# Question
Title: Is it beneficial to play chess against yourself?
I tried it when I first learned chess, and it was fascinating, because I had no ideas about strategy or tactics. But now that I have some experience, it seems pointless, as I know what my "opponent" is thinking all the time, and what my main ideas are for both sides. Should I still make an attempt to play against myself? Is there a deeper point behind doing so that helps one's chess ability? Do strong player (expert or above) do it?

# Answer
> 21 votes
Depending on exactly what you mean by "playing chess against yourself," I would say it can be extremely beneficial, and that yes, strong players do this quite a lot.

Consider what you do when you have to decide what move to make when you're playing a normal game against an opponent distinct from yourself: you *analyze* the position as best as you can in your head, which means needing to figure out what possibilities are available to *both* players in order to get to the truth of the position. In essence, you play some portion of a game against yourself starting from the position you're at. But you don't just play straight through; you have to consider sidelines and various ideas and pitfalls that might pop up along the way.

Because this is such a fundamental part of playing the game, analyzing positions or entire games on one's own, freely exploring moves and ideas while trying to determine best play, is a fantastic way to improve at chess. Not only does this endeavor have the simple potential to open your mind by exposing you to more and more types of positions and ideas, but it also offers practice at just the kind of thought process that you continually need to engage in internally during a game. One can anylyze existing games, of course, be they grandmaster games or your own past games, but games initiated on the spot serve just as well to offer up new positions in which you have to figure out how to play for each side.

So if, when you play a game against yourself, you don't merely play an alternating sequence of moves until you get a result, but instead do some stopping, backtracking and general meandering, digging deeply to figure out how and why things could proceed differently, then really you're working to develop your analysis skills, and so it could definitely prove beneficial.

# Answer
> 11 votes
If you remain unbiased, playing against yourself will force you to try to find the best (or at least good) moves for both sides. It is actually a stiff mental exercise.

But it gets you thinking, if I do this, what is the other person going to do, and what do I do now, given that the other person has done this.

The danger is that you will get into a "rut" and learn only certain types of positions that you are particularly suited for.

# Answer
> 8 votes
Yes! I find it extremely helpful to play chess against myself. *It is important to remain unbiased.* At any given time, I have a chess board on a table which has an active game usually going for a week or two that I play against myself. Playing against yourself will allow you to consider the tactics of your opponent more thoroughly because when you are playing against yourself, your opponent always knows what you are thinking. This can be important to consider, in that, if I have a forced mate against another player in 5 moves, it really does not matter that we both see it, because in the end, the mate is forced. My point is that even if your opponent sees the correct move coming, that does not diminish the move.

# Answer
> 6 votes
I don't believe it is useful to literally play against yourself. Instead, I'd recommend you spend that time analyzing your OTB losses from the chess club you ought to be attending weekly.

# Answer
> 2 votes
When you analyze a position, you are in essence "playing against yourself", deciding which is the best response to each move. That can't help but be beneficial, if only to enhance your analysis skills. And when you go over a game after it is finished, looking for your mistakes, that's basically what you're doing as well. Strong players do this all the time. As a result, I would consider these forms of "playing against yourself" to be beneficial.

# Answer
> 1 votes
My answer to your question is not an easy yes or no. Yes, it is beneficial to play chess against yourself when you want to reveal your weaknesses, and where you are lacking. No, it is not beneficial to play chess against yourself when you totally know your weaknesses and where you are lacking.

# Answer
> 1 votes
I believe that it is very beneficial to play chess against yourself. If you play without bias and try to make the best move possible on both sides, you would be able to see exactly where your strengths and weaknesses lie.

# Answer
> 1 votes
The best part of playing chess against yourself is when you are trying to learn a specific opening line where you are learn the moves of black and white from both sides.

Secondly, if you are able to dig any weakness of both camps by playing a certain opening.

# Answer
> 1 votes
Composing chess problems is "playing chess against one's self". Trying to find interesting and novel behaviour in the arrangements of pieces. It can be exciting and frustrating, and the feeling when the plan finally comes together into a real position is incredible. The competitive aspect, if one wants it, is that other composers are also searching for cool stuff.

---
Tags: learning
---


# Question
Title: What is the origin of descriptive notation?
Algebraic Notation is the modern standard for recording chess games. It is easily human-readable, yet it can be parsed by computers without difficulty.

Descriptive notation predates algebraic significantly. Essentially all English-language chess literature from 1960 or earlier records moves descriptively. The Wikipedia article doesn't provide sources for who developed this notation or when it emerged. There's an unsubstantiated reference on the Chess Notation Wikipedia page to 18th century usage, and it claims that Philidor's defeat of Philip Stamma stunted the growth of algebraic notation. Hence the question:

**Is there any history as to when descriptive chess notation emerged, and who developed it?**

# Answer
> 8 votes
AFAIK, Edward Lasker (not Emmanuel) Lasker was the only master player resident in the USA to publish in Algebraic before the 1970s, substituting English initials for the German he would have used before immigrating. Not only are Bobby Fischer's books in Descriptive, so are his scoresheets.

I don't know about 18th Century usage, but I have read 19th Century British works that use a descriptive *phrase* like "King to his third square" for K-K3, either Ke6 or Ke3 (the color being obvious by whose turn it is to play). The transition from phrasing to a strictly symbolic Descriptive notation, I can't help with.

# Answer
> 0 votes
Descriptive notation was just the easy shorthand for writing out the moves in detail or even starting to abbrev them until the minimal amount of description remained.

---
Tags: history, notation
---


title: Is Stockfish 11 (level 20) beatable?

text:
# Question
Title: Is Stockfish 11 (level 20) beatable?
I have heard many people saying, “Hah! I beat Stockfish,” and one saying, “I am the best chess player ever! I beat Stockfish.” So I wonder if it is possible, just to know whether I should try to beat it. I tried to play it once; I barely played 25 moves.

# Answer
> 66 votes
The answer is that they either played it on some very handicapped mode, they took back A LOT of moves, or they are probably lying.

Stockfish 11 is currently rated about 3607, and that is in standard chess. Computer programs are typically even HARDER to beat for humans at even faster controls.

There is a reason elite humans have not played matches against computers for a long time: even the Carlsens of the world cannot beat them any more. According to the ELO winning expectancy calculator, there is currently a 745 point difference between Stockfish 11 and Carlsen, and per the chart, that gives the computer a 99.5439696% chance of winning.

Note: The ratings used above are from different rating pools, and thus, are not truly directly comparable, but used as a rough estimate of what would happen between the computer and Carlsen.

# Answer
> 43 votes
It's absolutely beatable, but not by an unassisted human. Anyone who claims to have done so is either lying or stacked the deck super heavily in their favor (e.g., by having Stockfish search only to depth 2). "Slow computer" isn't good enough - Stockfish 11 running on 1999 hardware would still have handily beaten Kasparov. You will need help from another engine to win.

Here's a recent game Stockfish lost to Leela Chess Zero.

```
[FEN "rnbqkbnr/pppppppp/8/8/8/8/PPPPPPPP/RNBQKBNR w KQkq - 0 1"]
[Event "Trillion-Node Throwdown II Tiebreaker (30|5)"]
[Site "?"]
[Date "2020.02.18"]
[Round "1"]
[White "Lc0"]
[Black "Stockfish"]
[Result "1-0"]
[ECO "A41"]
[GameDuration "01:13:46"]
[GameEndTime "2020-02-18T11:44:09.048 PST"]
[GameStartTime "2020-02-18T10:30:22.171 PST"]
[Opening "Queen's Pawn"]
[PlyCount "199"]
[TimeControl "1800+5"]

1. d4 d6 2. Nc3 Nf6 3. e4 e5 4. Nf3 Nbd7 5. Bc4 Be7 6. O-O O-O 7. a4 c6 8. Re1 Re8 9. Ng5 Rf8 10. Nf3 h6 11. h3 Re8 12. a5 Qc7 13. Be3 exd4 14. Nxd4 Bf8 15. Bf4 Rb8 16. Bg3 b5 17. axb6 axb6 18. b4 b5 19. Bb3 Bb7 20. Re3 Ne5 21. Bh4 Nfd7 22. f4 Nc4 23. Rg3 g6 24. f5 Kh7 25. e5 Ndxe5 26. Ne4 Be7 27. Nf6+ Bxf6 28. Bxf6 Qd7 29. Ne6 Rxe6 30. fxe6 Qxe6 31. Qf1 Re8 32. Bxe5 dxe5 33. Rc3 e4 34. Bxc4 bxc4 35. Qxc4 Qd7 36. Qc5 h5 37. Re3 Qd2 38. Qc3 Qd8 39. Ree1 Qc7 40. Qd4 f5 41. Rad1 Kh6 42. Qd7 Re7 43. Qxc7 Rxc7 44. h4 Ba6 45. Rd8 Bb5 46. Kf2 Rf7 47. Rd4 Ba4 48. Rc4 Bb5 49. Rc5 Ba6 50. g3 Bb7 51. Ke3 Rd7 52. Ra1 Kg7 53. Ra7 Kf7 54. Rc4 Bc8 55. Rxd7+ Bxd7 56. Rd4 Ke7 57. Rd1 Be6 58. Ra1 Kd7 59. Ra5 Kd6 60. c3 Bb3 61. Ra8 Be6 62. Ra7 Kd5 63. Rg7 f4+ 64. gxf4 Bf5 65. Rc7 Kd6 66. Ra7 Kd5 67. Ra6 Bd7 68. b5 cxb5 69. Rxg6 Bc8 70. Rg5+ Ke6 71. Rxh5 Kf6 72. Rxb5 Bh3 73. f5 Bg4 74. Kxe4 Bh5 75. Ke3 Be8 76. Rb4 Kxf5 77. h5 Kg5 78. h6 Kxh6 79. c4 Kg5 80. c5 Kf5 81. Rd4 Bb5 82. Rd5+ Ke6 83. Kd4 Bf1 84. c6 Ba6 85. c7 Bc8 86. Rd8 Bd7 87. c8=Q Bxc8 88. Rxc8 Kd7 89. Ra8 Ke6 90. Ra5 Kd6 91. Re5 Kc6 92. Rd5 Kb6 93. Rc5 Kb7 94. Kc4 Ka6 95. Rc6+ Ka7 96. Kb5 Kb7 97. Rc5 Ka7 98. Kc6 Ka6 99. Kc7 Ka7 100. Ra5# 1-0

```

If these people insist they can still beat Stockfish 11 unaided, challenge them to prove it live. You can probably offer them odds of pawn and move and they'll still lose (they won't even draw). If they actually manage to win, it'll be big news. Here's an example of a claimed win from 2011, at a time when computers were already unbeatable by humans. As ChessBase put it, "Believe it or not? Not, of course. Definitely not." Pointedly, the guy making the claim was later convicted of fraud.

# Answer
> 8 votes
People who say they beat Stockfish did it at a low level, with a fast time control so Stockfish could not do its best, and perhaps also on slower computers.

Can Stockfish be beat at high level on fast computer with long time control? Of course, but it would likely take another computer program to do it.

Remember that Stockfish was rated at 3388 as of July 2017 and would be even stronger now.

# Answer
> 4 votes
I would say it is practically unbeatable by a human player when running according to the TCEC hardware, but theoretically, it could be since chess has so many possibilities that we only completely understand it when only 7 pieces are on the board(Endgame Tablebases). Another fact is that these tablebases were created by supercomputers. I am certainly sure that it could be beaten by non-human players especially Neural Networks.

---
Tags: engines, stockfish, computer-chess
---


title: How does Stockfish calculate advantage?

text:
# Question
Title: How does Stockfish calculate advantage?
Recently when I was on Lichess, somebody pointed out in chat that Stockfish calculated advantage based on what it considered as the best move for both sides. However, when we play the best moves (moves suggested by Stockfish), the advantage changes, which means that the advantage cannot be solely calculated assuming best moves.

However, the advantage cannot be calculated based on some kind of weighted mean of the possible moves either since Stockfish clearly spots winning strategies such as 'Mate in n' for sufficiently small n.

To make the previous paragraph clear, assume that white has mate in 1, and assume that white has 2 legal moves. Also assume that if white doesn't play the move of checkmate, then black has a forced move that is also mate. In this scenario, if we were taking average, advantage would be zero since random moves would give 50% win chance for white and 50% for black. However, Stockfish would show #1.

So how does Stockfish calculate advantage?

EDIT : This question is not asking how the engine finds the best moves. I am familiar with the decision tree method that engines implement to do so. The question is about the 'advantage' value that the engine evaluates. @SubhanKhan 's comment clarifies why the advantage value changes after performing the best move. Does the engine evaluate advantage solely based on the best moves then?

# Answer
Good Question! The reason that the evaluation changes when you put in the engine's best moves is because as you do this the computer gets to look deeper into the future. This is the same as if you were thinking for 10 minutes on a position and saw that it was a draw, but when you look for 30 minutes you get to a deeper conclusion realizing that it's actually a draw. Another evidence I have for this is when you let the computer think on a position for a long period of time(say 1 hour) It usually reaches a different evaluation than the initial evaluation. I hope it helps!
> 3 votes

---
Tags: stockfish
---


# Question
Title: Can anyone recommend a positional book focused on preparing pawn breaks?
Feel free to share more than one book. I'm very interested in understanding better those preparatory moves.

# Answer
@Marcelo, it really depends on what you mean by "preparing".

If you mean that VERY specifically "what specific moves" in every case, that is too general, and there are no such books. If you mean that as "how do I play for a pawn break", in general, then you are really just asking about pawn play, and pawn structures.

Here is a fairly complete list of books about opening pawn structures and pawn play, in general.

1. "Chess Structures: A Grandmaster Guide" by GM Mauricio Flores Rios is the single best book on OPENING pawn structures currently out there, but it misses some.
2. "Pawn Structure Chess" by GM Andy Soltis is VERY weak in the analysis, but the general ideas still hold up.
3. "The Ideas Behind the Chess Openings, Algebraic Edition" by GM Reuben Fine
4. "Chess Opening Essentials" by New in Chess Four Volumes cover every opening, but each one is done fairly lightly, so this is a true beginner's guide.

Here is a list of books on general pawn play.

1. “Complete Chess Strategy” volumes 1,2 and 3 by Ludek Pachman. (This teaches about many basic plans, and what you are striving for with your pieces and pawns, especially. This made a light go off in my head, and THIS is what made me a master.)
2. "Winning Pawn Structures" by GM Alexander Baburin
3. "Understanding Pawn Play" in Chess by GM Drazen Marovic
4. "Dynamic Pawn Play in Chess" by GM Drazen Marovic
5. "Winning Chess Middlegames: An Essential Guide to Pawn Structure" by GM Ivan Sokolov
6. "Chess Middlegame Strategies Volume 2" by GM Ivan Sokolov
7. "The Power of Pawns: Chess Structure Fundamentals for Post-beginners" by GM Jörg Hickl
8. "Isolani Strategy: Strengths and Weaknesses of the Isolated Queen's Pawn" by GMs Adrian Mikhalchishin, Alexander Beliavsky, Oleg Stetsko
9. "Understanding Maroczy Structures" by GMs Adrian Mikhalchishin and Georg Mohr
10. And the original book on the subject, but it uses some weird terms: "Pawn Power" by IM Hans Kmoch
> 3 votes

# Answer
> But it is hard to believe there is no chess book just about preparatory moves, especially with the pawns. This is the very soul of chess in my opinion

The reason is that it is a small subject. That is not to say that there are not several excellent chapters in different books dealing with this subject.

Far away the best such is the very first chapter of Axel Smith's excellent "*Pump up your Rating*" titled "*No Pawn Lever - No Plan*". The book is aimed at strong intermediate level players (roughly 2000 rating) for whom developing effective plans is the next step up. Smith starts his book with pawn levers because it is often one of the main areas which weaker players often actively avoid. They try and resolve tension rather than try and create tension to their advantage.
> 3 votes

---
Tags: positional-play, books, pawn-structure
---


# Question
Title: What is it like to be a Twitch chess streamer?
I want to make a Twitch stream channel with my friend, and I want to know what the experience is like. Can explain it better to me or share their knowledge and experience?

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

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

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

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

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

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

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

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

"Tips for becoming a Twitch video game streamer"
> 1 votes

# Answer
For too many it feels like spewing streams into the void with nobody watching. https://news.ycombinator.com/item?id=17541600

Just how many people are out there watching at all? How many streamers are there?

So how does it feel to stream stuff into the great bit bucket of the cosmos? That strictly depends on you and your psychological problems.

Personally I would feel stupid wasting my time doing it.

Twitch.tv is a video-game broadcasting and viewing platform where viewers can "donate" to their favorite players. ... Video game players broadcast themselves playing the game, usually with an audio commentary.

I would feel more stupid wasting my money on it.

Do I have to pay for twitch? Select Subscribe | $4.99 to choose the default monthly subscription fee of $4.99 USD. Or, pick All Paid Tiers to choose the $9.99 or $24.99 payment option and see a list of perks for each subscription tier.Jul 1, 2019
> -3 votes

---
Tags: online-chess, chess-videos
---


# Question
Title: Why did Kasparov avoid the Marshall Attack?(With White)
I read that during Kasparov's long chess career he always avoided the Marshall attack with Anti-Marshalls (h3 and a4). This seems very counter-intuitive to me since the positions that arise from the opening are very double-edged which seem to favor him. I at first thought that it was because he found it hard to get an advantage out of it, but then again he didn't mind facing the Berlin defense to which he basically got no advantage out of. Could someone please help me understand why he never faced the Marshall attack.

**Kasparov avoided the Marshall in classical time format**

# Answer
It comes down to one main thing, but there are other factors that probably played a part too. The main thing is that despite the nature of the Marshall attack, it is considered drawish at the highest levels. At lower levels, of course, it is a double-edged game where anything can happen. And while they are double-edged, white is on the defensive, not where Kasparov liked to be.

There is, clearly, a lot of theory to learn, but it is doubtful that Kasparov was put off by that since he had the reputation as the most prepared player in history at that time.

With the advent of computers, the Marshal has been analyzed to the N-th degree (meaning a lot), and most of the time, black has enough initiative to hold the draw, or better if white is not prepared. Kasparov, being Kasparov, probably felt like "why should I allow that possibility when I can probably play a line that you do not get the initiative, and we keep more pieces on the board, and I can simply outplay you in the long run? I am Kasparov, after all."

Lastly, and I touched on this already, but it is simply not Kasparov's style: He is the player, who loves to play with the initiative, so why play into a line that neutralizes his greatest strength? He did not, and I confirmed that by searching Mega 2020, and you are correct: There is not one game in there where he allowed it, and that includes faster time controls. That is not a practical way to play good chess.
> 6 votes

# Answer
Kasparov is an attacking player. He is not going to go into lines which allow his opponent to attack. Nowhere in Kasparov's repertoire will you find him choosing to defend for material.

He has a much greater advantage just avoiding forcing book lines where his opponent will obviously be well prepared.

Lastly, he is not choosing the Spanish Torture, as the Ruy Lopez is known, to not torture his opponent; let him go free for a measly pawn?
> 2 votes

---
Tags: ruy-lopez, attack, kasparov
---


# Question
Title: Can you recommend a dynamic, concrete, or easy-to-play line against the London System?
I hate playing against the London because it allows 800 FIDE rated players to survive for 50+ moves.

By the way, I play the Grunfeld against d4, the Sicilian Najdorf against e4, and the triangle against most Nf3 systems. I also play the Ruy Lopez and the most mainline e4 lines there are for white.

So do you have a strong, venomous system that combats the London move order? I looked at 1. d4 Nf6 2. Bf4 c5 which I like for Black, but they can play 2. Nf3 first. Any recommendations? I accept fianchettos and systems where the light squared bishop gets developed.

Thanks in advance!

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

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

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

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

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

These won't prevent long games, but it may provide you with positions that you are more comfortable with.
> 3 votes

# Answer
It really depends on what happens after those first few opening moves. London is solid but passive. I have no trouble against it. But you have to respond to the later moves in a way to gain an advantage.

There is no slash and burn sacrifice and attack counter to the london. It is a quite positional game. So take advantage of the white bishop position and whatever other moves white uses.

I would typically play on the Qside instead of a K attack but it all depends what ELSE white does.
> 1 votes

---
Tags: opening, theory, london-system
---


# Question
Title: The difficulty of finding the exact losing move
Are there examples of chess games where the exact losing move has been found only with the help of engines?

Better still, games where the exact losing move cannot be found even by the best current engines?

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

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

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

As for games where the exact losing move cannot be found even by the best current engines - I spoke to a correspondence chess expert recently, and I'm confident they don't exist. Given a decisive game, an expert correspondence chess player will always be able to find the losing move, but it will not be trivial, and a lot of analysis is required.
> 5 votes

# Answer
Yes, but... Nobody will agree on all of them.

If two PERFECT computers played you could not tell the losing move or else it would be the first move. But I suspect a perfect game would be a draw.

The reason why moving loses is a myth is that the game is played by imperfect humans.

THE losing move is the next to last mistake. But what if a mistake confuses the opponent who resigns. What if the so called losing move wins this time but loses against another player in another game.

Except for the grossest of blunders it will be next to impossible to declare ONE move as THE losing move.
> 0 votes

---
Tags: engines, calculation, famous-games
---


# Question
Title: Castling Rules-Does “The king & rook must be on the same rank.”="Only original rooks can do castling."?
According to Wikipedia, one of the conditions of castling is:

> The king and the rook must be on the same rank (Schiller 2003:19).

This is because of a loophole that would occur otherwise:

> Without this additional restriction, it would be possible to promote a. pawn on the e-file to a rook and then castle vertically across the board (as long as the other conditions are met). This way of castling was "discovered" by Max Pam and used by Tim Krabbé in a chess puzzle before the FIDE rules were amended in 1972 to disallow it. See Chess Curiosities by Krabbé.

I understand this rule like this: Only the two original rooks (not promoted rooks) can partake in castling. Is there any loophole in this understanding of mine?

# Answer
No. You got it right.

The King can only castle if the K and R is on its original square and each has never moved, the king is not in check, and the king does not move through a check, and it is your move so you can move.

I remember that puzzle. Guy at worked showed me a mate in one. Which was impossible. I finally guessed he was a true patzer and thought you really could castle with a promoted rook on the king file. So I did that and got the puzzle right.

It was hard to conceive of castling that way but the rules got fixed to make sure it would never happen. As if it could happen in a real game and not a puzzle-problem.
> 2 votes

---
Tags: rules, castling
---


# Question
Title: Searching for a position in the mega database 2020 with ChessBase 15
The setup is ChessBase 15 with the mega database 2020. I look in it for the Najdorf starting position

```
[FEN "rnbqkb1r/1p2pppp/p2p1n2/8/3NP3/2N5/PPP2PPP/R1BQKB1R w KQkq - 0 1"]

```

as follows :

1. I double click the Mega Database 2020 to open it
2. When done I click on filter list, which opens the window :

3. I click on position to get :

4. I click on "OK", and then I get : "No games found".

What am I doing wrong ?

PS : I know that I can play the position and look into reference (after having selected the mega database 2020 as reference database) to get all games having this position, but I don't want to do it that way. (Imagine a position resulting after 32 moves for instances, don't want to play them all.)

# Answer
> 3 votes
I am not sure what you are doing wrong. I get plenty of games that way. It is possible you did a previous search that still has some residual information in the "search mask" (this is what ChessBase traditionally called the search feature).

I will first show you how to do that and get results, and then I will show you one or two better ways. First, as you noted, it is important to make sure that the Mega 2020 database is the "reference database". I am going to include full instructions since you may not be the only person to read this.

To set Mega 2020 as the reference database, right-click on it, and open the properties. Click the the "Reference-DB" box", and click "OK"

Next, rather than set the position in the search mask, I suggest that you open a blank board and enter in your Najdorf position. 1.e4 c5 2.Nf3 d6 3.d4 cd 4.Nd4 Nf6 5.Nc3 a6.

Now, open the search mask, and click "Reset" first, and then "Copy Board". Then click "OK. This returns 200,471 games for me.

That said, I really only use this feature when I am looking for generic positions. For example, all positions with pawns on f2, g3, and h4, etc. If I am looking for all Naijdorfs, there are much better ways to get them.

First, you could use the opening keys, and drill down, and open the specific ECO keys that you are looking for.

Next, from any opening position, you can use the "Find Novelty" function. To use this feature, you right-click the board, and click "Find Novelty" or the shortcut is "Shift+F6" (the picture I added is in German as I took it from the help file...it is hard to get a screenshot because the menu closes). You can then sort by the "Notation" column. For many years, this was the best way, but they have since added a much better way if you are looking for a specific position. You mentioned that you do not want to do this, but I have no idea why that would be. I am still going to add this in for others, who may read this.

Enter the position, and simply click the "Reference" tab. You can then refine it by the next move, or just go down to the games at the bottom, and start clicking. It also gives you information about the scoring percentages, and notable players, who played it. For me, this has become the best way to search for specific positions.

I have also been using this method as I watch the "Method in Chess" videos on chess24.com. GM Dorfman mentions the names of the players when he starts, but often it is hard to know the name he said. So, I plug in the starting position, click "Reference", and if you go in far enough, it has limited the number of names enough that you can pick them out of a list even if you could not spell them, and enter them.

---
Tags: software, chessbase
---


# Question
Title: What was one shortcoming of alpha zero that Kasparov noted?
> I \[Kasparov\] can look at AlphaZero’s games and understand the potential weaknesses. And I believe it has made some inaccurate evaluations, which is natural.

The reason he says that is AlphaZero uses statistics of ALL games to determine piece value.

Which pieces did he specifically mention?

What other shortcomings does alpha zero have that humans could exploit?

# Answer
> 1 votes
First, as great as Kasparov is, compared to AlphaZero, even he is a patzer; so for him to say that he sees weaknesses, he may be correct, but it could also be, simply, that AlphaZero is playing at a level beyond even his great understanding, and with positional/tactical minutia we, humans, have yet to realize are important, or cannot see at all.

In this interview, he only mentioned bishops versus knights, saying:

> I can look at AlphaZero’s games and understand the potential weaknesses. And I believe it has made some inaccurate evaluations, which is natural. For example, it values bishop over knight. It sees over 60 million games that statistically, you know, the bishop was dominant in many more games. So I think it added too much advantage to bishop in terms of numbers. So what you should do, you should try to get your engine to a position where AlphaZero will make inevitable mistakes \[based on this inaccuracy\].

Note: I believe the 60 million games he mentions are all games played against itself as it was teaching itself how to play, rather than a database of human games. After all, Mega 2020, has only 8 million games in it.

I also found this article that Kasparov penned, in which he said:

> But in my observation, AlphaZero prioritizes piece activity over material, preferring positions that to my eye looked risky and aggressive.

Considering the recent question, "Is Stockfish 11 (level 20) beatable?", and that AlphaZero destroyed a recent, although previous, version of Stockfish, I do not believe that you will find any weaknesses that any human will be able to exploit. That will be the domain of the next, stronger, computer.

---
Tags: engines, software, alphazero
---


# Question
Title: What was it that AlphaZero did that dazzled experts?
Wired magazine recently said

> Most remarkably, AlphaZero uncovered new approaches to the game that dazzled chess experts.

Just what was unique about alpha zero that was so dazzling?

# Answer
I could find nothing that would support that statement beyond that it taught itself in a day. This is speculation, but I believe it explains that line in the article.

After researching the author, I found that he is a technology writer, who got a Bachelor of Science from the University of Kent, and later a degree in journalism from University of the Arts London. He currently writes for "Wired", and previously wrote for the MIT Technology Review. Despite that, I could not find a FIDE rating from when he lived in Europe, nor a USCF rating now that he lives in Cambridge Massachusetts.

I get the sense that it could be a "civilian", meaning a guy, who likes chess, but plays chess very casually, who is trying to write an article, and not really understanding the subject fully. It is akin to watching people on TV try to sound like they know about chess.

I think he was simply using his own words to regurgitate the amazement that we chess players all felt when we heard that AlphaZero taught itself in a day, and already could beat the best program, Stockfish.
> 4 votes

---
Tags: engines, software, alphazero
---


# Question
Title: What would chess openings be like without castling and/or the double pawn move?
Chess has a fairly elegant set of rules, but it has two rather ugly "rules hacks" in it:

* Pawns can move two squares forward, but only on their first move, and have the rather ugly rule of *en passant* to get rid of the nasty side effect of having your 5th rank pawns get bypassed.
* Castling lets you move two pieces at once, and has a bunch of rules about when you're allowed to do it.

Now, the usual justification of these is that they make the game go faster. According to this question, the two-square pawn move was introduced because players would begin each game with 1. e3 e6 2. e4 e5 (or similar). Castling was a variation on the "king's leap" many chess variants had. It makes a certain degree of sense--games are meant to be fun, and why not get to the action more quickly?

On the other hand, chess theory has advanced a lot since the 1500s. In modern opening theory, black often forgoes immediate center pawn moves. 1. e3 would likely meet the reply 1... Nf6, not 1... e6. It stands to reason that some of the considerations then may no longer be the case.

So, has anyone ever done any studies into what chess openings would look like without castling, without the double pawn move, or both?

# Answer
Overall, the game would be slower and opening attacks would be more aggressive at times.

The purpose of implementing the double-step was to speed up the game. That way, those pesky pawns wouldn't have to waste so much time, i.e. moves, moving forward to mount an attack or to develop an area of advantage/control. But with the double-step gone, we would have to revert back to the slow way of the ancients.

The double-step is often done on the c and f files to let the knights out without blocking the pawns. Now it would take more time to flesh out that plan, as it would now take two turns to let the knight out onto its most advantageous opening square.

In some semi-closed positions, the double-step is used as an immediate can opener. However, having to move the can-opener pawn two times might give the opponent just enough time to react and defeat, or at least nullify, your attack. A few more draws might result because the position stays closed.

Additionally, in some games, the double-step is used to quickly advance a rook pawn, and break open the enemy's king's encampment. But with it gone, a single step must be done, thereby giving the opponent time to react. Have a look at the below position and deduce for yourself how this affects the game.

```
 [FEN "3r1r2/1bp3k1/1p1qp2p/p2p2n1/5NQ1/PBNP2P1/1PP4P/1K2R2R w KQkq - 0 1"]

```

As for no castling, it would also lead to a slower game, but at the same time lead to more aggressive opening attacks. The concept of castling, even if the move isn't allowed anymore, would still be a popular motif due to how it keeps the king safe.

Doing castling manually takes several moves, and with both players doing so, games would start to be several moves longer. Due to the slow process of doing so, an opponent may try to catch the king in the act and take him down. Kings would be in the center longer, also leading to a reason to favor, and as such an increase, in open positions. That allows for an attack to be done faster. Artificial kingside castling would increase in use due to the process taking much longer than on the queenside.

At the same time, however, with the hindrance of the double-step, such attacks may be also seen less often due to the need to spend time mobilizing pawns. The enemy might use your time to manually castle, ruining your plan.
> 2 votes

# Answer
You would find more slow openings like the hedgehog in reverse.

There would be more fianchettoes and knights on bishop 3. Then k&q on 2nd rank with a rook moved to middle to let the king slide to the side to be safer when appropriate. Might cause delayed castling and affect the choice of side the king runs to.
> 0 votes

---
Tags: chess-variants, castling, en-passant
---


title: Alpha-beta add variance/handicap

text:
# Question
Title: Alpha-beta add variance/handicap
I want to implement a handicap for my engine and I'm struggling with it. I using alpha-beta pruning.

In my current approach I set a variance variable in centipawns and let the engine choose a move in the variance range. An example with white to move and variance = 5;

```
25 d2d4 d5d7 ...
23 e2e4 e5e7 ...
20 b1c3 e5e7 ...
18 g1f3 d5d7 ...
...

```

In this case the engine can choose between the first three moves cause they are all in range of 20-25. A random move of those three is picked, all other moves are ignored.

I implemented this and let it run against my "best move engine". To my surprise in 200 games the "best move engine" wins like 95% of the time. Which is in my opinion way to high.

As I dove deeper I realized that the "variance engine" picks sometimes totally blunder moves. Like sacking a queen without any compensation. I triple checked the code for picking the "random" move in the variance range. Its perfectly fine. So I think my alpha-beta is the problem here. Some questions:

1. Should alpha-beta in general be capable of implementing something like variance picking. If so, what could I have done wrong or what am I missing?
2. Is there another way of implementing a handicap for an engine. Couldn't really find anything on the internet.

# Answer
Even one minor error could cost the game against a perfect opponent, so 95% losing rate is generous. However, I don't understand how the "best move" engine could lose any games in the second trail.

1. The ABSearch could be modified, but it's easier to perform this at the RootSearch function. Since the arrays for the current moves and their respective scores are present here, it's easy to implement, and the RootSearch should be able to self-correct on future moves better than anything done in the current ABSearch. (This is really messy. Sorry.)
2. I've seen three ways to limit strength.

a. Make a weak move at a specific interval. When playing against its sponsors, a computer was told to make a random king move every 10 moves.

b. The computer wasn't allowed to make a move in which the eval was above a threshold. So, for a drawing computer, the computer wouldn't make a move where the eval was above a pawn or had to make a mistake to lower the eval to below this range. This i similar to your variance, but instead of within the top range, it's a final eval of +- a pawn.

c. The chess engine Galahad (I can't find its source anymore.) allowed you to change some eval constants. Lowering the penalty for a weakness, such as doubled pawns, does lower its strength, but not in a dramatic manner.

Trappy Beowulf trys to implement a more human engine where it does try for traps instead of the best move. I haven't read the code, so I can't explain how it accomplishes this, but I assumed that it goes for simple, one move threats, and when this threat is parried, the positions is slightly worse.

I"d like to give a special thanks to the four examples and the OP for thinking out of the box. Not just trying to be the best, but for being usable.

EDIT: A better example is "c" would be a piece-square value. By adjusting this variable, you could make the computer think that g3 is a better square for the knight than e5. This could be used to make the computer decentralize pieces or make them more defensive. Changing the pawn protection around the king values, you could make the computer make these weakening moves and test your attacking skills. The options are only limited by your imagination.
> 1 votes

# Answer
Does not sound to high to me. Actually I would expect higher.

1 Depends on all the other things your code does and how.

2 Some make mistakes at random.

You could limit how far you look into the future too.

Try making 2nd best (or slightly less good) moves but only when there are many closely evaluated ones. Avoid those bad queen sacs by just picking a really bad one when there are not really any other good alternatives.
> 0 votes

---
Tags: engines, programming
---


# Question
Title: Best way to loop through all possible moves (Alpha Beta)?
Essentially I'm just trying to create a somewhat efficient chess ai using an Alpha Beta Pruning approach for a future neural network to train against. I know I could use an existing program but this is a learning experience and I want to write the code for myself. Essentially the entire program is based on this pseudocode for the Alpha Beta algorithm

```
function alphabeta(node, depth, α, β, maximizingPlayer) is
    if depth = 0 or node is a terminal node then
        return the heuristic value of node
    if maximizingPlayer then
        value := −∞
        for each child of node do
            value := max(value, alphabeta(child, depth − 1, α, β, FALSE))
            α := max(α, value)
            if α ≥ β then
                break (* β cut-off *)
        return value
    else
        value := +∞
        for each child of node do
            value := min(value, alphabeta(child, depth − 1, α, β, TRUE))
            β := min(β, value)
            if α ≥ β then
                break (* α cut-off *)
        return value

```

The way I've chosen to represent the game state which I found was both somewhat easy to understand and an efficient manner to represent the boards is as an array of bitboards one for each piece type and color. Creating and organizing this system was simple enough but I can't find an as straight forward answer to the question of a decently efficient but both not incredibly complicated way to loop through all the possible moves. And second, a more accurate and efficient way to determine the score of the board. I can think of ways such as storing the opponent's possible attack points to look for checks but even then looking for a check every time seems very inefficient. In addition to this, I can't conceive a good way to add all the possible moves every piece can take because of all the extra cases. For example, a pawn can move forward or if its the first turn move 2 forward or if theirs a piece diagonal to it it can take it. Hard coding all this would be very disorganized so what I guess what I'm looking for is a system that will work generally but also not be widely inefficient. If anyone has suggestions that would be greatly appreciated. This is a version of my code stripped of all the different experiments I tried.

```
public class Board {
    long[] board = new long[12];

    public Board() {
        /**
         * The board array is a set of 12 bitboards
         * each a different kind of peice and color
         * - Even indexes are white odd indexes are black
         * - The order of peices is order of points
         *   Pawn, Knight, Bishop, Rook, Queen, King
         * - The board is defined in this order (rook or index 6)
         *
         *  8 7 6 5 4 3 2 1
         * -----------------
         *  0 0 0 0 0 0 0 0
         *  0 0 0 0 0 0 0 0
         *  0 0 0 0 0 0 0 0
         *  0 0 0 0 0 0 0 0
         *  0 0 0 0 0 0 0 0
         *  0 0 0 0 0 0 0 0
         *  0 0 0 0 0 0 0 0
         *  1 0 0 0 0 0 0 1
         *
         *  - otherwise described as
         *  0b0000000100000000000000000000000000000000000000000000000000000001L;
         */

        // Pawns
        // White
        board[0] = 0b00000010_00000010_00000010_00000010_00000010_00000010_00000010_00000010L;
        // Black
        board[1] = 0b01000000_01000000_01000000_01000000_01000000_01000000_01000000_01000000L;

        // Knights
        // White
        board[2] = 0b00000000_00000001_00000000_00000000_00000000_00000000_00000001_00000000L;
        // Black
        board[3] = 0b00000000_10000000_00000000_00000000_00000000_00000000_10000000_00000000L;

        // Bishops
        // White
        board[4] = 0b00000000_00000000_00000001_00000000_00000000_00000001_00000000_00000000L;
        // Black
        board[5] = 0b00000000_00000000_10000000_00000000_00000000_10000000_00000000_00000000L;

        // Rooks
        // White
        board[6] = 0b00000001_00000000_00000000_00000000_00000000_00000000_00000000_00000001L;
        // Black
        board[7] = 0b10000000_00000000_00000000_00000000_00000000_00000000_00000000_10000000L;

        // Queens
        // White
        board[8] = 0b00000000_00000000_00000000_00000000_00000001_00000000_00000000_00000000L;
        // Black
        board[9] = 0b00000000_00000000_00000000_00000000_10000000_00000000_00000000_00000000L;

        // Kings
        // White
        board[10] = 0b00000000_00000000_00000000_00000001_00000000_00000000_00000000_00000000L;
        // Black
        board[11] = 0b00000000_00000000_00000000_10000000_00000000_00000000_00000000_00000000L;
    }

    public void generateMoves() {
    }

    public String getBoard() {
        long fullBoard = 0;
        for(int i = 0; i < board.length; i++) {
            fullBoard |= board[i];
        }
        return Long.toBinaryString(fullBoard);
    }
}

```

# Answer
> 2 votes
The questions are difficult to understand, and I assume that you are looking for: 1) A way to loop through moves during the AB search (when in bitboard format).

and

2) How to eval the board in the bitboard format.

The simple answer is to look at the code for Crafty Chess. This is a good and heavily commented source code.

---
Tags: engines, programming, alphazero
---


# Question
Title: Knowing that AlphaZero beat Stockfish 8 (28 wins, 0 losses, and 72 draws), what would AlphaZero's rating be?
I found three different questions here on SEC that asked what Stockfish 8's rating was for the match against AlphaZero, but none that asked what AlphaZero's rating should have been after (if it had been in a rated event, and assuming that it previously had an established, not provisional, rating).

Stockfish 8 was rated 3378 at the time per the official rating list. There was some dispute that it was handicapped, but since we cannot really factor that in accurately, it is better to ignore that for now.

# Answer
> 7 votes
+28, =72, -0 corresponds to a score of 64%.
The FIDE Rating Regulations effective from 1 July 2017 give details for calculating rating differences in table 8.1a. According to that table a fractional score of 0.64 corresponds to a rating difference of 102.

Hence if Stockfishes rating is 3378 then AlphaZero's is 3378+102 = 3480

# Answer
> 8 votes
Here's an online calculator for this. 28 wins, 0 losses, and 72 draws is an elo difference of exactly 100.

Do remember that this score +28 =72 -0 score was against a handicapped version of Stockfish. In the full paper, AlphaZero scored +155 =839 -6, which is an elo difference of 52.

# Answer
> -6 votes
Statistically it should be about 3450 +/- 200 but it depends on the fine print of the rating system.

SEE edit where another site estimates 3750!!

Does game order matter?
Are they all rated as a group at the end?
Are their special rules for rating matches like USCF used to have?

And it depends on how accurate the statistical assumptions the rating system is based on were to begin with.

I love when non statisticians weigh in with nonsense reasons why that number is wrong. Perhaps I should have put a +/- error band on it initially.

From another site I found this estimate I estimate AlphaZero's playing strength at around 3750. Computer ratings are pretty compatible with FIDE, since we know Stockfish can beta Carlsen 3,000 times out of 100, making its 3441 or whatever accurate. ... It was also incorrectly thought that the positional sacrifice had been refuted by correct evaluations, but AlphaZero blew that out of the water. It plays more like Alekhine. Now when I train with Stockfish I don't treat the evaluations as gospel the way I might have before. ... What AlphaZero really shows is the value of othinking for yourself unless you want to be like th ecarbon-copy players who get to 2700 at age 14 and barely 2750 a decade later.

---
Tags: rating, stockfish, computer-chess, alphazero
---


# Question
Title: Can watching grandmasters' games improve my chess 'thinking'?
Can my chess "thinking" (positional, tactical, strategic thinking, etc.) improve by watching grandmasters' games regularly? Of course, this is in addition to regular games/tactics solving etc.

As an example, when learning any foreign language, it's a good practice to watch movies and listen to language as much as possible.

I'm interested in pattern matching, as my brain is very good at it. I think that by constantly watching high-quality games one can develop knowledge of the best moves/strategies/tactics.

Has anyone applied this technique or has an opinion on this? Cheers

# Answer
To get the most from other people's games, it makes sense to look at games that were played well. However, what a beginner needs to see is not perfection, but what happens if one player makes a mistake, and how the other player punishes it. This means either looking at games where only one of the players is a master, or at games played by two masters that were annotated by a master to show what *would have happened* if certain bad moves had been played.

There are quite a few good ways to do this. The most economical use of time is *not* to watch a live game, because this involves long delays, interruptions, and incomplete and erratic delivery of any offered analysis.

Instead, the most economical use of study time on master games is to replay a game that has annotations, ideally accompanied by explanations in English (or some other language comprehensible to the reader). Perhaps the best idea is to find classic games by one of the masters in the Romantic Age of chess that are comprehensively annotated, but almost any master's game should yield benefits.

A word about annotations: Many games are annotated by masters *for masters*. Examples are those analyses that are published in Sahovksi Informator ("Chess Informant"). These contain no words; all games are annotated with only variations and glyphs representing chess concepts, ideas and evaluation results. They would be incomprehensible to a beginner. What I'm referring to are games like those annotated in USCF's Chess Life, or the collected games of a master such as:

* "*My 60 Memorable Games*", Bobby Fischer
* "*Fire on Board*", Alexei Shirov
* "*The Sorcerer's Apprentice*", David Bronstein
* "*I Play Against the Pieces*", Svetozar Gligoric
* "*The Life and Games of Mikhail Tal*", Mikhail Tal
* "*Alekhine's Best Games: 1908-1923*", Alexander Alekhine
* "*Alekhine's Best Games: 1924-1937*", Alexander Alekhine
* "*100 Selected Games*", Mikhail Botvinnik
* "*My Best Games of Chess*", Valeri Smyslov
* "*Capablanca's 100 Best Games of Chess*", Harry Golombek

Another source is Everyman Publishing's "*Move by Move Series*". I would recommend the books in this series on Paul Morphy, Victor Korchnoi, Raul Capablanca, Mikhail Tal, or William Steinitz. They have the advantage of being published in e-book format.

"*The Amateur's Mind*", by Jeremy Silman, approached this technique differently with the (relatively) novel idea of looking at *amateur* games, pointing out their flaws, *why* they were flaws, and what would have worked better.

The other disadvantage of this book is that you won't see an illustration of how to play well, you will only see *some illustrations* of how to play badly.

That said, since the mistakes made by the players involved are common among amateurs, you may realize that you are also making them, and be able to fix them. Another benefit is that the book tries to delve into *why* these amateurs made these particular mistakes; the author tries (though a bit unsystematically) to get to the *root cause*. This may be very illuminating for other amateurs out there.

One final note on Silman's book: Not everyone likes Silman's writing style, which some find abrasive at times, so I recommend that you look over samples of the content in a bookstore, or at your library or chess club. (Somewhat mysteriously, Amazon doesn't seem to offer a preview of this book, as they do with many others...).
> 5 votes

# Answer
Chess "thinking" is first and foremost a skill. As such it has to be practiced actively. Passively acquired knowledge will only flesh out what you already can do, it will not improve your chess all that much.

Of course if you try to follow all the variations of the commentators and constantly come up with variations on your own, you will benefit from watching games, thought the level of these games probably doesn't have much of an influence on the training effect.

Generally improvement happens outside your comfort zone. If it doesn't feel like you put something into it, you probably wont get anything out of it.
> 5 votes

# Answer
Depends on your strength.

If you are able to understand what's going on in the game, then yes. But if you feel like watching a mystery thriller, then no. To learn and improve yourself, first you should understand what's going on.

For example, I would advice 1800+ FIDE players to watch and analyze GM games. And I would advice 1600- players to not to lose time with it.
> 3 votes

# Answer
Well, keeping abreast of current games in current tourneys and trying to play/understand them all is not so useful. Many GM games fizzle out into a draw, because they are based on 20 moves of theory not worth remembering.

There are a lot of chess channels that show a game a day, or a game a week, and they can pick out the most exciting and instructive ones, the ones that help most with the basics. I also like the randomness and not knowing what comes next, as often I'm exposed to an opening I blew off, but I can see its dynamic potential.

I also like to visit chessgames.com for the game of the day, as well as play the daily tactics. The comments there help me see "what if X/then Y" and so forth, which is at least as important as a list of moves, or a GM's analysis. People of a variety of strengths comment, so you get to see a bunch of ideas beyond "oh he got this right" or "oh he messed this up."
> 1 votes

# Answer
Definitely. I played over every game from the 1953 Candidates tournament that had 16 top GMs vying to qualify for the world championship that would find a new champ as the old one had died.

The biggest value was in the openings as I learned every variation of the nimzo as it was one of the most popular openings that year.

But having played thorough every note and variation as well as every game I am sure that I picked up a lot more by osmosis that helped my play.

While there were some interesting tactics, it would help to play over collections of tactics by THEME on a web site. Playing over many of the same theme will fix that pattern into your brain to more easily recognize if it shows up in your games.

Likewise while endings were interesting you really need to devour a good end game book like BCE or whatever else is newer now that might be better.

Fischer and other top grandmasters regularly play over every game in tournament collections to see what they can learn and also for weaknesses they can exploit when they play other people in a tournament.

Based on my experience and what GMs do I have to say that if you play over grandmaster games it has to benefit your play.
> 1 votes

# Answer
Definitely. In my experience, I've had several "aha" moments watching GMs play. At times watching their games, but also hearing them comment and articulate the thought process, allowed me to gain insights that I would never have attained on my own.

One recent example: watching a Nakamura Youtube video when he said in the opening: "What kind of structure do I want to play?" triggered an avalanche of thoughts in my head that amounted to a realization that determining the pawn structure early on is, firstly, in your hands, and secondly, paramount to the rest of the game.

Great question, I definitely agree that getting into the mind of the genius is a great part of the joy of chess.
> 1 votes

---
Tags: learning, training, master-games, preparation, famous-games
---


# Question
Title: Are there any books pamphlets or articles on how to train to play at GM level?
CL&R had an article about how Fischer trained at a spa in the Adirondacks for an upcoming match.

One thing he did was swim and also hold his breath for as long as he could. Not sure that latter was good.

Recent reports have Caruana and Chirila going for long runs, playing tennis, basketball, and also swimming.

Anand does 2 hours of cardio each night to help stop him from dreaming about chess.

Carlsen went to the Olympic center with his father and they had him change his diet. Less orange juice with sugar and substitute a mix of chocolate/regular milk. He also trained by skiing and hired a personal chef to balance his carbs protein, and calcium.

Carlsen even optimized his sitting position.

Further he reduced his schedule to about 7 tournaments a year instead of about 13. And took time off after each to recuperate.

So GMs do many things other than study chess. Are there any books or good articles prescribing what would be best for training our bodies to play tournaments not just learning chess more itself.

# Answer
> 2 votes
I do not think that there are any books devoted specifically to this topic, probably since the subject is not big enough, and most physical training is covered by books devoted to that subject, in general (not with chess in mind). The topic may be touched upon in other books.

For example, probably first to take a modern approach to training the body was Kasparov, and his trainer goes into that in his two-volume series on Kasparov's development. In fact, on the cover of volume 2, you can see a picture of them running. Even so, the book does not spend a lot of time on this aspect as most people are more concerned with the purely chess aspects of his training.

Coaching Kasparov, Year by Year and Move by Move, Volume I + 2 by Alexander Nikitin.

I believe that Botvinnik was probably the first to espouse the benefits of physical training SERIOUSLY, and I have seen this written about in passing, but again, there was not enough material for a whole book.

Here is a nice article on Botvinnik on "Sports Illustrated". It discusses his physical training a little.

Here is another webpage that discusses the training activities of various modern GMs.

Here is another very good article on the subject. "How physical activity can help you play chess better?"

# Answer
> 0 votes
Long time ago (near 1975 ) The Grand Master **Alexander Kotov** wrote two excellent books:

> 1. Think Like a Grand Master and 2. Train Like a Grand Master.

edited: I forgot Play like a Grand Master.

I don't know if there are web copies availabe. I studied the first and was self-promoted from Elo 1870 to Elo 2195 in 1976.

# Answer
> 0 votes
The book ***Why We Sleep* by Matthew Walker** might be relevant. It is about the (immense) benefits of sleep on learning and concentration, and the damage that comes from not getting enough high-quality sleep. Acute or chronic sleep deprivation can have very harmful effects on athletic performance and concentration, and conversely sleep is literally *needed* to consolidate memories and learn skills. It also talks about how the quality of sleep declines with age and how this can be overcome.

On another note, a Botvinnik quote comes to mind: "*If you want to become world champion, never play in open tournaments*." He thought that playing others who were much weaker or stronger than oneself can be detrimental to one's morale and thought process. The old cliche is that to get stronger, one should try to play people slightly stronger than oneself.

As you've noted, cardio exercise seems to be a trend among top GMs. Cardio can induce growth of the hippocampus, which is relevant for short-term memory. Chess learning is very much about the ability to memorize patterns, so cardio exercise is very useful.

Another trend among top "mind-sports" athletes, including high-stakes poker player Jason Koon, is to reduce the amount of refined carbohydrates in one's diet. They are said to impair concentration. Instead, it is better to rely on energy from healthy fats, such as those found in nuts, olive oil, and fish (or, in Carlsen's case, milk).

---
Tags: books, training
---


title: Illegal move or checkmate?

text:
# Question
Title: Illegal move or checkmate?
I was playing chess with an opponent. He had his queen in front of his king. I attacked the queen and he moved her, exposing his king directly to my rook. It was my turn to move, not his. We couldn't decide if this was a checkmate. We know that moving one's king into check is illegal. What happens however, if one removes a piece in front of his/her King and exposes him to checkmate unintentionally, as in this instance? If it's illegal to do this, but the player makes this move anyway, is he required to take back the move and move differently, or does the game automatically end? Thanks in advance.

# Answer
> 9 votes
It was illegal to move the queen here (and any piece in general) if that move put the king in check from another of the opponents pieces.

If the player tried to move the queen here they have to put it back and make a legal move.

Note that in some nonstandard variation most usually of the blitz speed type the special rules allow you to take the king and win if they make that illegal move.

Some other variations may allow claiming a win if an illegal move is made. I have played blindfold games where that illegal move was a loss by the special rules for that variation of chess.

---
Tags: checkmate, illegal-move
---


# Question
Title: Level the field when letting computers play against each other
I just read this question and it made me wonder: when setting up such a game/comparison - shouldn't you try to level the computing capacity field? Or at least limit how much energy each "player" is allowed to use (and then let each team optimize within that limit). Otherwise, isn't it just a matter of building the biggest computer?

# Answer
You absolutely should, which is why the two most important computer chess tournaments (CCC and TCEC) both make all competitors play on the "same" hardware. "Same" in inverted commas because the recent advent of neural-network engines like AlphaZero, which run best on GPUs, meant that it's no longer fair to play on exactly the same hardware for everyone.

You can see the result of not using equal hardware from the 2019 WCCC results, which Komodo won. Komodo is almost a hundred elo behind Stockfish when run on equal hardware (and Stockfish doesn't play in the WCCC, because it's not a commercial engine and doesn't have full-time staff to attend the event).

The situation right now is traditional engines run on the same CPUs, NN engines run on the same GPUs, and whenever traditional engines play against NN engines, they run on consensus fair hardware. "Fair" here is a very controversial word, because there are several different measures of what is fair that I'm glossing over. Suffice to say unless you are a hardware expert yourself, I'd just trust the admins of CCC and TCEC to use something that's fair.

**Edit**: to illustrate the impact of hardware, here's the list of hardware the competitors played at in the 2019 WCCC. Note Jonny ran on 1200 (!) cores, and it just barely edged out Ginkgo, which was running on 1/20 of the cores. In TCEC Season 14, the two engines played with the same hardware in Division 1, and Ginkgo comfortably finished ahead of Jonny in spite of multiple crashes (which happen because Ginkgo doesn't run well at 43 cores; they result in auto-losses).

You can also see that these games were played is Division 1, not even Division Premier. Many of the strongest engines in the world simply don't participate in WCCC. I don't know the exact reasons why, but I'm confident hardware is a major issue for participants. In turn, this lack of participation is partly why the community don't take the WCCC very seriously.
> 6 votes

# Answer
Yes, you are right. So computer competitions will have rules about compute to keep things level. For example the chess.com computer championship uses this specification:

CPU Engines:

* CPUs: 2 x Intel Xeon Platinum 8168 @ 2.70 GHz 33 MB L3
* Cores: 48 physical (96 logical)
* RAM: 256GB DDR4-2666 ECC Registered RDIMM
* SSD: 2x Crucial MX300 (1TB) in RAID1
* OS: Windows Server 2016

GPU Engines:

* GPU: 4x Tesla V100 (64 GB GPU memory)
* CPU: Intel(R) Xeon(R) CPU
* E5-2686 v4 @ 2.30 GHz Cores: 16 physical (32 virtual)
* RAM: 256 GB
> 3 votes

# Answer
There are a number of reasonable things you could set as constant, which is probably why they have experts determine the rules in a fundamentally arbitrary but hopefully fair fashion. Energy is one, but some other options would be:

* Hardware cost.
* FLOPS (floating point operations per second).

I suspect (although my info is limited) hardware cost and energy would help neural network neural based devices, while a flops based metric would benefit classical engines, because GPUs tend to provide great FLOPS/watt and FLOPS/$ -- metrics that CPUs sacrifice for the ability to go (relatively) quickly through branchy logic.

An argument against using a simple metric is that it might induce behavior that doesn't advance the state of the field in an interesting direction. If you ask for performance/watt or performance/$, people start asking questions like "what about an FPGA or ASIC," and eventually it becomes a competition in brute force and low level tuning, rather than interesting new ideas. Plus people wouldn't be able tinker with the engines at home if they needed specific devices to do so.

It is better to have experts in the field push toward interesting results, IMO. Although "energy limited on commodity hardware" might be fun.
> 3 votes

# Answer
It really comes down to the purpose of the event.

If it is a championship that is trying to determine who wrote the best software, and not just the strongest hardware/software combination, then you want to even up the hardware as best as possible so the software is the determining factor. The winner determines the best software.

If it is a demonstration or exhibition match, like the AlphaZero-Stockfish match, or the Kasparov-Deep Blue match years ago, and it is all about just crushing the opponent and winning at all costs, all bets are off, and you can expect to see massive, and outrageous, hardware builds.
> 1 votes

# Answer
Should we limit human players who play by how much they weigh or their IQ?

There is no point in so called 'levelling the field' when computers play each other.

There is much more than building the biggest computer that determines who wins.

Software makes the hardware happen. And how well they came up with the software and how well they determined the algorithms to guide the software as well as practical tricks they use like having table bases or pitting two machines against each other to help them learn faster are more important than the hardware.

Limiting energy would only mean that they would use different compuer chip technology that has nothing to do with chess.

Your suggestion would change what is being optimized and what most people care about are how well the computers play not how much electricity they use.

However since the real concern is the software the latest championship had these rules for software:

The rules for the World Chess SOFTWARE Championship state that competing programs must run on machines with identical hardware specifications.
> -1 votes

---
Tags: stockfish, alphazero
---


# Question
Title: Are there any papers that highlight the problems with rating systems?
Ratings are a paradox. Mathematically they seem to dependent on other factors than ability. Yet people are obsessed with their rating as if it defines them as a person somehow.

Are their any papers that discuss the many problems that all current rating systems have along with their shortcomings and the ASSUMPTIONS that were used in deciding how to create a rating system.

Are there any statistical studies showing the distribution of wins/draws based on rating differences that have been validated and show whether the assumptions used in FIDE tables and other places are accurate?

OTOH Ratings are useful and 'close enough for government work' But they fall far short of what many people believe about them.

# Answer
It's a bit old, but this paper from 1995 by Mark Glickman (creator of the Glicko rating system) discusses some of the rating systems in use at the time, including the ones used by the USCF, FIDE, and the PCA. In it, several issues are mentioned, such as rating inflation/deflation, regional variations in ratings, variations in time controls, and the advantage of White. There's some other interesting stuff in there, like how natural ratings variation means that a stronger player will have a less than predicted actual performance against weaker players.

Not everything in it is still accurate. For example, at one point it states that the USCF rates events in the order they are received rather than the order in which they were played, but currently the USCF will re-rate the more recent event if an older event is submitted to it, so that is no longer a problem with that system. It also states that FIDE has a minimum rating of 2000, and that is no longer the case. The paper also obviously doesn't discuss any of the more recent systems. But it may be a good starting point.
> 8 votes

---
Tags: rating, statistics, studies-published-report
---


# Question
Title: Is it possible to improve the Elo rating system like this?
Since all chess player’s ratings are between 800 and 2900, why don’t we make a new rating defined like this:

New rating = (Old rating – 800) / 2.2

So that all chess player’s ratings would be between 0 and 999

Or if we would like to be able to easily convert between old and new ratings we could define the new rating like this:

New rating = (Old rating – 1000) / 2

(Though here extremely weak players would have a negative rating.)

My point is that we would have almost the same precision, but we would only need to use 3 digits instead of 4.

I believe the current rating system is bad because a big range of numbers (3000 to 9999) isn’t used.

What do you think? Is there something obvious that I missed or am I really right?

# Answer
> 5 votes
Sure, you could compress the current range like that. The issue, though, is that ELO is *not* an objective scale with absolute endpoints. It's only a measure of play strength relative to past opponents.

The fact that no current player has an ELO above 2900 does not mean that such ratings are impossible. Until 1990, no one had a rating above 2800. In fact, there's no mathematical upper bound on ELO rating at all: see this question, for example. The "big range of \[unused\] numbers" is infinite.

So yes, you *could* compress the ratings--but what do you do when someone achieves ELO 3001 in the uncompressed system? Recompress it with a different scaling factor, and change what everyone's ratings mean? And keep doing this every time someone "breaks" your current system? If the goal is to make ELO simpler to keep track of, this seems rather counterproductive. I suppose you could report `log ELO` to make it more tenable (also sillier), but the fact remains that there's no mathematical bound, so there's no guarantee that all ELOs will stay within the range you're looking for.

---

Perhaps the most pertinent question of all is, *why*? What do you gain from compressing Elo down to three (ish) digits? It diminishes (slightly) your ability to distinguish between players of similar ratings, but what is the upside? Or, why not compress it down to between one and one hundred, or zero and one? It's all the same values; "three digits" is quite arbitrary, and I can't think of any way that it "improves" on the current system.

# Answer
> 5 votes
Re-scaling the rating system doesn't improve it: it just changes the numbers. So what if the world's best players are rated 950 instead of 2900? It's like quoting somebody's mark in a test as 18/20 instead of 90%. The rating system would behave in exactly the same way.

# Answer
> 2 votes
I suppose it is possible to change the rating scale. But, not all players are necessarily between 800-2900. I've seen plenty of players that have a rating below 800. In the last tournament I played, I saw a kid ranked 111 (who one round happened to beat a 500-600).

I don't think it is desirable to have players ranked negative, so let's just say we take the current rating and divide by 2.9 instead. It's also not guaranteed that players will always be ranked less than 2900, in fact, it is likely we will see a player achieve that rating soon. Magnus Carlsen's peak rating was 2882 and not too far in the past no player had achieved 2800. But, for us regular players we would see ratings in the range 0-999.

Other nations have different rating systems on a different scale. The English rating system would rank a 2000 USCF player around 175 ECF. Personally, I like a little more resolution in my rating than that, but the scale is mostly arbitrary. In the end, you either have a bit more precision or less digits. Either way is not too difficult.

# Answer
> 0 votes
No.

That is not an improvement just a scale change.

What would improve it is requiring people to play more frequently or lose points and also normalizing the average every 6 months or more so that the average is always at a fixed number.

I used 2000 as the average in the 60s when I was doing ratings and the ratings went from 0 to 4000. Nobody ever got close to zero and nobody got close to 4000 so that worked well for us.

---
Tags: rating, elo
---


# Question
Title: Ranking systems that take into account the size of the victory
I run competitions, not in chess, but my question relates to chess Ranking systems, and will give an example of the issue I face. Game 1:

Alice scores 5, Bob 4, Chris 3.

I use the glicko-2 and elo Ranking system to break that down into two wins for Alice (over each other player) and one win for Bob (over Chris).

My problem is that if the result was:

Alice 10, Bob 4, Chris 3

That is a much bigger win for Alice, but the ranking system sees the result as no different from the first.

Has anyone come across a ranking system that takes into account margins of victory etc.?

# Answer
If you're interested in use (more than in development), you should give a try to rankade, our ranking system that features rankings, stats, and more.

Rankade doesn't use **Elo**, but its algorithm (called **ree** algorithm), although more complex, is similar to Elo if you play 1-on-1 matches only.

Opposite to Elo and **Glicko** (here's a comparison), rankade can manage any kind of match (one-on-one, faction vs. faction (two teams, which may be asymmetrical), **multiplayer**, multi-faction, cooperative games, single player games, and so on), so you can insert *one* match with *Alice 5, Bob 4, Chris 3* output (without breaking down one actual match in multiple *fake* matches). Anyway, rankade - like all aforementioned ranking systems - does *not* incorporate margin of victory (even if you can easily manage this issue using *weight feature*, and/or insert scores for stats).
> 2 votes

# Answer
I think what you should do is, treat every pair of players like they played a match, and arrived at the given result. So for example in the second case:

Alice vs Bob 10-4 - 14 games

Bob vs Chris 4-3 - 7 games

Alice vs Chris 10-3 - 13 games

And calculate rating like that Although this will distort the ratings, because every point is counted double the times, more if there are multiple players. I think you can weight that in in the k factor in case of ELO, or you can just divide all the games and points with two - this should not be a problem, since performance is calculated from percentages, so a half game can be fine mathematically.
> 1 votes

# Answer
Yes. But it depends what the competition is.

Vegas and all bookies use point spread or dollar odds to make bets come out even. They start with their estimates (unpublished) of the rankings of the teams.

Baseball has its own rankings which depend on the pitchers for the game.

You can (or used to) be able to see power rankings that were published. USA today used to (may still) print the power rankings for college football teams and also for basketball.

The guy who provided them had a system and I saw it described once.

Note that for football the ratings gain less the bigger the win is so that running up the score is not helpful for getting a bigger rating. This is to keep the power rankings meaningful as the football probability of a win depends on the difference in the power rankings. EG if one team is favored by 20 points they are 99% likely to win, if the spread is 3 points then it is about a 55% chance for the higher to win.

You should look at sports gambling and see how they do power ratings for something similar to the type events you are interest in.
> 0 votes

---
Tags: rating, elo, glicko
---


title: Queenless Imbalanced Middlegame

text:
# Question
Title: Queenless Imbalanced Middlegame
I was analyzing the following position for one of the correspondence games that I am playing. In the position, white is up 2 pawns and with my limited understanding, I can't see any real compensation for black. I checked with Stockfish 10 at depth 29 and it evaluated the position as +0.63. I also checked with Komodo 13.2 which gives the position as +0.50 at depth 25. My question is basically on what is the compensation that black has for the 2 extra pawns or is there, in reality, no compensation and I didn't let the computer go into a higher depth.

Here is the position(Black to move):

```
[fen "r1br2k1/pp3pbp/6p1/4P3/5P1P/2N1P3/PP4P1/R1B1KR2 w - - 0 1"]

```

# Answer
> 10 votes
First, I don't think that there is any doubt that black has significant compensation, but clearly, black is still trying to hold this, not win it when talking two computers playing each other. I believe that between two humans, I would probably prefer black.

If you have an eval that says +.63 for white, but black is down two pawns, you have to realize that it means that black has roughly 1.37 in positional compensation.

White obviously has the two pawns, but black has the two bishops in a relatively open position, is ahead in development with the Rd8 already controlling the file, and h4 is a target that at the very least can be used to gain a tempo. Lastly, the g4 square is a wonderful spot for the Bc8, and helps control the open file. Also, the Rf1 is poorly placed, and the Bc1 currently does not have a bright future. One of the extra pawns, although I am going to trade it off, is currently doubled.

I analyzed this using a computer, and it is a VERY difficult position to get a handle on because so many of the moves are almost equal in the evaluations. In each case, what I did was let it get to a depth of 33-37 using Stockfish 11, and then I would advance the game by a move and force in the best move, and then let it get to a depth of 33-37 again, and so on. So, by the time I got to the 16th move of the variation, it was still looking 35+ ply ahead.

Here is the variation I found, and I have notes as to why the moves are being played. At the end, it is still only +.41, and despite the two pawns minus, it is hard to believe that white can win due to black's incredible activity, and the Kg8 will enter the game soon.

```
 [FEN "r1br2k1/pp3pbp/6p1/4P3/5P1P/2N1P3/PP4P1/R1B1KR2 b Q - 0 1"]

 1... f6 2. e4 Bg4 3. e6 (3. exf6 Bxf6 4. g3 Bxc3+ 5. bxc3 Rd3 6. Kf2 Re8 7. e5 Rc8 {and black is almost winning...f5 is already the only move so white can play Bf4 next defending g3.}) Bxe6 4. Kf2 Rd3 (4... Bg4 5. Be3 Rd3 6. Rfe1) 5. Rd1 (5. Be3 Bg4 6. Rac1 Re8) 5... Rxd1 6. Nxd1 Rc8 7. Nc3 f5 8. e5 Bf8 {Ba3 threat.} 9. Bd2 a5 {Idea a4-a3.} 10. Ke1 {To prophylactically protect the Bd2 after a4; Na4 Rc2} Bc5 11. Rd1 Be7 $1 {Only after a2 is undefended does this combined with a4 work.} 12. g3 a4 $1 13. Nxa4 (13. a3 Bb3) 13... Rc2 14. Rc1 Rxc1+ 15. Bxc1 Bxa2 16. Nc3 Bc4 $14 {Nd1 +.41.}

```

# Answer
> 7 votes
The formula for winning a position at this stage of the game when you are 2 pawns up goes like this:

1. Swap the pieces off, or at least enough to make stage 2 possible
2. Create a passed pawn
3. Queen the pawn

The problem here is that white is struggling to complete development and black is the one who has all the control.

* Black controls the open d file
* Black can control the d1 square next to white's king by Bg4
* Black controls the white squares
* Black's g7 bishop potentially controls the a1-g8 diagonal and if the f7 and e5 pawns are exchanged then this could be very painful for white
* Black's development is almost complete while it is hard to see how white can get any of his pieces to good squares any time soon without losing material. The white queenside rook and bishop don't look like they are going to be playing an active role for a while.

In short, white is probably going to have to give up material just to get to stage 1 alive. The question remains can white complete stage 1 and still have prospects of stage 2, creating a passed pawn? The low evaluation of about 0.5-0.6 suggests that there are some chances but everything is still to play for.

# Answer
> 2 votes
First of all, white's pieces don't have much mobility. The B has one legal move, the queen's rook also only has one move, the king's rook only has four moves and none of them are particularly good. The king is kind of in the way. White is going to have to spend some time coordinating his pieces.

Second, black has the two Bishops.

Third, white's pawns are doubled and there is no clear way to advance them in the short term.

There isn't not enough compensation for two pawns but certainly black's more active position is worth at least a pawn, maybe a little more and that's what the engines are saying.

# Answer
> -1 votes
When you get those results from an engine that shows the game is essentially even while you see a two pawn difference then that means you do not fully understand the value of positions.

Black has the two bishops. With Bg4 he will control the file his rook is on and finish his mobilization.

White will have problems getting his pieces onto useful squares. The white bishop is bad as whites pawns block the bishop

Black will double rooks on the queen file threatening a pawn and the bishop if white moves it to d2.

p-f6 will be double edged freeing the black bishop but giving white a potential passed pawn in the late endgame. White could advance the behind 3 pawn to reblock the bishop. black should wait on that move until rooks and other bishop are deployed.

Overall it is a tough position with a lot of play and white has a minimal edge that might matter between computers but not so much between people who actually do the moves.

If you are black I suggest you offer a draw. Especially since you have been getting outside help by posting the question about an ongoing ICCF game online. If you are white I suggest you offer a draw and hope black takes it.

---
Tags: engines, analysis, middlegame, evaluation, sacrifice
---


# Question
Title: Chess Position Trainer on Linux or Minimax on Linux
Chess Position Trainer allows you to do leaf node evaluation and then minimax the results after that. Is it possible to install Chess Position Trainer on Linux? (I tried under mine, but couldn't), or is there any other software for Linux that can do minimax nodes?

# Answer
> 4 votes
Sorry, no. Chess Position Trainer only runs on Windows 7, 8, and 10.

See the system requirements here.

You could consider a virtual machine running Windows on a Linux host, but it will not run natively.

# Answer
> 4 votes
I have not tried it, but you might be able to install Chess Position Trainer under Linux using WINE. I haven't looked at WINE in a long time, but it's apparently a lot better than it was ~10 years ago when I last tried to do anything with it.

# Answer
> 0 votes
There are oodles of programs for linux. Take your choice.

Stockfish runs on linux. And many other places too. It is open source so you can modify the code to do what you want.

These are rated 'best' chess aps for Linux: PyChess Advanced chess client following the GNOME Human Interface Guidelines /////

Cute Chess Graphical user interface, command-line interface and library /////

Raptor Chess interface for freechess.org (FICS) /////

Stockfish Strong open source chess engine /////

Crafty Highly competent chess engine /////

Scid Shane's Chess Information Database /////

SOSS Chess pairing software /////

ChessDB Based on Scid with some enhancements /////

Jin Java based graphical client for internet chess servers /////

jose Database with a graphical front-end for viewing and editing games /////

Knights Chess game for the KDE desktop environment /////

Xiphos UCI chess engine with modern search techniques and multithreading /////

SCID and ChessX run on Linux as does SCIDvsPC

There are many fine engines for LINUX. Stockfish and Critter are popular with one reviewer.

---
Tags: linux, minimax
---


# Question
Title: What is the longest current tablebase mate with a unique optimal line?
Having been inspired by an article on ChessBase.com, what is the longest current tablebase mate with a unique optimal line?

By unique, I mean for each of the winning side's plies, there is only one move that gives a shortest forced mate. and for each of the losing side's plies, there is only one move that gives a longest forced mate.

# Answer
Guy Haworth gives an answer to this in his Chess Endgame Records.

```
[fen "8/8/7p/7n/k7/8/2K5/3R4 w - - 0 1"]

1. Rd4+! {dtc/m/z = -26/-49/-17m} Ka3 2. Kd3! Kb3 3. Rd6! Kb4 4. Kd4! Nf4 5. Rb6+! Ka5 6. Rf6! Ne2+ 7. Kc4! Ng3 8. Rg6! Ne4 9. Kd4! Nd2 10. Rg2! Nf3+ 11. Kc5! Ka6 12. Rg6+! Kb7 13. Kd5! h5 14. Rh6! h4 15. Rf6! Ne1 16. Rf1! Nc2 17. Rb1+! Ka6 18. Rb2! Ne1 19. Ke4! h3 20. Rb1! Nc2 21. Kd3! Na3 22. Ra1! h2 23. Rxa3+! {KRKP: dtc/m/z = -3/-15/-3m} {Nalimov and Lomonosov DTM EGTs} *

```

Haworth states that this is the longest-known decisive AUMS, Absolutely Unique Move Sequence, known to the author.

This move-sequence arose from White and Black adopting the following strategies. White's strategy is: first, preserve the value, i.e. keep the position won for White; second, maximize DTM. (Why "maximize" and not "minimize"? I don't know, but in the above line White has only one value-preserving option at each move anyway, so it doesn't matter.) Black's strategy is to challenge White to find the unique value-preserving move.

Every move in the above line is optimal for the player's strategy. In the cases of Black's 20th and 22nd moves, there is not one unique option which is optimal for Black's strategy, but for all Black's other moves the move given above is Black's only option which implements Black's strategy of giving White only one option which keeps the position won for White.

Note that the identity and length of the longest decisive AUMS depends on what White's and Black's strategies are. Black's strategy of preferring "restrict White to a unique winning move" seems calculated to enable there to be long AUMSes. If, instead, Black adopts the strategy "maximize DTM", then the game proceeds differently. 18...Ne1 is indeed Black's only option which gives White only one winning move, but it loses in 20 moves. By contrast, 18...Ne3 loses in 32 (i.e. keeps Black alive for 12 moves more); 19. Kc6 then wins in 32, and 19. Kc5 in 34.

Some of the jargon explained:

decisive: ending in checkmate, not in stalemate

AUMS: Absolutely Unique Move Sequence

DTC: depth to conversion (i.e. depth to capture, promotion, or the end of the game)

DTM: depth to mate

DTZ: depth to changing which ply is the earliest at which a 50-move-rule draw may be claimed (i.e. depth to capture, pawn-move, or the end of the game)

value: whether the position is (with best play) won for White, won for Black, or drawn

Upper-case DTC/M/Z refer to white; lower-case dtc/m/z refer to Black.

Depth is measured in plies, where a ply is either a white move or a black move.

Haworth cites Conrady, 2003; van der Heijden #70232, (2010). The relevant entries in his bibliography are:

Conrady H. (2003). Computerschach und Spiele, Vol. 2, No. iv-v

van der Heijden, H. (2010). http://www.hhdbiv.nl/. ENDGAME STUDY DATABASE IV

The longest AUMS I can see in Haworth which ends with the mating move is a 13-ply KNkp mate. Using Nalimov I have extended it back for a further two plies but only by dint of captures.

```
[fen "8/8/8/1p6/b1R5/8/N7/k1K5 w - - 0 1"]

1.Rxa4! bxa4 2.Nb4! a3 3. Nc2+! Ka2 4. Nd4! Ka1 5. Kc2 Ka2 6. Ne2 Ka1 7. Nc1 a2 8. Nb3#! {Nalimov and Lomonosov DTM EGTs} *

```
> 4 votes

# Answer
Any position with seven pieces or less qualifies as tablebase position. Chess composers call composed positions with seven or fewer pieces "miniatures". By looking for “miniatures” in the Die Schwalbe Chess Problem Database, I found new records.

Here is the longest unique tablebase mate. It has a length of **39 plies.**

```
[Title "Victor Cuciuc, E191 diagrammes, 8/5/1984, Mate In 20 Moves"]
[FEN "8/P7/8/8/8/n6q/2p2K2/r6k w - - 0 1"]

 1. a8=Q+ Kh2 2. Qb8+ Kh1 3. Qb7+ Kh2 4. Qc7+ Kh1 5. Qc6+ Kh2 6. Qd6+ Kh1 7. Qd5+ Kh2 8. Qe5+ Kh1 9. Qxa1+ Nb1 10. Qa8+ Kh2 11. Qb8+ Kh1 12. Qb7+ Kh2 13. Qc7+ Kh1 14. Qc6+ Kh2 15. Qd6+ Kh1 16. Qd5+ Kh2 17. Qe5+ Kh1 18. Qe1+ Qf1+ 19. Qxf1+ Kh2 20. Qg2#

```

For six pieces, this is **31 plies.**.

```
[Title "Johannes Steinmüller, Schach 12/1996"]
[FEN "8/3p4/8/8/8/p1p5/2K5/k4N2 w - - 0 1"]

1. Ng3 Ka2 2. Ne2 Ka1 3. Nc1 d5 4. Ne2 Ka2 5. Nxc3+ Ka1 6. Ne2 Ka2 7. Nd4 Ka1 8. Nc6 Ka2 9. Nb4+ Ka1 10. Kc1 d4 11. Nc2+ Ka2 12. Nxd4 Ka1 13. Kc2 Ka2 14. Ne2 Ka1 15. Nc1 a2 16. Nb3#

```
> 0 votes

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Tags: checkmate, tablebases, records
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# Question
Title: Chess.com's daily problem-Why doesn't 1...Nf8 win the Nh7?
Shouldn't 1...Nf8 win here too? Why not?

```
[FEN "r2qk2r/pp1nnp1N/4p1pQ/3pP3/4b1PP/P1B5/1PP1B3/R3KR2 b Qq - 0 1"]

1...Nf8??

```

# Answer
Frankly, you overlooked a major detail...Nf6+ in reply is mate. It is important to notice your "opponent's" moves too.

```
 [FEN "r2qk2r/pp1nnp1N/4p1pQ/3pP3/4b1PP/P1B5/1PP1B3/R3KR2 b Qq - 0 1"]

 1... Nf8 $4 (1... Ng8! 2. Qg7 (2. Nf6+ Qxf6 $1) 2... Qxh4+ 3. Kd2 Qxh7) 2. Nf6#

```
> 19 votes

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Tags: analysis, tactics, puzzles
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