In the shown position, should I push pawns or trade material?

Should I push pawns or trade material?

Good question. You are winning either way but it's always more relaxing to win the easy way rather than the hard way.
The key in these sorts of endgames is how active the pieces are. Black's knight on h6 is terrible. It is doing nothing really useful and has no prospects unless it moves somewhere else. White's rook on e5 is very active. The rook on d1 is passive, albeit it is doing an important job of trying to defend the d4 pawn. The d4 pawn is undefendable so white would do well to jettison it in return for activity. White's next move should probably be Rde1 almost regardless of what black does. The two black rooks are attacking the white pawn and so are reasonably active.
If you were to start immediately pushing the queenside pawns then the obvious first move would be c5 because the d4 pawn is pinned. The idea would be to take with the c pawn and have a protected passed pawn but I don't think it is that good move. There is no rush. White's d pawn is yours whenever you want it. Try and look for better ideas.
The one really annoying thing about white's position is that rook on e5. So, for me the best move is Nf7 kicking it away. It also starts the process of moving the knight to a really good square. To my eye e4 looks like an excellent square for the knight. That is really going to annoy white and make life difficult. I would aim to get my knight there first and then think of taking the free pawn on d4.
Maybe something like this:
[fen "3r4/ppp4p/5k1n/3rRp2/3P1P1P/P6P/1P4K1/3R4 b - - 0 1"]

1...Nf7 2. Re3 (2. Rxd5 {alternatively} Rxd5 3. Kf3 c5 4. Ke3 Nd6 {Nc4+ is calling me} 5. b3 {stopping that idea} cxd4+ {Nb5 was another way of winning the pawn} 6. Rxd4 Rxd4 7. Kxd4 Nb5+ 8. Kc5 Nc7 {Nxa3 is also good} 9. Kd6 Ne6 10. b4 Nxf4 11. Kc7 Nxh3 {and the f pawn will queen long before white can get anywhere near queening on the queenside}) Nd6 3. Rc3 c6 4. b4 Ne4 (4...Nb5 5. Rcd3 Rxd4 6. Rxd4 Rxd4 7. Ra1 Rxf4 {and it is just hopeless for white}) 5. Rcd3 Rg8+ 6. Kf3 Rg3+ 7. Ke2 Rg2+ 8. Kf3 Rf2+ 9. Ke3 Rh2 {and the h pawns are falling and white is still tied up in knots}


What should you do when opponent opens with excessive pawn moves?

The thing is, in this example you opponent didn't play all that badly. h6 and g5 looks too risky to me, but blunting your bishop (with d6) and gaining space on the queenside makes some sense. Right now b5 is a threat and you might want to prevent it by playing a4. This would be the positional treatment of the position.

There are two problems with pushing too many pawns in the opening:

The creation of weaknesses: In your example the diagonal h5-e8 is weakened and you should always consider possibilities of bringing a queen to h5.

Neglect of development: But to punish lack of development you have to open the position. This can be done by pawn levers or by piece sacrifices. Or possibly by a combination of both. Now, if you had a pawn on c4 you could play 8.d5 and answer 8…e5 with 9.Nxe5 de 10.Qh5+ and 11.Bxe5.
Unfortunately you don't have a pawn on c4 and you only promising pawn lever e4 would lose the Bg3. So you have to go more slowly. Possibly Nd2,f3,e4 is a plan. Maybe after a4.

So, to sum up:

If you develop your bishops early, your opponent might get some pawn play against them. (In your example, against both!)
You can stop expansion with your own pawns (a4 or h4) and thereby also protect your pieces from a pawnstorm.
If your lead in development gets big, search for a way to open the position. Make sure you have a pawn lever (i.e. put enough pawns in the center), consider piece sacrifices.


Is Beth Harmon behaviour in her game vs Georgi Girev acceptable (then and now)?

I think the idea was that Beth felt uncomfortable because for the first time she was no longer the young prodigy. Here was someone else younger than her competing at the same level. How would she respond?
This scene was, I understand, to some extent improvised. It seemed to show also Girev’s relative mental balance compared to Beth, at that point in her psychological trajectory. Her arrogance here foreshadows her later fall, after which she did some growing up.
Even today there are mean players, for example the one described in this chess.com post. This kind of thing is clearly against the Laws of Chess but there will be those who continue to behave like this if they find they can get away with it, particularly when facing young and relatively inexperienced opponents. Personally, the individual described seems to be horrid, and I would hate to be taught by them.
The role of the arbiter is essential in policing behaviour, particularly where young players are concerned.


Smartphone app with Wordfeud-like time constraints

You're looking for something called Correspondence Chess where you can make moves at your leisure in a time frame you're comfortable with. Chess.com and Chess Time both provide smartphone apps with this capability. Chess.com has many more features and Chess Time only provides correspondence.

iOS and Android for Chess.com
iOS and Android for Chess Time


Is this situation logically possible?

Certainly.

This is one of the known problems with using Swiss pairing when the number of rounds is close to the number of players. It is called "jamming". There is no simple software solution. For a serious tournament you would not use Swiss pairing when (Number of players) < (number of rounds + 2). Remember a round-robin tournament has (number of players - 1) rounds for an even number of players.

In real life what the arbiter does is check for potential jamming when close to the limit, particularly if there is a group of players who have only played each other. This is a warning sign that jamming is a possibility. In your case in round 7 the arbiter would check the pairing before publishing as follows:

Set all the results to draws and pair the next round. If this works there will be no jamming in this round and the arbiter would rollback the draws he entered to the correct round and publish the pairings. If jamming does occur then he would rollback and manually change the pairings to break up the jammed group of players and then check by setting all draws as before.


Why did Valery Salov quit competitive chess?

According to this article, it was because he was a pain in the ass and offended too many of chess' elite players. In fact, he seems unstable, not merely eccentric.

And more here. Looks like he decided he wasn't going to get along with people.


Should a chess engine be aware of opposite-side castling?

I'm pretty sure Stockfish doesn't have explicit code that handles opposite-side castling. What it does have is:

Some kind of "menace" score for enemy pawns advancing against our king. The closer they get, the more dangerous Stockfish thinks they are.
Some kind of "pawn shield" score for friendly pawns in front of our king. The fewer there are, the more dangerous Stockfish thinks the position is.

Therefore you get kind of a balancing act: if we castle on the same side, then we could advance our pawns against their king (getting the "menace bonus"), but it would reduce our pawn shield (and therefore losing the "pawn shield bonus"). The converse does not hold in opposite side castling, which therefore encourages the engine to push pawns against the enemy king.
Of course, the details are more complicated than this, but that's the gist.


This answer is intended to expand upon my comments, and give some concrete lines. Let's discuss the position as I (mistakenly) first thought it was presented:
[fen "R7/6p1/P3p1k1/7p/8/6PP/r7/4K3 w - - 0 1"]

This position is a draw, no matter who is to move. If White doesn't play a7, then Black's rook will have the option to pick off one of White's pawns on the kingside. So we may as well assume that White is to move, and plays 1.a7. After this, Black will be able to play 1...Kf7, to guard the pawn on e6. Let's examine the resulting position:
[fen "R7/P4kp1/4p3/7p/8/6PP/r7/4K3 w - - 0 1"]

Note that this position would have been losing for Black if it wasn't for the pawn on g7; if there were no pawn on g7, then White would win by replying with 2.Rh8 followed by 2...Rxa7 and 3.Rh7+, picking up Black's rook. But this plan is not possible at the current moment. So White has two different plans to try out: 1) march the king to b5 to free the rook on a8, or 2) create a passed pawn on the h-file, and try to remove the pawn on g7 by means of playing h6 at some point.
The first plan always fails, since Black will keep their rook on the a-file, and when White's king reaches the 4th rank, Black will place their rook on either a1 or a2. Then, if White plays Kb5, Black will give check with ...Rb1+, chasing the white king around until it decides to come back to the fourth rank, after which Black will once again play ...Ra1/Ra2.
The second plan also fails, since if White manages to create the passer on the h-file, and manages to play h6, then Black doesn't have to respond with ...gxh6, but can instead play ...Kg6 to contain the h-pawn. So the conclusion is that this position is indeed a draw.
Let's move on to the actual position you were asking about.
[fen "R7/6p1/P3p1k1/7p/8/5PPP/r7/4K3 w - - 0 1"]

This is also a draw, although not as trivial (I originally assumed that White was winning here, but I missed a simple idea that maintains the balance). Here White has an extra f-pawn, but this doesn't really make a big difference in the long run. Black will use the exact same strategy as before, putting the king on f7 and shuffling the rook along the a-file, but here Black has to be a bit more careful with the winning plan that White tries. As before, the plan of bringing the king to b5 for White is not going to work. Neither is an attack on the pawn on e6 very likely to succeed as long as Black's king is left on f7. So White only has two feasible winning plans:

create a passed pawn on the f-file, and run it to f6 to remove the pawn on g7, or
create a passed pawn on the h-file instead, with the same intention.

The first plan is not going to work well, since White will have to at the very least trade the g-pawn for Black's h-pawn, and then trade another pawn for Black's e6 pawn. At the end of the line, we will end up in the following scenario if White tries winning plan 1:
[fen "R7/P4kp1/5P2/8/8/8/r7/4K3 w - - 0 1"]

Note that if Black just sits on the position and refuses to take on f6, then White can't really do anything to make any sort of progress (this is what I missed initially); taking on g7 just reduces to a trivial draw, and marching the king to the queenside is a lost cause, as always.
Plan 2 is actually the more dangerous one, and here Black needs a bit of precision to stay out of danger:
[fen "R7/6p1/P3p1k1/7p/8/5PPP/r7/4K3 w - - 0 1"]

1.a7 Kf7 2.g4 hxg4 3.fxg4 Ra3 4.h4 Kg6! {This move is absolutely necessary if Black wants to draw. The point is that White was threatening the simple idea of h5-g5-g6+, after which Black is completely lost. Black needs their king on h7 to face this idea.} 5.h5+ Kh7! {Black can also place the king on g5, but then White still has some tricks to look out for. This drawing idea is by far the simplest one.} 6.g5 {with the intention of playing g6+} 6...g6! {This is the point of transferring Black's king to h7; if it were on f7 instead, then White could simply play h6-h7-h8Q, with a completely winning position.} 7.hxg6+ (7.h6= {and Black draws by shuffling the rook along the a-file, chasing White's king away whenever it tries to support the pawn on a7.}) Kg7!= {Black draws by moving the rook along the a-file, and chasing White's king away whenever it tries to support the pawn on a7.}


How can a Stonewall Attack player respond to 1. ... f5?

The game 1/2‒1/2(40) Dietze, Sebastian (2129) – Lorenz, Mark (2250) / Regionalliga NW 0506 (7.1), Bayern 2006, gave me a hint on how to proceed:

[FEN ""]

1. d4 f5
2. f4 Nf6 3. e3 b6 4. Nf3 Bb7 5. c3 e6
6. Bd3 Be7 7. O-O O-O  8. Nbd2 d5 9. b3 Ne4

After ... f5 I believe its necessary to stop that pawn with 2 f4; ... Nf6 was the best continuation according with an opening report, and following the same kind of white moves e3 / c3 / Bd3 to form a wall of pawns and positon the bishop to attack on diagonal b1–h7.

Dietze played 6 Bc4 which I saw as a move different of what you have shown us, therefore I preferred Bd3 and worked out the continuation with the help of a chess engine.

I see a balanced position, similar as the positions you have shown us and with a potential advance in the queen side.


The point is that after 1...Rxe3 Black will be winning material, as the sole defender of the white knight has been removed, and a pin tactic is coming. Specifically, after 2.Rxe3 (anything other than this recapture means Black has just won a piece for nothing) and 2...Bxd4, White has no way to stop the follow-up 3...Bxe3+ since the rook is pinned to the king, and so Black has netted an extra piece anyway.

[FEN "r1bqr1k1/1p3nbp/2pp2p1/2n2P2/p1PN1P2/2N1B1PP/PPQ3B1/R3R1K1 b - - 0 1"]

1...Rxe3 2.Rxe3 Bxd4 *


None of them discuss the ideas behind why those moves are good ideas,
  which I think is key in helping me understand

That's correct, the explanations are key. Opening books that don't give the ideas behind the moves along with typical middlegame plans are almost worthless. You might as well throw them away. If they don't give much more than just the moves and evaluations then you would be better off with one of the many databases.

  Most books talk about variations in the middle of discussing a
  mainline. This is hard for me because I follow that line, then have to
  reset my board to follow the mainline until the next variation.

That's very conscientious of you. Most of us would follow the variation in our heads partly because we can but mostly because we are lazy. Once you get good you will be able to do this too. If you become very good indeed then you will be able to play the whole game in your head.


Is it possible to reach King vs King by moving each piece at most twice?

Answer 1: Yes, this is possible.  Here is an example game in 27 moves:
[FEN ""]

1. a4 a5 2. b4 b5 3. bxa5 bxa4 4. Rxa4 Nc6 5. g4 Nxa5 6. Rxa5 Rxa5 7. h4 g5 8. hxg5 h5 9. gxh5 d5 10. c4 Nf6 11. cxd5 Nxd5 12. e4 Bb7 13. exd5 Bxd5 14. Nc3 e6 15. Nxd5 exd5 16. Bg2 c5 17. Bxd5 Rxh5 18. d4 Rxg5 19. dxc5 Bxc5 20. f4 Bxg1 21. Rxg1 f6 22. fxg5 fxg5 23. Rxg5 Qxd5 24. Ke2 Qxd1+ 25. Kxd1 Rxg5 26. Bxg5 Kd7 27. Bd8 Kxd8

You can even insert some moves that slow the game down so that every piece moves exactly twice.  Sadly, this is the opposite of your second question.
[FEN ""]

1. a3 a6 2. a4 a5 3. b4 b5 4. bxa5 bxa4 5. Rxa4 Nc6 6. g4 Nxa5 7. Rxa5 Rxa5 8. h4 g6 9. Nh3 g5 10. hxg5 h6 11. Ng1 h5 12. gxh5 d6 13. c4 d5 14. Qc2 Nf6 15. cxd5 Nxd5 16. e4 Bb7 17. exd5 Bxd5 18. Nc3 e6 19. Nxd5 exd5 20. Bg2 c6 21. Qd1 c5 22. Bxd5 Rxh5 23. d4 Rxg5 24. dxc5 Bxc5 25. f4 Bxg1 26. Rxg1 f6 27. fxg5 fxg5 28. Rxg5 Qxd5 29. Ke2 Qxd1+ 30. Kxd1 Rxg5 31. Bxg5 Kd7 32. Bd8 Kxd8


Where can I find a description of the "old" USCF rating system (that was in use through the 1990's)?

I found this page from Glickman which contains the old provisional formula. That formula is:

R[post] = (N R[pre] + mR[avg] + (W - L)400) / (N+m)
where R[pre] is the player's pre-tournament rating, N is the number of games upon which R[pre] is based, m is the number of games the player completes in the tournament, R[avg] is the average of the opponents' ratings, W is the number of wins, and L is the number of losses. If the player is unrated, set N=0 and R[pre]=0. The final result is rounded to an integer.

The August 1994 report of the USCF Ratings Committee discusses the old provisional system a little. There are some details in there, like how unrated players were initially treated as if they had a rating of 1000 when calculating the ratings of other unrated players.


What is the maximum number of en passants possible?

Every pawn has to take a pawn in an en passant capture, and each pawn taking another pawn will leave the 5th rank. Hence, the total possible number of en passant captures in a game is simply the number of pawns halved, i.e. 8. It can be achieved in the following sequence of moves:

[FEN "rnbqkbnr/pppppppp/8/8/8/8/PPPPPPPP/RNBQKBNR w KQkq - 0 1"]

1. h4 a5 2. h5 g5 3. hxg6/ep a4 4. b4 axb3/ep 5. a4 h5 6. a5 b5 7. axb6/ep h4 8. g4 hxg3/ep 9. c4 f5 10. c5 d5 11. cxd6/ep f4 12. e4 fxe3/ep 13. f4 c5 14. f5 e5 15. fxe6/ep c4 16. d4 cxd3/ep

This is the minimum number of moves required for 8 en passant captures, and this is due to:

All moves being pawn moves
Every pawn advancing 2 squares at its first move


Players who play fast in longer time control games

As I commented, there are several reasons why people play fast, among them:

One of the reasons I often see is fear of time trouble. Many amateurs are not really aware of whether the time they have left will "be enough", so start to move way too fast early on. They won't feel confident to play faster games either for that same reason.

It could be the case that your opponents are using your time to think if you take too much time, so when it's their turn they've already anticipated your move and figured out how to answer.

Other players want a challenge, so they will play a game in 5 minutes against an opponent who has 15.

The list could be infinite...


how to keep an offline database of my own games

PGN files is definitely the best way to go. PGN is an open and human readable format. Merging two PGN files is very easy; simply copy the content of one PGN file to the end of another.

How you want to organize your PGN files is up to you. You may want to store your PGN files all in one directory, or you may want to store them in separate directories (based on tournament, opening, result, side, etc.) under the same root directory.

ScidvsPc has the capability to browse through directories and select games you want to view. You can also manually browse the directories and double clicking the pgn will open the game directly in ScidvsPc (if you have set it up to work that way).

There is no file naming convention for PGN files. You don't need any special tools to create a single database from PGN files. Since you're on Ububtu, you can use the capabilities of the Linux sed tool to merge files recursively under a root directory.


Can you objectively determine who was the best chess player of all time?

I'm posting a sample answer to my question to give others an idea about what I'm thinking about.

First, you have to define what you mean by best. For example, does best mean you are the most dominant player for your era? Or does it mean that the quality of your player is superior to all other players. And if quality is what you mean, then how do you define quality?

Paul Morphy was probably the most dominant player. For example, when he was 12 years old he defeated a top ten player (Lowenthal) in a match 3-0. According to Edo and chessmetrics he was probably already one of the best players in the world at the age of 12! At the age of 21, he played against a simultaneous against 5 top ten players (Bird, Barnes, Boden, De Reviere, and Lowenthal) and scored 3-2.

However, most would argue that dominance is a poor indicator of who is best. After all, Morphy has been described as the first modern chess player. His competition was weak compared with subsequent champions.

Another definition that has been used is quality of play. However, this definition also has a lot of problems. In the 1900 hundreds , a number individuals argued that Steinitz or Lasker were the best players of all time arguing that their knowledge of opening and modern theory would make them superior to players from the past. However, Louis Paulsen made some very clever arguments against this hypothesis. He argued that Morphy (who had a photographic memory and memorized the Louisana bar code by the age of 19) if brought back to life would learn openings and modern theory within a year and be able to compete successfully against modern chess players.

The mathematician Kenneth Regan argues that modern chess players who have access to chess computers and modern training methods play more like computers than players of the past. That’s no surprise because they were trained by computers but does that mean that modern players are really better? This begs the question what would Fischer or Capablanca do if they had access to modern computers?   The problem with computer comparisons is they don’t take the historical factor into account.

You need an error weighting system that doesn’t just calculate the percentage of errors per 100 moves (which is basically what Regan and Guid and Bratko did ). Instead, you need to calculate the difference between your error rate and your opponents error rate. After all, chess is about committing fewer errors than your opponent. Putting pressure on your opponent to induce more errors is considered a good quality.
If innovation leads to dominance within a specific chess era over time and it becomes increasingly difficult to innovate over time as the strength of the competition increases you can’t measure true dominance by just looking at the match records of the top 30 players. That is, it’s a lot harder for Magnus Carlsen to dominate his opponents than it was for past champions.
Can the problem of increasing quality of play overtime be corrected by looking at back ratings? I prefer the Edo back rating system http://www.edochess.ca/ because the statistical assumptions are better. According to Chessmetrics, Zukertort, Steinitz, Tarrasch, Lasker, Pillsbury, Maroczy, Marshall, Janowsky, Chigorin, Schlechter, Blackburne, Duras, Teichmann, Neumann, Vidmar, Gunsberg, Rubinstein and Burn were better than Morphy.   That doesn’t ring true for me.
If you look at Edo or Chessmetrics back ratings it’s easy to see that the magnitude of the difference between the top players’ ratings has been decreasing over time. So I believe an Edo type statistical model that takes into consideration the difficulty to dominate over time would be a better approach than what has been tried previously.
So my dream analysis is that you use Edo ratings based on a database that only includes the top 20 or 30 players from each five year period. After you complete this analysis you reweight your results by a dominance factor. That is, more recent players get a bonus factor that is calculated by estimating the trajectory of difficulty of dominating over time (the decrease in rating disparities between top 30 players over time). Next, you would validate this analysis by comparing players percentage of chess computer calculated blunders their opponents make minus their own blunders. If this invalidates the above, then you need to reweight according to the computer error checking analysis if it shows there is a tendency for more recent top players to play more accurately even after my dominance factor is taken into consideration.
My guess based on my eyeballing this, is that Kasparov would do very well. But that’s just a guess.


"How are the scores decided in Chess?" - Correct?

In fact, we should be able to scale all all the PV scores by a constant. As long as the engine makes the same move, the magnitude of the scores shouldn't matter.

True. We can even add a constant to all scores (e.g. an equal position would have a score of +1) without any effect on the engine's decisions.

However, it's useful to keep the well-known score definitions:

  +1.0 is a pawn advantage for White

for 'backwards compatibility', just like we still have a 'meter bar' in Paris while the meter is currently defined with Krypton 86, so the 'meter bar' is technically slightly longer or shorter than a meter.


London System as White: exchange of the light-squared bishops

The best way to deal with the "copycat" is to switch to the Queen's Gambit with c4 with the idea of following up at the right time with Qb3 to take advantage of the weakness on b7.


What are the consequences of an early a6 in the Sicilian?

This is called the O'Kelly variation of the Sicilian.

If white plays normally (i.e. 3.d4 cxd4 4.Nxd4 Nf6 5.Nc3), then black can eventually kick the d4 knight with ...e5 when the knight doesn't have any great squares.  In this case, 2... a6 keeps the knight from moving to the natural b5 square (as in the Sveshnikov Sicilian).  This will allow black to quickly play ...d5 with equality.

White's best plan is to play either c3 or c4 trying to prove that black's move 2... a6 is not a good developing move.  When white plays c3, the natural plan is to follow up with d4, and then if black plays ...cxd4, white will respond with cxd4, gaining a classical pawn center.  When white plays c4 instead, white's plan is to set up a Maroczy bind.

An unambitious plan for white would be to play into a closed Sicilian - in the closed Sicilian, black frequently plays a6-b5 in order to get counterplay on the queenside.  Furthermore, in the closed Sicilian, tempi matter a lot less because the position will not change radically from one move to the next.


Online Sites For Earning Money Through Chess

I highly doubt that there exist one. If it would exist, it would be full of sandbaggers or engine players. There is no way to verify who exactly plays the game. You, or your Stockfish/Houdini/Rybka/.

So even if you are GM, you most probably will lose money.


What is the best continuation in this problem-h4 or Qd8?

4...Qd2+ in your main line is an error; instead Black should play 4...f4, after which he delivers perpetual check. White can try to play on with 5.Qg5+ Kf8 6.Qxf4 Qxf4 7.c8Q+ but that's still a draw. So 1.Qd8 does not work.

1.h4 enables White to escape from perpetual check, and wins.


Nimzowitsch Defence - 1. e4 Nc6 2. Nf3 variation

White loses if plays Na3, because Black is threatening with mate via Qe4. Black gains access to e4 with Bf5 move.

r1b1kb2/ppp4Q/8/3pp2n/3n3q/8/PPPP1PPP/RNB1KB1R w KQq - 1 10

1. Na3 Bf5 $19 {Black is threatening with Qe4, which leads to mate or tons of material gain} 2. Bb5+ {To clear escaping square f1 for King, with tempo} (2. Qxc7?? Qe4+ 3. Kd1 Bg4 4. f3 Bxf3 5. gxf3 Qxf3 6. Ke1 Qe4 7. Kd1 Be7 {White is defenseless, Bh4 coming}) c6 3. Qxb7 Qe4+ 4. Kf1 cxb5
5. Qxa8+ Kf7 6. Qxa7+ Be7 {White has no defense}


Its likely a transposition to the Pribyl defense.  1. e4 d6 2. d4 nf6 3. nc3 c6 where black plays e5 at some point.

Its covered in a few books about 1 .. d6 lines where black does not play g6. Also it can transpose to the Old-Indian defense when white plays c4.


Is it better to take the knight in this position?

In the initial diagram position, Black is already so much material ahead that either 1...Bxa1 or 1...Bxe5 keeps an overwhelming advantage. But 1...Bxa1 is the most straightforward, and in any case White need not allow 2...Bd3+ after 1...Bxe5 2.Nxe5. Black can first kick the knight with 1...b5 before following with 2...Bxe5 to get the ...Bd3+ idea in; that also keeps a huge plus for Black, but still the simple 1...Bxa1 is cleanest.

[Event "?"]
[Site "?"]
[Date "????.??.??"]
[Round "?"]
[White "?"]
[Black "?"]
[Result "*"]
[FEN "3r1rk1/pp2npp1/4pn2/4Nb1p/2Nb1P2/1P4PP/P3K1B1/R4R2 b - - 0 1"]

1...Bxa1
    ( 1...Bxe5 $6 {Black starts out ahead so much material that this is
    perfectly fine, but it is not best, and sloppy if nothing else.} 2.
    Nxe5 {Covering d3, so Black cannot pick up the additional exchange via
    ...Bd3+.}
        ( 2.fxe5 Bd3+ 3.Ke1 Nd7 {Black is winning handily, but won't be up
        a whole rook and pawn immediately as in the main line.} 4.Bxb7
        Bxc4 5.bxc4 Nxe5 )
    )
    ( 1...b5 {An attempt to improve on the 1...Bxe5 line, but to no avail,
    and still not as good as just snapping off the rook immediately.} 2.
    Ne3 Bxe5 {Black's first move has deprived White of the knight
    recapture, but we end up in much the same position as after 1...Bxe5
    2.fxe5 Bd3+ 3.Ke1 anyway.} 3.fxe5 Bd3+ 4.Ke1 Nd7 5.Rf2 Nxe5 )
2.Rxa1
    {Black is simply up a rook and pawn with an easily winning position.}
*


I'm not an expert on quantum computation but my understanding is that quantum computers are not expected to be useful for chess.

Quantum algorithms are very good at finding needles in haystacks: the three big quantum algorithms are Shor's factorization algorithm, Grover's database lookup algorithm and the Deutsch–Jozsa algorithm, which essentially determines whether a long list of numbers is either all zeroes, all ones or half of each.
All of these problems can be seen as examples of "I've hidden something: you must find it quickly." In factorization, I've "hidden" the prime factors and you must find them; in database lookup, I've hidden an entry with a given key in a large unsorted table and you must find it; in the problem solved by Deutsch–Jozsa, I might have placed a large number of zeroes in a table of ones but, with a classical algorithm, when you've looked at half the table and seen only ones, you might have just been unlucky and looked at the "wrong" half.  Note also that all of these problems could be solved quickly by an unrealistically parallel classical computer: you could try all the factors in parallel, look at all the database entries in parallel and look at all the values in the zero-one table in parallel.

Solving chess isn't even slightly like any of these problems. It's a fundamentally sequential activity. Whether or not my move is any good depends on what you do in response. Whether or not your response is any good depends on what I do in response to that. And so on.  You might imagine you can do the first ply of the search by taking a superposition of the possible moves.  But then what do you do at the second ply? You can't just take the superposition of all the positions we could be in after two ply because that has forgotten the tree structure. For example, consider this very artificial position, with white to move:

[FEN "1k6/ppp5/5Q2/7q/8/8/PPP5/1K6 w - - 0 2"]

If we forget the tree structure, Black is very happy. He says, "In two ply, the best position I can be in is that I deliver checkmate!"  This is true but, of course, White will never allow that, since White's best move is one that prevents Black from checkmating (or doing anything else).  Chess isn't about figuring out the best move you can possibly make in N ply: it's about figuring out the best move that your opponent will allow you to play in N ply. Quantum computers don't seem to be good at this back-and-forth, give-and-take reasoning. We don't even know how to solve chess with an unrealistically parallel classical computer.


From personal experience doing puzzles has no effect on my level of laziness. What it does, which is more important for me, is widen my thinking. I become less narrow in the possibilities I will consider simply because I have seen unlikely moves work in the puzzles I've tried.

Overcoming laziness is more a problem of motivation, will and energy.

Tony Miles used to tell the story of when his doctor prescribed beta blockers for him for a medical problem. In his next tournament he lost the first three games. Although this was bad enough it was not what really worried Miles when he tried to work out what was going on. The problem for him was that he was losing and he just didn't care. He blamed the beta blockers for this and stopped taking them with the result that he started caring more during the game about his position and so started winning again.


The two books by John Watson about strategy. These themes are considered from a historical viewpoint usually in contrast to the way they are presented in textbooks. Even if you find a favorite textbook then later you should verify everything against John Watson's books because he always gives counterarguments and counterexamples to what is established as the usual course material.


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


How does one know if a position is not reachable from a series of legal moves from the starting position?

Here is a retro which needs deep analysis:

[Title "Thierry le Gleuher; Economy Records in Add Unit(s) Problems, 5A"]
[StartFlipped "0"]
[fen "B5bn/5PrR/5prN/6pk/7p/5P2/PPPPPP2/KR1Q2N1 w KQkq - 0 1"]

The stipulation is "Add the missing unit(s)". A solution may be found in entry P1227636 in PDB. In brief:

   To disentangle Black's kingside, White must retract most pieces back home so that White can retract g2xf3. Interleaved with these White moves are 19 Black moves. But, all this time, Black has no retrotempi with units in the diagram, so they must be provided by the added units. The only way is to add black pawns on a3, b3, c3, d3, e3. Each provides 4 retrotempi, except that the b and d pawns can't both retract home, because the bishop on g8 will need to retract to c8 eventually.

Thus the position would be illegal if

   5 black pawns were added but any of them were nearer rank 7, because Black would run out of retrotempi, but it would take deep analysis to show that this is the case.

This might be the sort of situation RemcoGerlich was thinking of, seeing that

   Some White pieces need to leave the back rank and move back in a different order.

In case you thought that there's a simpler way to add units:

   A Black piece captured White's c1 bishop on c1. White is not missing anything else, so no Black pawn ever left its file. Thus White's 3 captures g2xf3 and hxgxf were of Black's 3 missing pieces: the f8 bishop, the queen and a knight. So we may add Black pawns but not a piece.


Unable To Communicate with UCI through Java Program

info depth 1 seldepth 1 multipv 1 score cp 539 nodes 83 nps 41500 tbhits 0 time 2 pv e5f6 info depth 2 seldepth 2 multipv 1 score cp 790 nodes 182 nps 91000 tbhits 0 time 2 pv e4d5 b7b6 e5f6
obviously doesn't have any best move in it. Stockfish needs time to give you a move. Your program will need to filter out those principal variation lines.
Please don't use waitTime.  Did you ask for 20 seconds? Chess engine may not stop the search exactly after 20s. Do something like this:

Wait from Stockfish in real-time. In C++, it's something like read() (can't remember exactly without a Google search). Your worker thread waits for the next Stockfish output.
Check if "bestmove" is in the line, if not, do nothing

Pseudocode looks like:
f = ... // handler to Stockfish's standard output
while (true) {
    line = f.read() // Read Stockfish's next line. Blocked if nothing.
    if ("bestmove" in line) { // Best move?
        ... parse the move ...
    } else {
        print("Do nothing!")
    }
}


How does black ensure a draw in this R+3P vs. r+2p endgame with all pawns on the same side?

The following explanation is for the general 3 vs 2 pawns on one side situation, which does apply also to this game. Of course the situation is the same whether the pawns are on the a-c files or on f-h files.

This is a fairly simple draw if you follow a few simple rules:

don't exchange rooks
do exchange pawns whenever possible
keep your king close to your pawns
if necessary block the enemy king or check using your rook

If you do this, your opponent should not be able to enter your camp or bother you with checkmate or anything.

That leaves your opponent with one winning attempt only, which is to create a passed pawn in the center (here on the f-file).

In order to prevent this, the usual recommended set-up is to push the pawn on the border of the board forward (here the h-pawn) and to protect it with the pawn on the adjacent file (here g-pawn). (This setup is already realized in the quoted game with black pawns on g7 and h6.)

This setup ensures that in order to create a passed pawn, the opponent has to exchange all other pawns first.

The resulting position with rook+pawn vs rook should then be an easy draw as the defending king is placed close to the queening square of the pawn.

The same general rules apply to 4 vs 3 pawns + rooks endgames. A good pawn structure for the defending side would be h5-g6-f7 (or similarly on the other 3 corners of the board). 4 vs 3 pawns is slightly more tricky as there are more pawns that need to be exchanged in order to secure a draw.


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

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

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


How many games to get a good idea of computer chess board rating?

There is no perfect answer here. First, and it is for a reason, FIDE says that you need 9 games to have an established rating, but the USCF says you need 25. Obviously, the more games, the closer the rating will be to accurate. That said, to really get a more accurate rating, you also need to vary the competition, and have it play against various rated humans.

I think that it is probably too weak to pair up against any modern computer program that is rated. It would get slaughtered, and not help you determine how strong it really is.

I would say at least 10.


I'm looking for a database or a collection of the chess results of all
  FIDE-rated games (standard time control).

Such a database exists but only on FIDE's computers and they don't make the data easily available in its entirety.

The data is available but you have to select and download one tournament at a time. Here's how:

Go to the FIDE Ratings Archive page. There you have the ability to Browse Rated tournaments by country. You select a federation from a drop-down list and a period from another drop-down list and click on the "go" button. For instance if you select "Russia" and "April 2019" then you get this page.

The first two tournaments are rapid tournaments but the third looks like a standard tournament. On the end of the row of that tournament there is a hyperlink "inf" for information. If you click on it then you get the general tournament information including time control and, indeed, it is

  Standard: 90 minutes with 30 second increment from move 1

Scroll down a bit further and there is a crosstable element with a blueish icon next to it. Click on it and you get the results of all the games in the tournament.

If you go back to the page with the list of tournaments for Russia for April 2019 you see similar blueish icons on the left side of the page next to the tournament names. These will take you to the same place more quickly.

If you are determined to get all the results going back to July 2001 then you can do so by building your own web crawler to navigate the site automatically and screen scrape the cross table pages for all the tournaments in all the periods for all of the federations, extract the data you want and build your own database.


Has there been much research on rating inflation?

I am surprised that the paper "Intrinsic Chess Ratings" by Ken Regan and Guy Haworth hasn't been posted yet. It is exactly what's asked for, serious research into rating inflation. PDF

Basically they got games from three periods (1976-1979, 1991-1994, 2006-2009), in several rating ranges (e.g. both players within 10 points of 2200, within 10 points of 2300, etc), and excluded types of games that might be anomalous, like team matches. Read the paper, it looks quite thorough.

Then they compared the games systematically with Rybka 3.

Some sentences from the conclusion:

  We conclude that there is a smooth relationship between the actual
  players’ Elo ratings and the intrinsic quality of the move choices as
  measured by the chess program and the agent fitting. Moreover, the
  final sfit values obtained are nearly the same for the corresponding
  entries of all three time periods.

In my view, it's quite solid evidence against the existence of rating inflation.


Is there an easy way to detect a draw in a King + Pawn vs King endgame?

There is a very easy way to detect whether King and Pawn endgames are drawn or not.

This method I use is a very easy to understand one from Karsten Mueller and Frank Lamprecht's excellent book Secrets of Pawn Endings

It concerns key squares and opposition

The rule states that if pawn has not reached or crossed the central line (5th rank for White and 4th rank for Black) then there are 3 key squares 2 squares in front of it.

For example this starting position, the key squares are b5, c5 and d5. If white's king can occupy any of these key squares then the game will be a win for white no matter what.

  [Event "?"]
[Site "?"]
[Date "????.??.??"]
[Round "?"]
[White "White to Move"]
[Black ""]
[Result "1/2-1/2"]
[SetUp "1"]
[FEN "4k3/8/8/8/8/2P5/8/6K1 w - - 0 1"]
[PlyCount "27"]

1. Kf2 {The Key squares in this position are b5, c5 and d5. If white's king
can occupy any of these key squares then the game will be a win for white no
matter what.} Kd7 2. Ke3 Kc6 3. Kd3 (3. Kd4 Kd6 $11 {Opposition}) 3... Kd5 {
Unfortunately black has occupied the key squares mentioned, there is no way
for white's king to enter the key squares, therefore, the game is a draw.
Analysis will be continued to prove this} 4. c4+ Kc5 5. Kc3 Kc6 6. Kd4 Kd6 7.
c5+ Kc6 8. Kc4 Kc7 9. Kd5 Kd7 10. c6+ Kc7 11. Kc5 Kc8 12. Kb6 Kb8 13. c7+ Kc8
14. Kc6 $11 (14. Kb5 Kxc7) 1/2-1/2

It turns out white could not occupy the key squares in time, therefore the game is a draw.

The second rule is that if a pawn is on the 5th rank (or 4th for black) or beyond, there are 3 key squares in front of it.

In this position the key squares for white's king are f6, g6 and h6

White is able to occupy one of these squares with his king and the win is secured. The variation shown shows if white had chosen a different route, black would then be able to secure the opposition and the key squares and the game would be a draw.

[Event "?"]
[Site "?"]
[Date "????.??.??"]
[Round ""]
[White "White to Move"]
[Black ""]
[Result "1-0"]
[SetUp "1"]
[FEN "4k3/8/8/6P1/6K1/8/8/8 w - - 0 1"]
[PlyCount "9"]

1. Kh5 (1. Kf5 Kf7 2. g6+ Kg7 3. Kg5 Kg8 4. Kf6 Kf8 5. g7+ Kg8 $11) 1... Kf7 2.
Kh6 Kf8 3. g6 Kg8 4. g7 Kf7 5. Kh7 1-0

One last key squares example, with a position you gave.

This is a win because White can occupy the key squares of the pawn b5, c5 and d5 (3 squares since the pawn is on the 3rd rank) without any problems

However the variations I gave are to show if white had chosen the wrong route to get to the squares, 1.Kd3 would be a heartbreaking failure as black can secure distant opposition with 1...Kd7 and can therefore control the key squares.

The second variation 2.Kc4 would also be met by brutal opposition 2...Kc6 and control of the key squares for Black.

The text moves show white occupying the key squares, sidestepping any tricks black has (and there are plenty as shown) and securing the win.

[Event "?"]
[Site "?"]
[Date "????.??.??"]
[Round "?"]
[White "White to Move"]
[Black ""]
[Result ""]
[SetUp "1"]
[FEN "8/4k3/8/8/8/2P5/2K5/8 w - - 0 1"]
[PlyCount "5"]

1. Kb3 (1. Kd3 Kd7 2. Kc4 Kc6) 1... Kd7 2. Kb4 (2. Kc4 Kc6) 2... Kd6 3. Kb5 1-0

One final position, I hope you know this one!

OK, Black has the opposition, isn't he safely drawing the game then? Well, there are exceptions to every rule, and this happens to be one. Opposition in King and Pawn endgames always works, except when the pawn is on the 5th rank and your king is also in front of it. This is an important pattern to know!

This position is a good one to emphasize the fact that King and Pawn endgames are very concrete and are based on calculation, judgement can be used with opposition and key squares but in the end stone cold analysis is the ultimate weapon; although it is best equipped with the knowledge of opposition and key squares! :)

[Event "?"]
[Site "?"]
[Date ""]
[Round "?"]
[White "White to Move"]
[Black ""]
[Result "1-0"]
[SetUp "1"]
[FEN "6k1/8/6K1/6P1/8/8/8/8 w - - 0 1"]
[PlyCount "7"]

1. Kf6 Kf8 2. g6 Kg8 3. g7 Kh7 4. Kf7 1-0


How can we make chess community welcoming to women/girls?

Addendum to address the misunderstandings that have become apparent in the comments:

What is being discussed here, is not to encourage women to play chess against their will or to fulfill some other agenda. It's about the fact that there exists an active discouraging attitude towards women in the chess world. Namely, the disrespectful attitude that players have become accustomed to, the dismissal of female players in media coverage and in the literature, the cultural bias against women playing chess (even in the west mind you) where either from childhood girls are told chess is not for them, and similarly in society.

Examples will help: (I'll avoid giving names and titles, the intent here is not to disparage people/clubs/books etc, but to give the reader an idea of the explicit discouragement that exists)

Go to any local club, almost irrespective of where you live, what you will typically witness is:

Players acting in dismay when resigning against a female player, commonly not agreeing to stay for post-mortem analysis (neither of which they have a problem with against male players), their fellow colleagues laughing at their friend for losing to a woman. This attitude is witnessed and passed on to the younger generation: boys constantly mock one another saying "haha you lost to a girl", which means this idea has already been seeded in their heads that boys are supposed to be smarter than girls. Coaches and trainers making comments to (boys) team about them being able to beat anyone in the women's team. Team coaches favoring to select men players to complete their team despite there being stronger female players in the club. Your typical first encounter with your teammates is "oh so you're the exception to the rule, it's nice to see women play chess..."

In the media coverage and literature, often there's a clear disregard towards women, e.g. books starting off in their preface by saying "they will refer to a hypothetical chess player as a he for as long as there hasn't been a female world champion!" In other words, they're saying "I'll start respecting women in chess when they become one day world champion." Or worse, books trying to give analogies for a chess concept and including sexist remarks such as: "For the lady chess player, I would use the comparison with buying clothes corresponding to latest fashion...". And sadly, the list goes on and on... A lot of these things are not just inherent to the chess world.

So as things stand, the scene is not at an equal footing for men and women, instead, female chess players are being constantly disheartened from playing the game they love, or being discouraged from pursuing it. So the discussions here are not about preferential treatment, it's about fighting against the clear bias that exists and how to give boys and girls equal chance and same level of enthusiasm to find out about this beautiful game.

Luckily, not all is lost, nowadays there are many players both men and women who are actively fighting and making a difference in this matter.

End of addendum.

Your first suggestion of separated events already sets the wrong agenda, and here I'll try to focus mostly on this aspect. Not only does the separation create the false assumption in young players' minds that the two genders cannot play at the same level, but it also lowers the number of competitions and the diversity in opponents.This would be a major setback, considering that as is there are currently far less girls getting into chess due to wrongly seeded cultural biases. I strongly recommend reading Judit Polgar's article on the importance of mixed competitions. However, as pointed out in the comments by user Greg Martin (see addendum 3), one shouldn't be completely dismissive towards female-only events either, as they do provide an inclusive safe-space to start competing in.

So first suggestions I'd have are:

Level the playing field: Organize mixed events! There should be no separation between men and women in chess, which is a purely intellectual endeavor, just like fields of mathematics or biology are.
Create a healthy environment: Prevent wrong biases from being perpetuated, as a coach or parent. Don't call a girl being good at chess as being the exception. Be encouraging towards children, and have same level of considerations towards boy and girls playing the game. If you teach or analyse games for a group of people, don't be dismissive towards the games played by your female students, and provide studies and coverage of high level chess from a diversified set of players, irrespective of their gender. This increase the chances of each of your students in finding both a playing style closer to their own and also a character that resonates with them.
To be encouraging and to popularize the game, it is absolutely mandatory to stand up against assumptions against gender bias which can makes themselves apparent in how we talk about chess players (e.g. not assuming a hypothetical chess player is male, see these discussions (1), (2) on the matter), how we write about the game (many famous chess books start outright making sexist remarks in their preface towards a potential female reader), and in our ways and manners when playing the game (related, here).

Instead of being encouraging towards women, often even the high ranking renown players feel entitled to make the utmost ungrounded misogynistic comments about women in the game. I quote below from an article on the Guardian, titled "The World Chess Championship is thrilling. But where are the women?":

  More concerning is the realisation that these unproven arguments are
  not confined to the niche world of online chess communities.
  High-ranking male chess players have a long history of making
  disparaging and misogynistic remarks about women and chess. Bobby
  Fischer, in what would turn out be one of his tamer offensive
  opinions, suggested in a 1963 interview that women were terrible chess
  players because “they’re not so smart”. Half a century later the men
  are still at it, with British grandmaster Nigel Short arguing in 2015
  that women are simply not “hardwired” to play chess.

As J. Polgar argues, a healthier competitive scene is beneficial to raising the level of play, for all players! This is important both for 1. achieving a level of normalcy in people being or becoming passionate about the game of chess irrespective of their gender, similar to how education (in any field) should be pursuable on an equal footing without bias or restraint, and 2. it helps create role models and idols for girls finding out about the game. On the topic of absence of female world champions and idols, I further quote from the previous article:

  The real reason behind the absence of a female world champion,
  however, has less to do with crude biological reductionism than simple
  statistical science. A recent study has argued that the dearth of
  women in top chess tournaments is to be expected, given the gender
  disparity in participation at all levels of the game.

  The authors analysed the population of about 120,000 players active in
  a single country, with a ratio of male to female participants of 16:1.
  Their findings highlighted that 96% of the difference in ability
  between genders could be explained by the fact that extreme values
  from a large sample are likely to be far larger than those from a
  small one. In other words, there have been more men represented at the
  world championship because more men play chess. This, in turn, means
  that a higher number are bound to reach the skill level of Carlsen and
  Caruana.

  If – then – we want to see a woman win the World Chess Championship,
  we first must address the lack of female participation in the game.
  The reasons behind this are complex, and likely manifold, but let us
  focus here on just one: the lack of prominent female chess players.

  There are no real female role models for young girls, even though
  women have been playing chess for a really long time (the first
  official Women’s World Chess Championship, for instance, was held in
  1927). There are, of course, female players who have been recognised
  for their outstanding skill, such as the Polgar sisters and the
  current women’s number one, Hou Yifan. Yet these women aren’t assigned
  the same level of importance within chess’s historical narrative as
  men such as José Capablanca, Garry Kasparov, Fischer and Carlsen. As
  all the “heroes” of chess are men, women are taught from an early age
  to associate good chess with being male.

  If we have any hope of addressing this, we need to raise the public
  profile of female chess players. Alongside the news features on
  Carlsen, we need to run one on Hou. We need to cover the Women’s World
  Chess Championship with the same fervour as the “main” world
  championship – or at the very least we need to, you know, actually
  cover it.

  Some women have already made attempts to address the discrepancy in
  media coverage and to raise the profile of female chess players. Take,
  for instance, the Chilean chess player and musician Juga, who is
  currently releasing music exploring her identity and experiences as a
  woman in chess. By branching out, she is able to both boost her
  reputation within the traditional community as well as drawing
  attention to female players among audiences who have had less exposure
  to the world of chess tournaments. It seems that this may be just the
  time to bring about the endgame of male-dominated chess.

Addendum 2: Parallel with esports

As mentioned earlier, these issues are not inherent to the chess world. On a much larger scale, same issues of toxic behaviour towards female gamers and sexism permeate the online gaming world and its underlying industry.

To read more on the topic, below are a select of articles I recommend reading:

Not one of the Fortnite World Cup's 100 finalists was a woman. Why? - From The Guardian
I Am Not a Unicorn. I Am a Gamer. By AnneMunition
'This industry has a problem with abuse': dealing with gaming's #MeToo moment

Addendum 3: important role of separated events

User Greg Martin makes an important point regarding the adverse effects of taking abrupt measures in abolishing female-only events. I quote the comment here (as comments might not be lasting in SE)

  One point of disagreement (in a sea of things on which we definitely
  agree): Polgar certainly is promoting participation in mixed
  tournaments, but that is not the same as being against participation
  in female-only tournaments, and I would suggest not dismissing them so
  quickly. One of the characteristics of systemic sexism is that it
  creates situations for which there is no great solution. Having
  female-only events is not great, but not having them is also not great
  (you have described many of the reasons why). Feeling included is a
  very powerful aspect of the situation.


Why is 16. d5 a blunder in this position?

The move 16. d5 is not necessarily a blunder. Although it is not good for White, it is not losing. Lichess and other chess engines sometimes see positions differently from how humans would percieve them.

That being said, analysis on chess.com deems it a a mistake. which is much more reasonable. The reason is that, in the long-term, the d5 pawn mught be lost, giving Black a +1 advantage, in material worth, at the least in some lines.  Even if White retains a pawn, the doubled pawns on the queenside will be a disadvantage that Black can use, or there will be some other disadvantage Black can create for White.

All in all, White will have some sort of positional weakness no matter the outcome.

Here is a computer generated line that shows how Black gets the upper hand in the long-term with an extra pawn. I do not claim that this is the 100% best play, just that it shows one of the many general outcomes where Black has an advantage.

[FEN "rn4k1/pbp1qr2/1p1pp2p/5pp1/2PP4/2PBP1B1/P1Q2PPP/R4RK1 w - - 0 1"]

1. d5 Nd7 2. Rae1 Raf8 3. f4 Nc5 4. e4 fxe4 5. Bxe4 gxf4 6. dxe6 Bxe4 7. Rxe4  Nxe4 8. exf7+ Rxf7 9. Rxf4 Rxf4 10. Bxf4

Note that although f4 is technically an inaccuracy, it is perhaps best by human play.

Here is another line that shows how Black can get an advantage in other ways as a result of White’s mistake.

[FEN "rn4k1/pbp1qr2/1p1pp2p/5pp1/2PP4/2PBP1B1/P1Q2PPP/R4RK1 w - - 0 1"]

1. d5 Nd7 2. Rae1 Raf8 3. f3 Ba6 4. Be2 e5 5. e4 f4 6. Bf2


Assuming this is a chess problem, then you want to start by looking at things that show up as problem themes, more than as game themes.  There are a few salient features of the position:

White's queen-bishop battery; it seems very likely that discovered checks from the bishop are likely to be a mating resource.
The white bishop being on a line with the king, thus leaving it vulnerable to a pin from either the Ba7 or the Qa6.
The open h-file, and in particular the possibility of a king-rook battery to deliver mate.
More remotely, the possibilities for interference between the black pieces (e.g., bishop/rook interference on c5).

Given these, I would investigate the possibility of a move like Rh1; this offers up the threat of 2. Be3+ Kh5  3. Kg1 mate and forces black to defend immediately. The most natural defenses are via the aforementioned pinning moves, 1...Bb8 and 1...Qd6, so I'd start looking there.

--

Assuming, OTOH, that the problem is a tactics puzzle more than a 'chess problem' problem, then I'll just point out that your analysis missed one particular bishop check, and you should consider the question of where the bishop can go that covers key squares in the vicinity of the king; not just for a mating net, but also as possible 'drop points' for the queen.


Chess variants-Anyone recall the name for one that has a "superpiece" with the movements of the queen and knight?

According to the Wikipedia variants page, there does not seem to be a variant with a specific name, but there are several variants that use the queen-knight hybrid, which is called an Amazon (appropriate name, and combines rook+bishop+knight movement abilities). So maybe just "Amazon chess" would make sense.

The Amazon is used in the following variants (copied from the Wikipedia page above):

Maharajah and the Sepoys: Black has a complete army, and White only one piece: the maharajah (Amazon).
Musketeer Chess: A commercial variant, inspired from Seirawan Chess. This variant introduces 10 fairy pieces: archbishop, chancellor, hawk (different rules from Seirawan Chess), elephant (different rules from Seirawan Chess), leopard, cannon (different from Xiangqi), unicorn, fortress, spider, and amazon (also called dragon in this game). Players have a choice of 2 pieces among the 10 possible and method used to introduce them during the game.
Wolf Chess: On an 8×10 board, with fairy pieces wolf (empress), fox (princess), nightrider, sergeant (almost a Berolina pawn), and elephant (amazon). By Arno von Wilpert (1943).

There are also the following hybrid pieces:

Empress (rook+knight)
Princess (knight+bishop)
The traditional Queen (rook+bishop)


The position very much looks to be a draw. The white king can't advance easily as the black rook stays on the third rank. All the maneuvers to bring back the white rook to help advance don't seem to work as both f4 and d4 can be weak. Furthermore the black king can stay on the d file to cover the e7 and c7 square while always having Kd7 if White attacks the weak e6 or c6 pawn from the side.
Therefore the only way to make progress for White is to play 0...Kd8 1.f5 exf5 2.Rxf5
Now White faces a similar problem. The d4 pawn is weak so as soon as White blocks with the rook on the third rank the black rook will move to the fourth rank and keep the d4 pawn attacked. For instance 2...Rh3 3.Rf3 Rh4 . To make progress White would have to block the fourth rank. However if White plays Ke3 Black can respond with Re4+ forcing the king to d3 from which it can not support a move like Rf4 blocking the fourth rank.
This of course is not a proof but I am very sure that for the reasons outlined here, the position is a draw under all circumstances.


Best performing algorithms are YBWC and DTS. Lazy SMP is probably giving best performance/complexity ratio. You can read more about parallel search algorithms here (make sure to check referencies and links.
As for reference realization, I haven't seen any, so I just used simpler engines with parallel search,  and, mostly, algorithms descriptions.


How to deal with the Sicilian Wing Gambit?

The easy way out is to just play 2…b6. This move certainly doesn't "just worsen" blacks position:

Now both players can fiancetto the bishop, but a black bishop on b7 actually has a target, the e4-pawn.
If white plays 3.bc bc the b-line is open. This makes the option of 0-0-0 quite unattractive, an option that is much more often utilised by white, especially in the sicilian.
If white doesn't take on c5, he will sooner or later have to deal with the threat against b4. Actually, he will have to evaluate the threat against b4 every move!


White fights for equality in French classical?

An evaluation of +0.2 is just noise and nothing like a "slight edge". Another engine might very well give you -0.2 or so. I would not be overly concerned by such evaluation.

When analyzing opening lines, much more important is the character of the position: whether you like it, whether it  gives you winning or drawing chances (depending on requirement), whether it is easy to play for you (and difficult for your opponent), etc. All of these are difficult to assess automatically with a computer and require you to look at it. That's why GM spend so much time on openings and don't just have their computers running looking for the line with the highest evaluation.


What is a good French-like defense against 1. d4?

One option is to play 1... e6 against 1. d4 anyways!

After 1. d4 e6, white doesn't really have a choice other than to transpose into a standard opening anyways.  If white plays 2. e4, well that's just the French Defense that you know and love.

If white plays something else, like 2. c4 (as most Queen's Gambit players will), then you have a few options:

Queen's Gambit Declined (2... d5)
You have to be prepared here because white will most likely know a few good openings.  There are some obvious similarities between the French and the QGD (black's light square bishop!), but there are a few key differences that you will need to practice.
Benoni (2... c5)
If you don't want to deal with a symmetrical game, the Benoni is a good option.  However, this is likely to lead to a fairly tactical game after 3. d5 exd5 4. cxd5 d6.  Since you weren't thrilled about a tactical melee, that brings us to the...
Dutch Defense (2... f5)
Although the Dutch Defense doesn't have the best reputation, it fits your criteria: it's not very tactical (at least the Stonewall, the Leningrad is a totally different story!), black will have some positional trumps (namely the e4 square), and it's offbeat enough.  Black's simple plan is to setup pawns on f5, e6, d5, and c6 and then stick a knight on e4.  The whole battle revolves around control of the e4 square, and black has had good results with the Stonewall Dutch.

After mentioning all that, 1. d4 e6 2.c4 can also lead directly into Indian structures with either 2... Nf6 or 2... b6 (the Nimzo and Queen's Indian respectively).  If you are familiar with one of these openings, this is a good way to try to get a French, but fall back on a main line opening if your opponent doesn't oblige with 2. e4.


King's Indian Attack - Middle game ideas

The best way to learn the KIA is to study master games. White attacks on the kingside, and black attack on he queenside. Study Fischer's KIA games as well as the KIA games of others.


Carlsen beat a high ranking GM with 1 Nh3. Conclusions?

It was one game in online rapid. You cannot deduce from one game that 1.Nh3 is sound or not sound. Carlsen was actually MUCH worse out of the opening, and just outplayed Dreev later. It really means nothing other than Carlsen is currently much stronger.

Most likely 1.Nh3 is not good, and this is unusual for a first move: Stockfish already evals this as -.62 at a depth of 50.


The Cochrane Gambit sacrifies his Knight for a few things:

He sacrifies the Knight for 2 pawns
After Kxf7, Black loses castling rights and is dangerously in the
center.
Blacks King-side is basically destroyed with only the g and h pawns
and it is not easy to find the best square for the Black King.
Usually White will check with the Bishop with Bf4 and if Black
blocks with Be3, then White should just exchange bishops and bring
the black king further into the center making it harder to castle
manually.
White wants to build a strong pawn center by pushing his pawns
especially on the king-side. For example, White wants to develop his strong pawn center by pushing d4, f4, e5 and further fortify his strength in the center with Nc3 and Bd3 or Bf4.

With the above said, I think Black's goal should be to neutralize White's strong pawn center. In the Kramnik-Topalov game, I think Kramnik made a good move with 5...c5 to challenge the d4 square. From here White has to chose between playing 6. f4 followed by 7. e5 trying to break Blacks position, but in this case White's Bishop on c1 is not playing. Topalov instead played 6. Bf4+ to not lose any tempo and 6...Be6 is basically forced and after the exchange of Bishops, Black's King is more brought deeper into the center.

Some popular replies for Black after 5. Nxf7 Kxf7 6. d4 could be:

c5
g6
c6
Qe8
Be7

Lets look at the c5 first:

[FEN ""]
1. e4 e5 2. Nf3 Nf6 3. Nxe5 d6 4. Nxf7 Kxf7 5. d4 c5

White's most popular reply is 6. dxc5, followed by 6...Qa5+ 7. Nc3 Qxc5 8. Be3 and White maintains his the initiative.

Now onto c6:

[FEN ""]
1. e4 e5 2. Nf3 Nf6 3. Nxe5 d6 4. Nxf7 Kxf7 5. d4 Be7 6. Nc3 c6

Usually with 5...Be7, Black wants to try to castle manually and White continues development with 6. Nc3. After 6...Re8, Black is in trouble after Bf4+, so instead 6...c6 with the plan of playing d5 later. After 7...d5, it might continue 8. exd5 cxd5 9. Nxd5 Nxd5 10. Qh5+ Kf8 11. Bxd5 Qe8. I would say White is better here because his Black's King is still weak and he has 3 pawns for the Knight

Regarding g6:

[FEN ""]
1. e4 e5 2. Nf3 Nf6 3. Nxe5 d6 4. Nxf7 Kxf7 5. d4 g6

g6 might be Black's most popular reply. After 6. Nc3 Kg7 7. Be2 d5 8. e5 Ne4 9. Nxe4 dxe4 10. O-O Nc6 11. Be3 h5 12. f3 exf3 13. Rxf3 Be6 14. c4. Even with this, White still has an advantage.

Last, Qe8:

[FEN ""]
1. e4 e5 2. Nf3 Nf6 3. Nxe5 d6 4. Nxf7 Kxf7 5. d4 Qe8

Here Black threatens e4. It usually continues: 6. Nc3 g6 7. Bd3 Kg7 8. O-O Nc6 9. Bd3 Nc6 10. Be3 Nb4. White may panic here because of the attack on the White-Squared Bishop, but instead of panicking, White should play 11. h3 Nxd3 12. Qxd3 Rg8. Black wants to play Kh8, so White should go for the attack with e5. Black is very disorganized and in a positional disadvantage.

In a nutshell, I believe breaking White's center as Kramnik did is the best possible way to either draw or defeat the Cochrane Gambit


Is there a website that supports blind chess?

Lichess has an option to play blindfolded if you have an account registered.
You have to activate the Speech Sound effect, in the upper right corner → Sound → Speech.
To enable writing coordinates(e.g. Nxe4) instead of moving pieces you can activate blindfold mode in your game display preferences.
Enjoy your games!
Source


Well, both sides are trying to develop their pieces.

For White, Bc4 develops his bishop and points at the important f7 square. Nf3 develops his knight and controls d4 and e5. He could also eventually now play Ng5 aiming again at f7.

Black also wants to develop his pieces. ...Nf6 is often one of the first developing moves Black makes, clearing out pieces from his kingside back rank so that he can castle, but right now 4...Nf6 would be silly because White would just play 5.e5 and Black's knight would have nowhere to go except back to g8. So other ideas of his include

4...d6, controlling e5 to make ...Nf6 possible, and also clearing space for his light-squared bishop to develop
4...Bc5, developing his bishop and taking one step towards castling kingside
4...Nc6, developing his knight and controlling the central squares d4 and e5
4...Bb4, with some of the same ideas as ...Bc5, also creating a pin so that White's knight can't move and e4 is less defended.

No crazy tactics, just getting your pieces all out there so you can start fighting.


I'm struggling to find the full solution of a chess problem

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

1. Ba6 h2 2. Bf8!

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

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


One of the early pioneers, if not the actual founder of the Hypermodern style was Richard Reti, early in the 20th century. An example of this kind of play is his own Reti Opening.

The theory behind this is that center pawns on the fourth rank (or further) can become weak as well as strong. So the idea is to move out knights first, then pawns to the third rank, followed by bishops, etc. Then wait till the opponent commits his pawns to (his) fourth rank (your fifth) before deciding when to move yours to your fourth rank.

An "extreme" example is Alekhine's defense, when Black plays 1... Nf6 in response to 1. e4, to provoke further White advances, and (presuambly), weaknesses. The disadvantage to Black of moving the knight around seems to offset whatever disadvantages White may incur by advancing his pawns. Alekhine's Defense variation, understanding white's overextended pawns, black's multiple early knight moves

But if White opens 1. Nf3, he deters ...e5, and limits Black to playing ...d5 (or ...d6, if he wants to enforce ...e5). Hence, "hypermodern" openings beginning with knight moves seem to work better for White, who has the advantage of the first move. This advantage does give White a number of options, including playing "colors reversed" openings with an extra move that Black doesn't have.


Can a knight move through all squares from its original position?

Yes, it can

This particular knight's tour is closed, meaning that it starts and finishes in the same square. Therefore, the knight can start at any square on the board and finish on the same square, since it just starts at a different point along the cycle.


Is my dark squared bishop that important in this position or what's
  the idea behind this?

Yes, your dark squared bishop is very important in this position. Your opponent doesn't have one, so yours is unopposed. Furthermore you have the minor advantages of the two bishops.

Doubling your opponent's pawns isn't as big a plus as you imagine in this position. Yes, it weakens Black's kingside but it also opens the g file for his rook which could, in the short term, more than compensate.

Finally, you have some very good threats with your bishop against the awkwardly placed Black queen. They don't quite work immediately but both Bg5 and Ba3 could be very embarrassing with the right preparation. A move like Qb3 prepares both and could be a good move to start with.


Is it disrespectful to pay attention to other things while playing?

Whether or not your opponent is offended may depend on your local culture outside of chess, and might also depend on the situation in which you're playing the game. In a tournament with slower time controls, it's not uncommon to even see players get up and walk over to watch other games in progress. On the other hand, if you're just playing a casual game with someone then it's probably polite to pretend you're interested in the current position because otherwise your opponent may think that you don't actually want to be playing with them.


The old Fritz 5.32 (last free version) does this. Of course it is not as powerful as the latest version (big understatement). It is available here http://freechess.50webs.com/fritz.html but note that it will need some work (described on the website) to get it to run on modern versions of Windows.

I alternate between Fritz 8, which is not quite as old as the free version and runs on modern operating systems, and Scid vs PC which is a much more modern fork of Scid and could also be worth trying especially if you are still stuck on original Scid.


Draw rates in classical chess between elite players?

For over 2700 rated players,  statistically the draw rate is slightly under 50%.

For all over 2200 ,  the rate is just under 40%, statistically.


How do correspondence players keep track of ideas during games?

I write a short description in my notebook for each move I make, unless it is a trivial move (e.g. a forced recapture, an opening move I know already or an endgame that I know already).

I try to imitate the style used in Logical Chess by Irving Chernev.


The following can be found on USCFSales Steve's ChessBase Tips:

“Full analysis” mode is likely the better choice for less experienced
chess players, due to the relative brevity of the alternative
variations it provides, the short verbal commentary, and the fact that
variations are evaluated symbolically rather than with numerical
values.
Blundercheck gives much more "hard" information than does "full
analysis".
The core purpose in both forms of analysis remains the same: to show
where each of the players went wrong and what they should have played
instead. “Full analysis” mode provides the information in a much
simpler form.
“Blundercheck” mode will only show improvements, not “what if…?” moves
which are actually worse.

You can find much more information on the website provided
above.  The author, Steve Lopez, has been the authority on ChessBase/Fritz software for nearly two decades.


The pawn on d3 is not backwards since (as you say) it is protected by another pawn.

There must be something missing from Wikipedia's definition. Later on the article (http://en.wikipedia.org/wiki/Backward_pawn) contradicts itself.

  Also, the opponent can place a piece, usually a knight, on the hole in front of the pawn without any risk of a pawn driving it away.

In your example, if black puts a knight on d4, the pawn move c3will drive it away.


In an offhand blitz game without touch-move

In other words, you are not playing by the official rules of any chess federation, either national or international. You are playing by your own rules. So, you and your opponent, as the arbiters of the rules you are playing by, are the ones to decide whether or not what was done was legal.


Why is White's "25. Bh4" considered a great move in Karjakin vs Kramnik at FIDE Candidates Tournament 2018?

The reason behind 25. Bh4 is very concrete, namely: With Rf8 coming next for black, white's bound to play Kg2 to unpin and cover f3 but without preparing it with Bh4 it leads to the following forcing variation:

 [title "25. Kg2 without Bh4"]
 [fen "r5k1/p5p1/2p1b2p/2b4P/5q2/5B2/P7/1R1QBK1R w - - 0 1"]

 1. Kg2 Qg5+ 2. Bg3 Rd8 3. Qxd8+ Qxd8 4. Rb8 Bc8 5. Bg4 Qd5+ 6. Kh2 Bd6 7.Rxc8+ Kh7

This line forces white to give up the queen for the two pieces, and it is definitely still among the winning variations for white but for practical reasons I reckon Karjakin intended to keep his queen on the board and avoid that variation for good, which he perfectly achieves with 25. Bh4 as it stops both Qg5+ and Rd8 and sets up Kg2.


Can playing blindfold chess be learned or is it a natural skill?

In essence, you are asking-

  Can memory (or other brain functions) be improved or is it a natural trait?

The answer is yes to both. While it is true that one's memory can be improved, it is also commonly observed that some people are more "gifted" when it comes to memory (and other brain functions) than others.

To play blindfold chess, you need three things -

A decent memory
A good ability to visualize
A decent level of chess playing strength (if you want to play decent chess i.e. or one could simply have a fantastic memory and make legal yet nonsensical moves).

Memory

I never "practiced" blindfold chess to learn it. I simply observed that as soon as my chess level got to FIDE 2000 level (for example), I could easily replay moves in my head and think "blindly". I don't have a great memory. I suppose my memory is average or slightly above average, but chess has surely helped to improve it to some extent.

Visualization

The way I do it is by visualizing a 2D board in my head (like a computer screen). The board doesn't have to be crystal clear (it's often hazy), but as long as you can "see" the pieces in their places, it's fine. I suppose that a chess player's ability to visualize increases the more chess he/she plays. This is normal brain development. The more you exercise a muscle, the better it gets. So I would suggest you practice visualization to get better at it.

Playing Strength

The real point of blind chess is to play chess blindly and yet play it well. So playing strength is indispensable or else there is no point in playing blind chess. If you play blind chess badly, you only prove you have a good memory and visualization power and nothing more. So, as an amateur, I would say your top priority is to improve your playing strength. Work on that and your memory and visualization will automatically improve.

All the best!


Black usually reaches the Stonewall formation from the Dutch Defense (though QGD is an option as well, if he/she postpones Nf6) and involves putting pawns on c6, d5, e6 and f5. These pawns guarantee a strong grip on the light squares in the center (especially e4, which is often occupied by a knight later on), but weaken the dark squares. Another problem for Black is the light-squared bishop, which is severely limited by its own pawns. A typical Stonewall position is the following:

[FEN ""]

1. d4 f5 2. g3 Nf6 3. Bg2 e6 4. Nf3 Be7 5. O-O O-O 6. c4 d5 7. Nc3 c6

It's hard for White to crack Black's center, but he has many options, of which my favourite is to exchange some pieces and take advantage of Black's bad bishop in the late middlegame and endgame.

As @user1583209 notes, if White tries to reach this formation it's called the  Stonewall Attack – see the linked question for more details.


Reply for C11 French/Steinitz after `5. Nf3 c5`

The plan for white is to secure the e5 square. Black's freeing maneuver will be to play f6, and the resulting position will have a backwards pawn on e6. Therefore, white's plan will be to place his bishop on f4 and move his knight to e5, perhaps with support along the e-file from a rook or queen.

A possible variation could continue as follows:

rnbqkbnr/pppppppp/8/8/8/8/PPPPPPPP/RNBQKBNR w KQkq - 0 1

1. e4 e6 2. d4 d5 3. Nc3 Nf6 4. e5 Nfd7 5. Nf3 c5 6. dxc5 Bxc5 7. Bd3 Nc6 8. Bf4 f6 9. exf6 Nxf6 10. O-O O-O 11. Ne5 Bd7 12. Qe2

Keep in mind that this isn't the only way of playing the Steinitz. White more commonly plays 5. f4, bolstering his center pawn on e5 before continuing to develop with Nf3. Also, 6...Nc6 is considered a more accurate move for black, leaving the option of capturing on c5 for a later move and saving a tempo to attack the e5 square.


How would you analyze this critical position from my most recent game?

These positions are good for a robotic approach, which is my favourite. I would try to come with candidate moves.

First I would try to eliminate quickly (or find miracles in) Qxh6+ and Rg7+
Then I would go for two more obvious checks, Bd3+ and Qe4+. I would try to get as much feeling about what's going on in these lines, find their problems to have chance to find (if necessary) some hidden properties of position (like Bd3+ is almost mate if we prevent black piece to go on f5.
Then I would go for mate threats, trying to quickly eliminate Rg6. From point 2 I should already know that Nxf7 might be a mate threat, even if I can miss this for now and come with the move later during capture searches.
I would go for captures and light threats, trying quickly to eliminate nonsense again. Probably here would be Qxe7, Rg8 and of course Nxf7, if not in the previous point. I guess Ng4 could stay hidden from my sight forever as the move came to my mind after writing the whole post. Engines wouldn't make such a mistake :-)

Depending on what would come from this search, which I think shouldn't take more than 5 minutes, I would try to sort candidates from the one I like the most. Well, Nxf7 is a big and obvious candidate. It threatens mate and after Rxf7 it is not even a sacrifice. So I would go for it, unless I would have even better feelings about checking lines Bd3+ or Qe4+. That is possible, as I would have already solid cover of these now. Ok, calculating Nxf7 is another story, you will do similar work like here. Find opponent's candidates, being careful, as your queen is hanging and you are a piece down. When I know only Rxf7 is serious, then I would go for Bd3+ and Qe4+ as a huge candidates. If I find some problem there, I would try to come with other candidates like Qg4. You probably don't search for all weird candidates in later moves of calculation, as your head could explode by doing that. That is a reason why we sometimes miss nice combinations. Always checks, mate threats and big captures and threats first in start position and then later, the less candidates.

In my answer to this question you can see the most brutal combination I could have in my game, but wasn't found during the game either by me, or by my opponent. Was cool to hear how lucky I am, as the computer saw it immediately. You look for calm moves in the beginning, but find the 4th calm move in a row in such a firefight!


Is there a way to use handicaps in chess to bridge the gap between players of different skill levels?

Handicapping changes chess in a fundamental way that stones in go do not.

In go, getting an extra stone is roughly equivalent to having an extra move.  In chess, losing a piece is catastrophic, and in a game between two players that are within ~300 rating points, losing a piece means loss of the game.

One other reason that handicapping is not done this way is that while you (1500 player) might lose to a 2200 player (barely) without a knight, it is highly unlikely that a 2000 player would lose to a 2700 player at a tournament time control.

Handicapping was done before rating systems became so prevalent.  In clubs, players would be said to be "knight players" meaning that they needed odds of a knight in order to give a stronger opponent a good game.  Similarly there were "pawn" players and "rook" players.

An easier handicap between two roughly equal opponents would be to give the weaker player white.  This is roughly equal to 25-40 rating points [1].  Another common handicap is for the stronger player to play "blindfolded", meaning that he or she cannot look at the board, but has to call out the moves in order to play.


What was the first chess engine that could beat the world champion on a standard desktop?

Deep Blue was a super computer. In the 2006 match, Kramnik was defeated by Deep Fritz that everybody could buy.

  In a November 2006 match between Deep Fritz and world chess champion
  Vladimir Kramnik, the program ran on a computer system containing a
  dual-core Intel Xeon 5160 CPU, capable of evaluating only 8 million
  positions per second, but searching to an average depth of 17 to 18
  plies in the middlegame thanks to heuristics; it won 4–2.[31][32]

(source)


I heard professional chessplayers must train physically as well as mentally. Why is that?

You've heard it right. Physical training is as important as mental training in chess. Thinking is an energy intensive activity and often has a direct effect on the physical body.
Quoting this scientific american article by By Ferris Jabr on July 18, 2012, brain weighs about 1.4 kilograms, only 2 percent of total body weight, it demands 20 percent of our resting metabolic rate (RMR)—the total amount of energy our bodies expend in one very lazy day of no activity.

Karpov had lost 10kg (22lb) over the course of 1984-85 Kasparov-Karpov world championship match. Quoting Kasparov from this interview, I pay a lot of attention to my physical condition; to be fit under the terrible pressure of big competitions. Obviously this is becoming more important with age.

From a study by Speakman JR et. al , being physically fit improves resting metabolic rate (RMR) which is a major contributor to daily energy reserve and thus any increases in RMR in response to exercise interventions are potentially of great importance.

Chess, as you know is a brain intensive activity and thus RMR plays an important important role. Therefore from the 1st and the 3rd paragraphs, it is clear that physical fitness improves mental fitness and therefore beneficial to chess.


Could I get in trouble for insulting an arbiter during a tournament round?

Incidentally I'm a national arbiter and a passionate player at the same time. Here is the rules side: FIDE rule 11.1 forbids the player to do anything bringing chess in miscredit. We have no yellow card (actually, I do have one in my arbiter kit, just in case :-) but insulting the arbiter definitely falls under 11.1 and is punishable by all the 12.9. sanctions (and yes, 12.9.9. allows to throw a player out of a tournament, but the punishment must fit the crime).
Now the big question is: why should a player insult me? 90% of all decisions are clearly governed by FIDE laws, I simply tell the player why law isn't on his side, and chess players may be wackos, but they are reasonable wackos. ;-)
A further 9% are lie-vs-lie situations (say piece touche and I didn't see it) where I have to make a decision on good faith. I communicate that too, the players will accept that too even if I factually wronged one. OK, assume that it's one of these situations where everything went south and the player calls me a frelling drenhead in the heat of the battle. Guess what, I think "so's your mum", a good arbiter should be able to handle such a situation with dignity. And as Brian suggested, it's very improbable he pulls out the nuke.
That said, in my player career (and I'm 60 and play around 50 tournament games in a normal year), I personally observed the following...
1 act of physical violence (to my best knowledge, the perpetrator got life - chess exclusion, that is),
1 act of justitiable name calling (the two are arch enemies and probably would kill each other if unattended; the called kept an ice cool, making the caller look like a complete idiot, he probably scored this as check mate),
zero incidences of insulting me either as player or arbiter.


It is taught together with the rest of the rules of the game. You playing for years without knowing about it has nothing to do with that, either you learn the rules or you don't, you won't self-discover them no matter how many years you play, specially not when your playing pool is limited solely to your friends who may not know certain rules either. So you not knowing about it doesn't make for a case that it's poorly taught.

Now chesswise, I think it's quite clear why it's a relatively rare type of move given that it can only be played when there are still pawns at starting position and when moved two squares, constraints make events rare. That said, its potential as a move is still rather frequently employed, for instance to stop your opponent's desired queenside pawn expansion, following is a typical example:

 [Title "En passant being employed"]
 [fen "r1bq1rk1/pp1nbppp/4pn2/2pp4/P2P1B2/2P1PN2/1P2BPPP/RN1Q1RK1 b - - 0 8"]

 1...a6 2.a5 b5 (2...b6 3.axb6) 3.axb6

Black plays a6 to prepare b5 and their desired setup is to have the a6-b5 pawns which provides important light-square control and creates space on Black's queenside. White on the other hand, prevents it by simply playing a5, with the underlying tactical idea being to capture with en passant in case black tries to expand with b5. If black did play it regardless, then after white takes, black's left with a weakened a6 pawn. So with a5 we stop both b6 and b5 for good.


What squares are the most active for bishops?

The f3/f6/c3/c6 tend to be where most knights are exchanged. That is because in beginner play, if the opponent tries to push the pin with h3/h6/a3/a6, the person who has pinned the knight with the bishop typically exchanges, and this tends to be a beginner fault..


The inclusion of 2. Nc3 ahead of f2-f4 is most significant.
Consider 1. e4 e5 2. f4. Does 2. f4 aid White's development? Does 2. f4 make a threat? In both cases, no. 1. e4 e5 2. f4 isn't a threat because if we gave White an additional move for 3. fxe5, then 3...Qh4+ ruins White's day. That's the first reason for 2. Nc3: by guarding e4, it means f2-f4 will make a genuine threat of f4xe5 because following ...Qd8-h4+, ...Qh4xe4 is out of the picture.
The other reason for 2. Nc3 is its influence on d5, given that when White plays f2-f4 as a means of getting the upper hand in the center (by deflecting the e5-pawn, or capturing it), Black's simplest counter in the center is ...d7-d5. However, it does not at dissuade Black from  2. Nc3 Nf6 3. f4 d5, by far the most common continuation.
If White wants to play this flavor of Vienna, he has to like the positions that result from 4. fxe5 Nxe4 5. Nf3. If White really wants to shut off ...d7-d5, he can postpone f2-f4 for still another move with 3. Bf1-c4. That invites the craziness of 3...Nxe4, which is a whole 'nother ballgame.
2...Nf6 3. f4 d5 is most common, but say Black lets White carry out his plan. Suppose 1. e4 e5 2. Nc3 Nc6 Then 3. f4 exf4 4. Nf3. Black is willing to go for this because the knight on c3 is sort of misplaced!
Again, consider the immediate 2. f4. 1. e4 e5 2. f4 exf4 3. Nf3
(3. Bc4 was the choice of Fischer and Polgar, allowing 3...Qh4+, for whatever that' worth. Keres played 3. Nc3 in his brash youth, after which 3...Qh4+ is more meaningful because White's flight is Ke1-e2 rather than Ke1-f1. Steinitz tried the most thematic 3. d4, but 3...Qh4+ compels 4. Ke2 in that case, also. I wrote an entire book on 3. h4.)
3...g5 4. Bc4
(4. h4 is more positionally logical, though 4. Bc4 is equally popular, partly because some players with Black will choose 4...g4 5. O-O gxf3)
4...Bg7.
4...Bg7 is a huge move, mostly because it guards the h8-rook,. so 5. h4 doesn't force ...g5-g4, but can be met by 5...h6 6. hxg5 hxg5 7. Rxh8 Bxh8.
And since ...Bf8-g7 is such a useful move for Black in those King's Gambit Accepted positions, White would rather leave c3 open for the pawn to support d4 (but that Vienna knight prohibits that, and is therefore somewhat misplaced — how ironic).
About 1. e4 e5 2. Nc3 plus 3. g3. There White is keeping f2-f4 in reserve for a long time, after his kingside development is complete (the Bg2 influences Black's main counterattack square d5 from a distance), and the queenside has d2-d3, after which f2-f4 will have the Bc1 behind it and the  Pg3. These positions are actually very quiet because the pieces don't come into contact as quickly (obviously g2-g3 plus Bf1-g2 is less combative than Bf1-c4 which invites a fight with ...Ng8-f6 plus ...d7-d5). In many of those games, White kept f2-f4 in reserve until it most safe, and then goes on with f4-f5 to take all the kingside space (presumably while Pe4, Nc3, and Bg2 keep Black under wraps).


Checkmate ends the game - there is no agreement/concession involved. If it’s not checkmate the game has not ended. And a handshake is not a move which needs to be “retracted”.

If the error was only realised significantly later, then maybe it’s a different case. I can see that an arbiter might deem the handshake to be a resignation. But that’s not the case here: they just played on and did not mark the scoresheets.

Your daughter does not need to be an expert in the rules (which cannot not be exhaustive in any case) but does need the reflex to call the arbiter or tournament director in any kind of dodgy situation.


Software for reading multiple FEN positions

A file that contains one FEN per line is a file format in itself. It's the file format used by test positions for chess engines. So engines definitely have some process to analyse all the positions in a FEN file.
(Ermm... your FEN is missing the king-castling, move number and who is to move indicator -- you'll want those.)
An alternative would be to convert each FEN line into a PGN game -- The FEN line goes in the PGN header, e.g. [FEN "1b6/4pKn1/8/1nPkqp1R/2pr3p/3b1pp1/P3Qp2/2BRr3"], and the comment can just be a "Before move annotation". So you could construct a minimal PGN game for each position -- and PGN is supported by absolutely every single piece of chess software out there. There is a minimal set of headers required for a valid PGN game, White, Black, Site, and Result. Plus that FEN header.
Scout around, maybe you can find a fen2pgn script. There was one a few decades ago.


Why did Puzzle Rush stop at the second fail?

There is a 'quit' flag on the webpage of puzzle rush, so perhaps you could have accidentally clicked it.


After the moves 1. ... Kh8 2. Ra1 from your diagram position, the black queen is attacked and the only "safe" squares it has available (where it wouldn't be immediately captured on the following move) are then c5, d6 and e7. The text you quoted is pointing out that no matter which of those the queen might move to, there is a discovered check by the knight which nabs the queen anyway:

2. ... Qc5 3. Nxe4+ (or 3. Nd7+)
2. ... Qd6 3. Nxe4+ (or 3. Ne8+)
2. ... Qe7 3. Nd5+

At best for Black in those lines, he's losing his queen for knight. Because of that, after 1. ... Kh8 2. Ra1, Black could instead bite the bullet and play 2. ... Qxa1 3. Qxa1, hoping to "only" give up queen for rook (and I think that's the line you have in mind at the end of your question). Now as it turns out, from that position Black actually has no way to avoid a further loss of rook for knight (again because of discovered check threats that still remain), and so would ultimately end up with a net loss (starting from your diagram position) of queen for knight in that line too.

[fen "5rk1/pb3p1p/1pr5/8/2P1p1N1/qPQ1P3/4B1PP/3R2K1 w - - 0 1"]

1.Nf6+ Kh8 2.Ra1 Qxa1+ (2...Qc5 3.Nxe4+) (2...Qd6 3.Nxe4+) (2...Qe7 3.Nd5+) 3.Qxa1


No.  It may be difficult to win against a top GM who is playing for a draw, but it's by no means impossible.

If GM's could always draw at will, we could stop all championship matches once either player won a game, since the outcome would be decided.  But we don't do that, because the outcome is not decided after one player gets one win.


The oldest recorded game with the modern rules for moves is this game played in 1475. Although it's not clear if castling and en passant were in force.

[FEN ""]
[Event "Valencia "]
[Date "1475"]
[White "Francesco di Castellvi"]
[Black "Narciso Vinyoles"]

1.e4 d5 2.exd5 Qxd5 3.Nc3 Qd8 4.Bc4 Nf6 5.Nf3 Bg4 6.h3 Bxf3 7.Qxf3 e6 8.Qxb7 Nbd7 9.Nb5 Rc8 10.Nxa7 Nb6 11.Nxc8 Nxc8 12.d4 Nd6 13.Bb5+ Nxb5 14.Qxb5+ Nd7 15.d5 exd5 16.Be3 Bd6 17.Rd1 Qf6 18.Rxd5 Qg6 19.Bf4 Bxf4 20.Qxd7+ Kf8 21.Qd8#

There is also this - http://www.chess2u.com/t8826-oldest-recorded-chess-game - game which is supposed to have been played some time in the 10th century with old move rules. So, no double first move for pawns, bishops moving like a knight (2 squares diagonally but jumping over the intervening square) and possibly other rules for queens for example.


Opening theory versus strong AI suggestions

There are at least four possibilities, all of which are pretty normal.

One, the opening theory is from a good, recent book. The author will have used the strongest engines himself, and also applied his own chess knowledge, and spent enough time to find better moves than the engine did.

Two, the author did see the computer move, but thought it was not practical for a human to play like that, and that his move was almost as good but much easier to understand, explain and play.

Three, the position is drawn (as most opening theory positions are) and in the final analysis both moves will turn out to be good enough.

Four, you've found a mistake in the book.

All of those happen all the time.

If you have a concrete example, you'll get much more concrete responses.