narrow path of 'the only move'."
[2]: Lev Alburt: (paraphrased from http://www.amazon.com/Chess-Rules-Thumb-Lev-Alburt/dp/1889323101) "Having 15 minutes when your opponent has 5 is worth 200 rating points."


When are pieces worth more (or less) than their nominal value?

While I don't think it's reasonable to list every noteworthy situation, here are a few more that will probably be good general guidelines.  You can use rules-of-thumb like this in order to evaluate material imbalances in your own games:

the bishop pair may be worth a rook and two pawns
the bishop pair and a pawn is worth a knight and a rook
a knight on the 6th rank is worth a rook if it cannot be traded off or chased away (and it is close to the action)
an unopposed dark square bishop is worth a rook if the opponent has played g6 and the queens are on the board
a rook on the 7th is worth an extra pawn
doubled rooks on the 7th is usually good for at least a draw
the queen may be worth two rooks if the side with the queen can start an attack.
three minor pieces may be worth a queen - take this with a large grain of salt, in every position, one side or the other usually has a decisive advantage so each case must be carefully considered
a minor piece, a rook, and a pawn are sometimes worth a queen
however, the queen with a pawn is usually stronger than two knights and a rook (for some reason, the knights just don't coordinate well, I've never had this situation in my own games)
three pawns are worth more than a piece in the endgame but much less than a piece in the middlegame (unless they are advanced in which case they restrict the opponent)

Those are all of the strange imbalances I can think of off the top of my head.  I omitted things like rook and pawn vs two pieces or knight vs bishop because those are fairly common, and those especially depend on the position.  Again, every position needs to be considered on its own, this is just to get you in the right frame of mind when you have to make a determination.


An interesting eight pieces Queen endgame

Stockfish with tablebases gives flat 0.00 so it seems highly likely to be a draw. A problem for White is they can't even take the c6 pawn with the king, 1.Kc7 Qh2+ 2.Kxc6 is a draw. So since Black can just keep giving checks and force the white king on awkward squares this seems hard to ever be winning. (especially since Black can always threaten to pick up the a3 pawn making an immediate draw)


If a player is significantly behind in time, does it mean he's bound to lose?

I don't know about statistics, but I do know that they are not "bound" to lose. It depends on the position. Is it easy to play, or is it a very sharp, tactical position? Also, is there a time-increment? Often, in classical FIDE games, there is. Based on experience, I can tell you that it can be very stressful being low on time in a long game, even if there is an increment. However, if psychological (personal) influences are ignored, it very much depends on the position and on the time-increment.


Queen's Gambit Declined: Alatortsev variation, is there a high quality resource covering this line?

Be7 avoids the QGD Exchange Variation and usually moves towards either an exchange with Bf4 or a regular QGD. If it's a regular QGD, there obviously won't be any books dedicated specifically to this variation as it will transpose to another well-known line.

The only pressing line then is the one with cxd5 and Bf4. I can't recall any books that focus specifically on this line in depth, but there have been many games played at the international level that use this variation. I would recommend exploring game databases like MegaBase and finding annotated games.


There are many plans for White here.
One is h5 and then g6 depending on whether the Knight on f5 hangs after fxg6. If instead black plays ...h6 you sack a piece on h6. Otherwise you can consider gxh7 check and attacking on the g file. Another plan is h6 and opening lines on the kingside. It seems that your pieces are not that well co-ordinated for these plans though.

All of this depends on concrete analysis. I would suggest the first move as 1.h5, with the idea h6, Qd4 and Qxg7 checkmate. If Black plays 1...f6 thwarting this idea then g6 and transposes to the ideas above. If Black plays 2...f6 then 3.fxg7. If 1...g6 then you have the option of hxg6 at any point in the future. edit eg after Rh1.


I suggest you first look at the ideas behind the systems you mentioned (e.g. Dragon, Najdorf, Sveshnikov), because in the Sicilian, black's second moves cannot be judged without looking at the intended setup, i.e. black's 4th, 5th and 6th move. These moves are often interchangeable, since white cannot play any forcing moves (apart from 3.d4, of course).

A few stray remarks:

A very common setup is putting pawns on d6 and e6. 30 years ago, this was called the Scheveningen and played by
1.e4 c5 2.Nf3 d6 (or e6) 3.d4 cxd4 4. Nxd4 Nf6 5.Nc3 e6 (or d6). Nowadays it is played by 1.e4 c5 2.Nf3 d6 3.d4 cxd4 4. Nxd4 Nf6 5.Nc3 a6 and 6....e6 in order to avoid 6.g4, and is called "the Najdorf". This is (in my opinion) unfortunate because the "real" Najdorf is defined by putting your pawn to e5, and this is a much greater difference than if e6 is played on move 5 or 6. The Scheveningen can also be reached via 1.e4 c5 2.Nf3 Nc6 (or d6) 3.d4 cxd4 4.Nxd4 Nf6 5.Nc3 d6 (or Nc6) and 6....e6, which is called the "Classical Sicilian". Of course there are Scheveningen variations where you put your knight to d7 instead of c6. You see, if you intend to play a Scheveningen style setup, you can play 2....Nc6, 2....d6, 2....e6 and maybe even 2....a6. The differences are nuances depending on which system white chooses.
If you want to play a Dragon, you can play 2....d6, 2....Nc6 or 2....g6. The move order 1.e4 c5 2.Nf3 Nc6 (or g6) 3.d4 cxd4 4.Nxd4 g6 (or Nc6)is called the "accelerated dragon", and is particularly interesting because you retain the possibility to play d5 in one move, which (for non-obvious reasons) discourages the (very dangerous) systems in which white castles long. The downside is that white can play 5.c4, which leads to a positional game with little attacking chances for black. (4....Nf6 5.Nc3 g6 is problematic because of 6.Nxc6 bxc6 7.e5.)
Variations with 2....e6 and without d6 can have independent value if the bishop is played to c5 or b4. Otherwise it's mostly a move order thing.
Finally, at almost any moment between move 4 and 6 (except if e6 or g6 have been played), it is possible to play e5. Examples are the world famous Najdorf, the Sveshnikov, the Kalashnikov, but also the (older) Boleslavsky variation.

Besides move order aspects in the open sicilian, an important factor for the third move is which Anti-Sicilians you'd rather not play against. For example:

2....d6 3.Bb5+ is different from 2....Nc6 3.Bb5. You can rule out 3.Bb5 on move 3 by playing 2...e6 or 2....g6, and forever by 2...a6.
Whatever you favourite setup against 2.c3 is, if your second move after 2.Nf3 doesn't fit, you might be forced to learn another one, since white can play 3.c3.


I'm confused by UCI Pondering and Time Control

First the GUI sends the position string with the ponder move as the last move in this string. Then the GUI sends "go ponder". This makes little sense to me, but UCI is very much a kludge. Note that the engine can actually ponder whatever move(s) it wants, but UCI tried to make it simple for basic implementations. From the protocol

ponder

start searching in pondering mode.      Do not exit the search in ponder mode, even if it's mate!       This means that the last move sent in in the position string is the ponder move.        The engine can do what it wants to do, but after a "ponderhit" command      it should execute the suggested move to ponder on. This means that the ponder
move sent by the GUI can be interpreted as a recommendation about which move
to ponder. However, if the engine decides to ponder on a different move, it
should not display any mainlines as they are likely to be misinterpreted
by the GUI because the GUI expects the engine to ponder on the suggested move.

I think the GUI simply sends "ponderhit" when it is applicable.

The main reason not to resend the position string, but to only send "ponderhit" is to ensure that the engine continues its current search in the pondered position, rather than starting a new one.

ponderhit

  the user has played the expected move. This will be sent if the engine was
  told to ponder on the same move the user has played. The engine should
  continue searching but switch from pondering to normal search.

In general, UCI tries to be "stateless", which is really it's big error IMO, as it makes everything natty. Pondering is a prime example of when the engine can really do whatever it wants (even the protocol says explicitly). The "ponderhit" command's action is determined by the "position fen ... moves" string that was already sent before the pondering began. So in that sense the GUI still sends the board state (this is completely awkward in my opinion, particularly if you want to ponder more than one move, but that's UCI for you).

Engines can/should use their own time management based on "wtime" (and/or btime/winc/binc). Again it's a bit confusing with UCI, as the GUI is supposed to be in somewhat total control (like with opening books), but then has some leeway when allowing the engine to allocate its own time (you can use "go movetime" if you want the GUI to control time management, assuming the engine complies).

You can look at a log of how a GUI communicates with an engine such as Stockfish.

GUI -> engine1: position startpos
GUI -> engine1: go wtime 100000 winc 1000 btime 100000 binc 1000
engine1 -> GUI: bestmove e2e4 ponder e7e6
GUI -> engine1: position startpos moves e2e4 e7e6
GUI -> engine1: go ponder wtime 98123 winc 1000 btime 100000 binc 1000
[user or other engine plays the expected e7e6 move]
GUI -> engine1: ponderhit
[engine keeps thinking]
engine1 -> GUI: bestmove d2d4 ponder d7d5

Or if the pondered move wasn't made, then a new "position" string is sent instead of "ponderhit".


How can one precisely sacrifice a piece for a winning attack?

If this is the best move, how does white calmly reassure himself that all of its responses are inadequate?

White doesn't see a forced advantage in every line. He sees, what he believes to be, good winning chances. To quote Spielmann in The Art of Sacrifice in Chess:

  In real sacrifices the player gives up material but is unable to calculate the consequences with accuracy; he has to rely on intuition

  What final position does white visualize that warrants the knight's goodbye?

I think you answered your own question. After 2. fxe6 bxc3 3. exf7+ white probably thought that a lead in development and 2 pawns for the piece (potentially 3 if bxc3 is played) is sufficient compensation.

White doesn't have to look further than this if they are willing to take risks and figure out the attack 2 or 3 moves at a time. If white is risk averse, then they may not even consider 2. fxe6 bxc3 3. exf7+ at all.


Since you're talking about programming, you're presumably looking for a storage scheme more compact in computer memory space than FEN. Besides going out to research how it's done in large tablebases, two possibilities come to my mind immediately.

Normal FEN

For the sake of this discussion, "normal" FEN is just a typical text string represented with 1-byte (8-bit) characters. Let's look at a simplified worst case:

r1b1k1n1/1p1p1p1p/p1p1p1p1/1n1q1b1r/R1B1P1N1/1P1P1P1P/P1P1K1P1/1N1Q1B1R w KQkq e3 999 999

This isn't a valid FEN of course, but it's an effective upper bound on our complexity. There are eight characters per rank, plus seven slashes, five spaces, and thirteen additional characters make up the remaining fields. That's 89 characters, for a total size of 712 bits.

Compressed FEN

This version is just taking the a FEN representation and using some basic observations to reduce the number of bits required to store it. Here are our observations:

The slashes are unnecessary for machine storage; each rank must simply "add to 8". So we can eliminate slashes in our internal representation.
The remaining possible characters (in the first section) are: kK qQ rR bB nN pP 12345678. Distinction between 20 characters fits in five bits, so in our simplified worst case, we have five bits times eight files times eight ranks is 320 bits for the first part.
We don't need any spaces; again they're a convenience for humans. That saves us five characters.
"Who has the move" is one bit: White or Black.
Castling availability is four bits: available/unavailable for each of KQkq.
En passant is usually unavailable, and it can occupy a lot of space (six bits to represent all squares), so let's move it to the end and make it optional: if en passant bits are present, it's available, but if it's unavailable we just terminate the representation after the move & half-move bits to save space.
For simplicity, I'm just allocating ten bits for each of the move and half-move counters. This means that games represented in this format cannot exceed 1023 moves (half-moves since the last capture or pawn advance).

Our full format looks like this (in a simplified worst case with en passant available):

<position><whose move><castling><half moves><full moves><en passant>
 320 bits  1 bit       4 bits    10 bits     10 bits     6 bits

This gives us a total size of 351 bits in our impossible worst case, a little less than half the size of our starting point.

µFEN

If we abandon FEN altogether for the meat of the representation, we can slim it down a little further. Consider a single arbitrary square. That square can be empty, or it can have a piece on it. If it has a piece, it may be either white or black, and it may be a King, Queen, Rook, Bishop, Knight, or Pawn. That's a total of thirteen different states, which we can represent in four bits; something like this:

0000: empty square
0001: White Pawn
0010: White Knight
0011: White Bishop
0100: White Rook
0101: White Queen
0110: White King
0111: unused
1000: unused
1001: Black Pawn
1010: Black Knight
1011: Black Bishop
1100: Black Rook
1101: Black Queen
1110: Black King
1111: unused

Obviously there are some unused "partial bits", so this scheme could almost certainly be improved further by someone with more knowledge of compression techniques, or simply a more careful mapping of the different states. Also in practice, this might be larger than the Compressed FEN described above, since there's no compression of contiguous blank spaces. However, it does represent the whole board in a constant 256 bits (4 bits * 64 squares), which is a 20% improvement in the worst cases.

For simplicity, we'll just tag on the latter half of the Compressed FEN to complete the representation. So the format looks like this:

<position><whose move><castling><half moves><full moves><en passant>
 256 bits  1 bit       4 bits    10 bits     10 bits     6 bits

That gives us a worst-case space requirement of 287 bits. Not too bad!

Note 1: Remember, this is all just a worst-case analysis because I have a computer science background. Standard FEN usually performs much better than I have described it, since normal positions aren't the everyone-on-the-white-squares scenario I've used for comparisons here. So the percent improvements are likely a little lower than I've actually represented, but the trend probably still holds, at least for the compressed FEN representation. I'd be very interested if someone wanted to do a probabilistic average-case analysis for standard FEN (and by extension, the compressed version proposed above)!

Note 2: Remember that the speed tradeoffs for dealing with compressed formats may or may not be worth it for your applications! Depending on what language you're using and the level of control you have over individual bits, you may find that simple FEN is significantly faster to use, even if it requires more space!

Note 3: If you wanted to add a "check/checkmate/no-check" indicator to either of the new proposed notations, it's an extra two bits to represent the three additional states. Just toss it in before the en passant indicator.


Is it possible for a move to be recomended by engines but rejected by professional human players?

I see three situations, where something like you describe could happen:

wild tactical positions with open king, where moves have to be very precise and many humans might be too scared to enter such position
Many composed studies feature surprising moves that could be rejected by humans. For instance studies in which you give up all your material except for say a bishop with which you mate somehow. In most positions you can't win with a bishop only, so lines leading to such positions would not be considered usually.
some of the more tricky endgames feature very unnatural/inhuman moves that would be rejected by human players. One example are the computer lines after move 67 in game 6 of the last WC match Carlsen-Caruana. Some quotes regarding the winning lines suggested by computers:

Svidler:

  Even when I saw what the machine suggested was winning there I honestly don't think it was humanly possible to find it on the 10 minutes that Fabi had, and it's incredibly weird how the position is conceptually lost after Kg6.

Kasparov:

  The computer shows Black wins with 68..Bh4 here. But had Caruana played the incredible 69.Bd5 Ne2 70.Bf3 Ng1!! they would request metal detectors immediately! No human can willingly trap his own knight like that.

Svidler:

  A move that a human is more or less incapable of making

Grischuk:

  I would never even dream about Bh4

Carlsen:

  I’m not going to disagree with the computer, I just don’t understand it!


Engine with emphasis on strategic/positional analysis

Chess engine is just a tool, your question is like asking which calculator your should use for learning mathematics.

An engine will just give you a score and a computer line, it tells you what you should play but it doesn't tell you what you shouldn't do.

You'll need to work hard, and use the engine to aid your analysis. Consider to pay for a human chess coach.


Is it possible Alpha Zero will eventually solve chess?

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


Android 32 bits? stockfish-10armv7

Android 64 bits? stockfish-10arm64v8 and stockfish-10-arm64-pgo

stockfish-10-arm64-pgo is faster but also with larger file


This is not a blunder, expected behaviour from the engine. Everything worked as intended. Try to copy the FEN string out, and you'll know.

Although the position looked winning, White didn't have enough moves to force checkmate before the 50 moves rule. Stockfish, knowing the position was a dead draw immediately asked for simplification.

The position you had is 100% equal, there was no way to win it. It's a draw. What Stockfish did was not wrong.

If the Tarrasch program didn't send out the 50 moves counter to Stockfish, you'd never get the problem on Tarrasch. If that was the case, it was an error in Tarrasch because the 50 move counter is part of the game.

Solution?

Setup a new board with the same position but reset the 50 moves counter.


Is there any software that can be used for positional chess training?

Perhaps an engine something like Chess Position Trainer, depending upon your requirements (and system).
     There is some potential for an unexpected learning curve, at least within version 5.04.
     That being said, it is noted as working in both Windows & Linux.

Komodo 8 also gets some recommendation.

Chessimo has at least one detractor, who showed a preference for Convekta, this latter offering both downloadable and online games (their online play permits Windows, iOS, Android, & Web Interface).

Basic Positional Ideas "...is a supplementary program [that] can only be run if [sic] Fritz 8...". The description indicates that the program is for learning "...[how] to achieve the desired position on your board...".
     The use of Fritz indicates that it should run on Windows, but that you might need Wine in order to run it within a Linux environment.


What chess *scoring* alternatives exist?

I think the only alternative would be in match play or comparing a player's score across multiple games against another player or players.

For example, in a 12 game match between two players:

(+3 =8 -1) would be worse than (+5 =6 -1)

even though the first player won both matches.

Scoring by material count or number of moves played would not be beneficial. If the number of moves mattered, with shorter games being considered crushing defeats, players would just refuse to resign and drag the game out. On the other hand, I can lose in two moves without losing any pieces.

The only thing that seems to make sense is to compare score across multiple games against an opponent or field of opponents. You may have a better comparison considering a GM's total score in a tournament with many rounds. In a 9 round tournament, a 9.0 score would be crushing the competition. Winning the tournament with 6.5 would be less of an accomplishment.


Can you recommend a dynamic, concrete, or easy-to-play line against the London System?

According to modern theory, playing the QGD as if you were white is the best option.  (That is, of course, just to sell more useless books.)

I play an early Bd6 to challenge this system, but the problem I experience is when they don't trade the bishops.

The logical plan is to play the KID.  The bishop will be "biting on granite."  When the time is right, pushing the e pawn will gain tempos on the Bf4 and Nf3, and since this system mostly develops the Bd3, a fork is possible.
Another popular theory is to exchange on d4 and plan for a minority attack.

None of these seem dangerous, but you can use their development system to expect certain moves.  You know that they won't be attacking with c4 and you know that they will place a knight on f3 (and later on e5.)  An early Bg4 to avoid the bad bishop, and, since they aren't attacking your center, this bishop won't need to be protecting b7.

Also possible is to develop your bishop before establishing the triangle formation.

These won't prevent long games, but it may provide you with positions that you are more comfortable with.


The parameters I can think of:

Number of

Chess club members
FIDE rated players
FIDE titled players
Grandmasters
Female players
Tournaments
Seminars / lectures

I'm not sure how to convert these parameters into a final score, nevertheless I'm curious how the list of best chess cities would look like. I would expect Moscow to be clear number one (many resident grandmasters, many tournaments). I'm also wondering how good Saint-Louis would score.


Here are some mistakes you should avoid while playing the so-called Jobava Attack.

3...c5 is one good answer, and as you can see 4.Nb5 is not working here.

The video below also shows many tactics in the middlegame, after other continuations like 3...c6 and 3...e6.

After 14...Rfc8?! 15.Nf5 the best response is taking the knight and accepting a shattered pawn structure. Otherwise white is much better (+1.3 in the least: https://lichess.org/analysis/standard/r1r3k1/3bqppp/p3pn2/np1p2B1/3P4/P1NB3P/1PPQ1PP1/3RR1K1_b_-_-_1_17)

      [StartPly "5"]

      [FEN ""]
      1. d4 d5 2. Nc3 Nf6 3. Bf4 c5 4. e3 (4. Nb5? Qa5+
5. Nc3 cxd4 6. Qxd4 Nc6 7. Qa4 Qxa4 8. Nxa4 Nb4 (8...e5)) cxd4
5. exd4 a6 6. Bd3 Nc6 7. Nge2 e6 8. Qd2 b5 9. O-O Be7 10. a3 Bd7 11. h3 O-O 12. Rfe1 Na5 13. Rad1 Qb6 14. Ng3 Rfc8?! (14... Rfe8!) 15. Nf5 Qd8? (15...exf5) 16.Nxe7+ Qxe7 17.Bg5

You can find a more detailed video explanation here:

https://youtu.be/5joSsNpJ9qw

Related games:

https://lichess.org/OfUGrtY6

http://www.chessgames.com/perl/chessgame?gid=1838817

http://www.chessgames.com/perl/chessgame?gid=1857787


How do I identify strong pieces?

Read books on pawn structures (Kmoch, Soltis, Baburin etc.)  Pieces are strong/weak entirely based on the landscape that gets carved out on the board through hostile negotiations that the purists call the Opening. Treacherous valleys, open plains and rocky crevices ... all of
these get created by different pawn structures. Know the structures
and you'll automatically see which pieces are going to become strong
and weak well before they get to that state.
Consider picking up some of the lighter and rudimentary books on strategy like Michael Stean's Simple Chess or Todd Barwick's Chess Strategy Workbook (which has a fantastic section description on what makes a piece strong or weak)

How do I produce (make my pieces strong, my opponent's pieces weak) in my own games?

Supplement your reading (see section above) with studying annotated Master Games to find these patterns and learn how the big boys execute on the typical plans associated with these sorts of strong-or-weak pieces. You'll slowly start to subconsciously (or consciously) emulate these ideas.
Review your slow time-control games with a stronger player to go over opportunities where you missed opportunities to strengthen or weaken a piece. After tactical safety is established, you should always be looking to improve your pieces (or diminish the usefulness of your opponent's pieces). Sometimes just doing this is more practical (with a clock running) than some fanciful deep strategic idea that is outside most mortal club player's wheelhouses (that the more advanced books notoriously confuse people with)


Is the Scandinavian Defense a good opening for beginners?

The opening is playable at all levels, though quite rare in grandmaster play. Here is what chess.com says on the opening:

  Although the Scandinavian is not played much by grandmasters, it is generally considered to be an opening that is easy to learn and worth trying out for beginners and club level players.

I believe the appeal of the opening is that it is quite conceptual. After 3...Qa5, the mainline, none of the pieces are attacking each other, meaning that there aren't many tactics or much theory in the early part of the game.

[FEN ""]

1. e4 d5 2. exd5 Qxd5 3. Nc3 Qa5 4.d4 c6 {Creating a bolt hole for the queen if she is attacked.} 5.Nf3 Nf6 6.Bc4 Bf5 {Developing the bishop before locking it outside of the pawn chain.} 7.Bd2 e6 {Black will develop the dark square bishop, castle kingside, then play for central pawn breaks.}

Both sides have developed simply and logically.

Edit: Others have stated the Scandinavian is not testing at the high level. If you wish to employ different openings later on, the caro-kann and slav-defense have good reputations and similar pawn structures to the Scandinavian.


Different sites will have different rating systems, even for games!

So, for tactical puzzles, basically every site works in a completely different manner. Also, I don't know about chess.com, but in chesstempo, different settings will also result in different ratings, as the kind of puzzles will be different, and the balance is not perfectly achieved.


Recommendation of a book for learning strategic concepts

There are two new and well received books in that direction:

Winning Chess Manoeuvres
Chess Structures

At least the latter contains 50 exercises as well.

Strategic Play by Aagaard is very close to your specifications, it contains a lot of exercises and is pretty much about 'the long plan'. Unfortunately it's extremely difficult. (I gave my book away to a friend, who is close to his last GM-norm).

Positional Play is much easier, but still tough for an 1800 player. And of course the focus is more on correct piece placement and the like.

And Techniques of Positional Play is supposed to be quite good as well.


Why is Tal talking about 10. Qf7 when 10.... N5f6 is possible?

You made a mistake when transcribing move 7. It is 7. Qh5+, not 7. Qf3+. Move 10 is then Qh5f7, which is not blocked by the Nf6.
[FEN ""]

1. e4 Nf6 2. e5 Nd5 3. d4 d6 4. Nf3 dxe5 5. Nxe5 Nd7 6. Nxf7 Kxf7 7. Qh5+ Ke6 8. c4 N5f6 9. d5+ Kd6 10. Qf7 Ne5


Why is 5. Nc3 preferred over 5. f3 in the Open Sicilian?

The move 5.f3 is an interesting one and worth a try for two reasons:

Avoiding heavy theory.
Tricking some Najdorf or Dragon players who are not keen to play the Maroczy bind with c4.

However, Black has a few ways to respond. One response seems very tricky by directly exploiting the weakness created by f3 (and avoiding the Maroczy bind).

[FEN ""]

1.e4 c5 2.Nf3 d6 3.d4 cxd4 4.Nxd4 Nf6 5.f3 e5 6.Nb3 a5!? 7.c4? (7.Bb5 {is better}) Nxe4! 8.fxe4 Qh4+ 9.Kd2 a4 {and Black wins back the piece with some advantage}

Black seems to be fine by playing e5 and d5, without pushing further to d4 as played recently by Giri, Nakamura, Areshchenko.

[fen ""]

1. e4 c5 2. Nf3 d6 3.d4 cxd4 4.Nxd4 Nf6 5.f3 e5 6. Nb3 d5 7.Bg5 Be6 8.Bxf6 gxf6 9.exd5 Qxd5 10.Qxd5 Bxd5 {and the pair of bishops offsets the pawn weaknesses.}

Update: If following the good arguments of @Scounged, Black is not afraid to enter the Maroczy bind, there is a favorable version. Black plays 5...Nc6 and if White continues by 6.c4 Black replies with 6...Qb6 disrupting White's play, followed by g6. Here is an illustrative game:

[fen ""]
[title "D'Amore, Carlo (2456) vs. Sutovsky, Emil (2664), EU-chT, 2001"]

1. e4 c5 2. Nf3 d6 3.d4 cxd4 4.Nxd4 Nf6 5.f3 Nc6 6.c4 Qb6 7.Nc2 g6 8.Nc3 Bg7 9.Qd3 (9.Rb1 {is probably more promising for White but there is a fun variation} 9...Ng4!? 10.Qd2! (10.fxg4 Bxc3) Bxc3 11. Qxc3 Qf2 12.Kd1 O-O) 9...Nd7 10.Nd5 Qd8 11.Be2 Nc5 12.Qa3 f5! 13.exf5? (13.O-O) Bxf5 14.Nde3 Qb6 15.Nxf5 gxf5 16.Rb1 Nd4 17.Nxd4 Bxd4 18.Be3 Ne6 19.Bxd4 Nxd4 20.Qa4+ Kf7 21.c5 Qxc5 22.Qc4+ Qxc4 23.Bxc4+ Kf6 24.Kf2 Rac8 25.Bd3 e5 26.g4 fxg4 27.fxg4 d5 28.Rbd1 h5 29.g5+ Kxg5 30.Rhg1+ Kf4 31.Rg7 Rhf8 32.Bg6 Kg5+ 0-1


Computer being right and human being wrong

This has definitely happened in endgames, e.g.:

Queen and a minor piece versus two rooks: this is usually a draw for a knight and a win for a bishop, although the win takes up to eighty-five moves. The best method of defense is to double the rooks on the third rank with the opposing king on the other side and keep the king behind the rooks. This case with a bishop and queen versus rooks is unusual in that such a small material advantage forces a win. It was thought to be a draw by human analysis, but computer analysis revealed a long forced win (Müller & Lamprecht 2001:404), (Nunn 2002a:328–29,367,372).

It also happens earlier during the middlegame, although this will depend on the time the human spends analyzing. It's a lot easier for the human to find the winning line if they know there's a way to "break the fortress".
Example (39 minutes in):
[FEN "1q4rr/5p2/kpb2b2/p1p1pP2/P1PpP1pN/1P1P2P1/4QBN1/1K4R1 w - - 0 1"]

(Black to play)
Black is up the exchange, but the position is completely locked. Black could sacrifice an exchange on h4, but White has the g4-pawn well-covered and trades will only help White draw, since Black's c6-bishop is never penetrating White's position and it'd be an OCB endgame as well. Draw?
In fairness to Nakamura, he didn't actually say it was a draw (he was playing against Komodo, after all), but you can see his reaction to Komodo's next move.


As white is a pawn down without compensation, piece exchanges should be avoided. White's only practical chance is a king side attack.  Maybe Bc4, with the plan of Bc4-a2, c2-c4, Ba2-b1. Along with Qh5 and/or Qc2 plus g2-g4. Its slow and black can defend, but what else can white try?


This is the Sveshnikov Variation of the Sicilian. It is a fairly popular line even at the highest level.

You are right, that 6. Ndb5 is the critical move. The game usually continues from there: 6. ... d6 7. Bg5 a6 8. Na3 b5

Black has somewhat weakened d5 and the pawn on d6 is weak, but in exchange he has expanded on the queenside and is threatening a fork on b4.


Now I haven't played the Tarrasch, but I am considering it, as an alternative to the exchange variation, and this is what I've discovered in my limited research.

The main purpose is to support the pawn chain, if Black continues with 3. ... Nf6, as the c3 square is available for a pawn to support d4. Additionally, as a bonus, it avoids the Winawer variation of the French, without playing the advanced or exchange variations, which are easier for black at higher levels.

While it does block in the Queen's Bishop, other than the classical lines, 1. e4 e6 2.d4 d5 3. Nc3 Nf6 4. Bg5, it's not uncommon for the Queen Bishop to remain undeveloped for most of the opening.

As for which line is the sharpest, a lot depends on black's responses.


Can anyone find any redeeming qualities in "The Vulture"?

3...Ne4 is kind of pointless. The idea is to play Nd6 controlling e4 and attacking the c4 pawn. The only other options are Nf6 losing a tempo or f5 in a weird Dutch-like position. White is maintaining an advantage after 3...Nd6 4.e4 though.

It avoids theory I guess.


The obvious tactic is

1) ... a6 2) Na3 Nxd4 3) cxN Qxd4 4) QxQ BxQ and you are forking the two rooks on a1 and g1

Disclaimer: I haven't checked this with an engine but it would be my first thought during the game. The engine may find a hole in this


Did Richard Teichmann fail to take his "bishop pair" idea to its logical conclusion?

I'm not going to claim in a black-and-white way that your idea of 20...Bf8 is strictly inferior to Teichmann's 20...Kf8 in objective terms, but I can think of two solid reasons not to play into the resulting 20...Bf8 21.Bxf6 gxf6:

Contrary to your general operating premise that two bishops are superior to two knights, in this position White's knights are fantastic, and in particular, Black's poor pawn structure is such that the knights have wonderful outposts to camp in, as well as weak pawns to target down the road. Really, I'd take either of these knights over either bishop in this situation, so much so that if I were playing Black from this point on, I think I'd feel compelled to trade one of the bishops for a knight at some point anyway, and so I'd rather have done so without having compromised my pawn structure in this way.
White's position in this line is much easier to play. White has no structural weaknesses, while Black has targets in her structure. The knights have natural squares screaming out for occupation, while the light-square bishop is especially hemmed in, not least because of the isolated d5 pawn.

It's tough to give detailed analysis of variations without inline commenting, so I'll just illustrate what I mean with a single line. After, say, 22.g4 to make luft for the king and grab space on the kingside, even a seemingly productive move like 22...Rc2?! for Black doesn't actually lead anywhere, basically because of the pluses indicated above. For instance, after 23.Ned4 Black can't follow up with 23...Rxb2?, because after 24.Rc1! White will gain a big edge while Black looks after her inferior pieces: e.g. 24...a5 (forced, as otherwise the b7 bishop will be embarrassed) 25.Rc7 Ba6 26.Ra7 Bc8 27.Rxa5 and White has a huge plus. Even if it doesn't look that way at first glance, if one plays around with this position a bit, it's much easier to find good moves for White, and it's actually quite difficult to bring the black pieces (including the king) into play without running into trouble.

[fen "2r3k1/1b2bppp/p4n2/1p1p1NB1/8/4P3/PP2NPPP/3R2K1 b - - 0 1"]

1...Bf8 2.Bxf6 gxf6 3.g4 Rc2?! 4.Ned4 Rxb2? 5.Rc1! a5 6.Rc7 Ba6 7.Ra7 Bc8 8.Rxa5

Again, that's just one illustrative line, and certainly one in which I picked a mistaken idea for Black for effect. But the point is, if Black can't effectively make an active threat like the one indicated without facing such a harsh backlash, then it's not a position in which Black has much of anything to play for, and instead is one through which Black must suffer and just hope to hold on. To me, that's reason enough not to go in for this option over 20...Kf8.


I'm an FM so I guess I'm experienced. For Black's POV, the 12...e6 variation you gave is the best way to play. It pretty much stops White's attack and Black's just up a piece. If he really wanted to Black could have also gone for 11...Ke8 followed by ...e6. In any case, playing with ...e6 is the way to go since it covers up all Black's weak light squares.

For you, I'd recommend not going for 3.Qxd4 (it's rather dubious). If you want to go for this kind of setup, consider playing 2.Nf3 and after 2...d6, 3.d4 cxd4 4.Qxd4. Of course you couldn't go this after 2...Nc6 though. If you still want to play 3.Qxd4, consider 4.Qe3 followed by 5.c4. It gives you a bind in the centre at least.

After 9...b4 in the game, you should have played 10.Nd5. You're a bit worse, but at least the game is close to equal. After 10.Bxf7, I think you played well to get compensation. I wouldn't recommend playing safe AFTER 10.Bxf7, since you need to attack to make up for being down a piece.


What was the question asked to Magnus Carlsen which he refused to translate?

According to Tarjei Svensen, the question was "Kasparov compared you to Harry Potter this week, Stensbøl compared you to Petter Northug, which comparison do you prefer?" to which he replied that he preferred to be compared to real people, therefore Northug. See this Twitter conversation.


The easiest way to visualize the board is to practice!  I know that sounds trite, but there aren't really all that many shortcuts.  Go over games in magazines.  Start from one of the positions given as an image and then "make" as many moves as you can in your head.  Try to see the position and look for the threats and ideas of each move.  If you can only make one move, that's fine - it's a good start.

Similarly, you can use a physical board when you're going over a game.  Play out the moves on the board and start to learn the squares by name as opposed to figuring out which square is which each time.  That's probably the first step.  After you know the "names" of the squares, the rest will start to fall into place.


You are right, this is nonsense. From the FIDE laws of chess, article 5:

  The game is drawn when the player to move has no legal move and his king is not in check. The game is said to end in ‘stalemate’.

If capturing en passant is possible, it is a legal move so if it is the only option, Black is required to play the move. (Or not to move at all and lose through the clock.)


The chess.com engine didn’t show a checkmate

As White's previous move was pawn on h2 to h4 then pawn g4xh3 is a legal en passant capture.

For more info - see Rule 3.7.d of the laws of chess


What to choose to play as black if you play King's Indian Attack as white?

The King's Indian Attack isn't called the King's Indian Attack for nothing; it's White's version of the King's Indian Defense which is an opening for Black, characterized by the moves 1. d4 Nf6 2. c4 g6, and Black intends to follow up with Bg7, d6, castling kingside and either c5 or e5. So you should get a structure you're familiar with, although the precise moves may be different.

You can't really play the KID against 1. e4, so you'd have to opt for the Modern Defense, or the Pirc you already mentioned. If you're attracted to the setup with g6 and Bg7, the Sicilian Dragon would also be an option.

  but what I have noticed recently is that with white my score is much better that as black - with white I have 40 victories more than loses, but with black I have only 8 victories more than losses.

Depending on the strength of your opponents and the number of games you play, this can be quite normal. By moving first, White has a slight advantage and (at all levels of play) this implies players score better with White than with Black. I wouldn't really worry about it for now.


I think you're misunderstanding something here based on the way you formulated your question.  Multiplying the blockers by the magic and the shifting does not give you the attack set.  What it gives you is an index by which you can lookup the attack set in a pre-computed array.  The shifted product is a key, not a bitboard as you displayed it
It is possible (and desireable) for multiple blocker sets to result in the same index and therefore have the same attack map.  Consider a rook on A1.  The attack set will be the same if there is a blocker on B1, blockers on B1 and C1, blockers on B1 and C1 and D1.
As for how long it takes to generate the magics themselves, that depends on your hardware and on the speed of your algorithm.  I would say that only being able to test a thousand in a few seconds indicates a serious performance issue in your code.  I feel like stockfish claims to be able to generate them all in a second or so.
Finally, the benefit of findind a "better" magic is what you said.  It reduces the size of the pre-computed array.  Lowering the memory footprint of an engine makes it more efficient in terms of cpu cache hits vs memory lookups.


In the Slav, after 1. d4 d5 2. c4 c6 3. Nf3 Nf6, what are all the differences between 4. Qc2 and 4. Qb3?

After quickly looking at the differences, I think Qb3 is more suited if you want to fianchetto.

The queen puts pressure on b7 and d5 and combines nicely with a fianchettoed king bishop.

If the queen is on c2 black often plays g6, planning to fianchetto and also play Bf5 with tempo.

Both moves are equaly popular. The choice is yours!


As soon as triangulation becomes possible, which occurs as soon as anyone makes a move that allows a piece besides a knight to advance to the third rank, you cannot determine with certainty who has the move.
For example, with a pawn on e3, it could be Black to move because White just played their first move, or it could be White to move with a sequence like this:
[FEN ""]
1. e3 Nf6 2. Bc4 Ng8 3. Be2 Nf6 4. Bf1 Ng8 *

If any piece or pawn is captured (except the queens!) that also means you cannot determine who is to move:
[FEN ""]
1. Nc3 (1. Na3 Nc6 2. Nc4 Rb8 3. Nb6 Nb4 4. Na8 Rxa8 5. Nf3 Na6 6. Ng1 Nb8) 1...Nc6 2. Nd5 Nb8 3. Nb4 Nc6 4. Na6 Nb4 5. Nb8 Rxb8 6. Nf3 Ra8 7. Ng1 Na6 8. Nf3 Nb8 9. Ng1 *

But if no pawn has moved (or if the only pawn moves are a3/a6/h3/h6) and nothing has been captured (with the exception of the queens) then you can tell from the board position who has the move. The knights can never lose a tempo, and the rooks cannot triangulate if they don't have enough room to move more than one square at a time. The king also cannot triangulate if the only square available is the queen's square.


What is the strongest chess engine working on Arduino (Atmega328)?

Not every chess engine works on Arduino as it doesn't run a conventional *nix operating system.

There's a list of chess engines that do work here:

http://chessprogramming.wikispaces.com/Arduino

Updated url from Fabian's comment:

https://www.chessprogramming.org/Arduino#Chess_Programs


Unable to understand why N.McDonald - A. Stromer (1991) is a draw and not a win

I suspect he means wins the pawn, as opposed to the game. A lone knight is insufficient material to mate, and black would have to cooperate to be mated with the rook vs. knight.


Has the performance of physical electronic chess sets increased similarly to the performance of software based implementations over the years?

There is are basically two features you can look at to decide whether a board computer will be faster: Elo (i.e. playing strength) and processor speed.

The stronger the maximal playing strength the faster it should be (on comparable levels). Lexibook Chessman Elite should be around 1800, whereas Systema Jupiter Deluxe plays at appr. 1400 Elo.

I couldn't find the chip speed for Systema Jupiter, but Lexibook has a 2 MHz chip. On this list you can look for something maybe a little faster and a little stronger, though at some point you may have to worry whether the weaker levels are still weak enough.

I would say that Lexibook, being 400 points stronger, should be comfortably faster than Systema Jupiter.


Is there a proper way to indicate "stalemate" on your scoresheet?

On your scoresheet you are required to record the result which 99.99% of the time will be one of 1-0, 0-1, ½-½. In the very rare cases when it is not one of those somebody will almost certainly be appealing the arbiter's / organizer's decision ;-).

You are not required to put how that result was achieved, e.g. flag dropped, resigned, defaulted, draw by 3-fold repetition, draw by 5-fold repetition, draw by 50 move rule, draw by 75 move rule (I actually got to rule that in a junior competition a few weeks ago - a real pain in the backside having to count up to 75 ;-) ), successful draw claim under appendix G in a quickplay finish that my opponent wasn't trying to win, successful draw claim under appendix G in a quickplay finish that my opponent couldn't win by normal means, checkmate, stalemate, etc. Note that I believe some national federations still allow adjudication but FIDE does not.

You get the picture! It would get a bit silly. Of course you are free to record that if you want. Just that not being a requirement there is no "approved" way for doing this.


To me, it looks like your plan is to move your king forward to d6. After he takes your pawn, you play Kd6 keeping opposition and blocking the pawn advancement with the Knight on c7. Looks dead drawn after that.

[Fen "8/6k1/1p2Kn1p/7P/1P6/5B2/8/8 b KQkq - 0 1"]

1... Ne8 2. Kd7 Kf7 3. Kc6 Ke6 4. Kxb6 Kd6 5. Ka5 Nc7

[Fen "8/2n5/3k3p/K6P/1P6/5B2/8/8 w - - 3 6"]


Why did the (Black) computer play 9. ... Ke7 here?

The answer to your question is that there is no good reason to play this move. I plugged the position before Ke7 into StockFish on lichess. At depth 27, StockFish gives the position a +6.3 for white. After Ke7, the analysis jumps to +10.8 for white. Ke7 is a blunder.

StockFish aside, the only thing that this move does do is remove the pin placed by the white Bishop on the f-pawn. A better move to accomplish this goal (and indeed the one that StockFish suggests in this position) is a6.

This computer program is set to play generally poor moves - the 800 rating of the computer indicates that the computer is almost playing randomly - playing any better would increase its rating.

Note: I analyzed the position with SF (and mentally) because I didn't just want to tell the OP that the computer was playing poorly [it is, but that wouldn't make a good stand-alone answer IMO].


What's the rationale behind chess engines conditionally allowing threefold repetitions when assigning a draw score?

It says that “to wait for the second repetition one has its pros and cons.” So, what exactly are the pros and cons? I couldn't find an explanation as to why top chess engines like Stockfish and Ethereal do this.

My discussion will be technical, so let's make it as simple as possible. Firstly, let's make be clear about this:

  If the first occurrence of position p is not strictly after the root node then they don't assign a draw score to the twofold repetition.

Why would an engine do that? Let's consider two scenarios where we have three-fold repetition during the search. Let's assume we are on move 30th, and the engine is thinking at move 40th.

The position repeated and played on the board, for example, the position occurred on move 24th and 26th.
The position never actually played on the board, but it is part of the search. The position occurred at move 35th. (IMPORTANT - only a single repetition)

Scenario 1

In the first scenario, it's a repetition that we all understand. In your code example:

++reps == 2

So, if a position repeated twice earlier in the game before the root (root == current board position), it's a three-fold repetition. Very simple.

Scenario 2

What about the second scenario? You have the identical position on move 35th, and the same position come back on move 40th. Thus, it's reasonable to assume if you search further you will encounter the position again (for the third repetition). For example, move 45th.

Your code example:

i > board->numMoves - height

  So, what exactly are the pros and cons?

Pros: search quicker and deeper

Cons: you assume the same position would occur again later in the search (e.g. move 45th), which is not always true

  I couldn't find an explanation as to why top chess engines like Stockfish and Ethereal do this.

Search quicker and deeper. Common optimization in modern chess programming.


How this game is denoted as French Advanced Variation?

I apologize for posting a comment as an answer, but this is the only way for me to include diagrams, which I find helpful.

You have entered Advanced French defense by transposition.

After 1.e4 d5 2. e5 e6 3.d4 we get the following position:

[StartFlipped "0"]
[fen "rnbqkbnr/ppp2ppp/4p3/3pP3/3P4/8/PPP2PPP/RNBQKBNR b KQkq - 0 3"]

The usual way of reaching the above position is with 1.e4 e6 2. d4 d5 3. e5

[StartFlipped "0"]
[fen "rnbqkbnr/ppp2ppp/4p3/3pP3/3P4/8/PPP2PPP/RNBQKBNR b KQkq - 0 3"]

Lichess was smart enough to figure this out.


What are the benefits of having a space advantage in a closed position?

Michael Stean, in his "Simple chess" introduced the idea of the "capacity" of a given Pawn structure. How many pieces can live inside it without getting in each others way. If your opponents pawns do not have enough capacity for his pieces, he will have difficulty manoeuvering them to defend. This introduces the "principle of two weaknesses" You inflict two weaknesses in your opponents structure. You can switch your attack from one to the other faster than they can switch their defence. The nature of the weaknesses can be whatever is in the position. A vulnerable King, a weak Pawn, a desirable exchange, establishing control of a file...It can be an end in itself or a stepping stone to something else. Search for "two weaknesses" on Youtube.


In Caro-Kann Defense, what are the differences between 3. Nc3 and 3. Nd2?

3.Nc3 allows White to play the Two Knights Attack with 2.Nf3. It does block the c-pawn, though, so Black can play 3...g6, the Gurgenidze System, because White cannot protect the d-pawn with the c-pawn.

There is also the rarely played Gurgenidze Counter Attack 3...b5. A very dubious line that can be stopped easily with a3.

3.Nd2 tries to avoid these lines, but it makes the Two Knights Attack impossible, a line that is very popular nowadays. It also blocks the view of White's dark-squared bishop, so Black can develop their kingside knight to h6 if they want.


What is the standard way to calculate scores in team tournaments?

I think the standard way to treat a team tournament is like a normal tournament, only with teams instead of players.

So there is swiss system pairing if there are too many teams for a round robin. A win gives you 1 point, a draw 1/2 and a loss 0. Sometimes that 2 points for a win, 1 for a draw and 0 for a loss, but that's equivalent.

The number of board points, i.e. the sum of points each player of a team has made, is usually used as a tie-breaker.

It used to be the case that the olympiad had board points as scoring system. But that doesn't make much sense for a team event and also leads to pretty boring tournaments, so it was changed in 2008.