# Question
Title: THE longest problem ever (much longer than the mere 549 mover...)
The *"Fireside Book of Chess"* by I. Chernev and F. Reinfeld includes the following diagram

```
[fen "3nk3/3NN3/3PP3/3BB3/3PP3/3PP3/3PP3/2RQKR2 w - - 0 1"]

```

> Composed by J.N. Babson for Brentano's Chess Monthly in 1882. Mate on the 1220th move, after compelling Black to make three successive and complete Knight's tours.

(Note that there is a mate in one. The problem asks for something more specific.)

Facts:

* Babson is a real composer, famous for long mate problems.
* Brentano's Chess Monthly was a real publication from 1880 to 1882, and Babson did have problems published there.
* A FIDE page that lists people with FIDE titles has a biographical sketch of Babson citing a 1220 move problem, and a 1990 move problem on a 10x10 board.

Issues:

* I can't find any reference to this problem on the web, other than the above mentioned book.
* Nobody ever mentions any problem with this many moves... anywhere!
* A knight tour is the motion of a knight through all the board squares. Three of these would mean only 192 moves.

So here are my questions:

> 1. Is the problem for real?
> 2. How should one interpret the knight tour condition? Probably the knight will capture most of the central pieces, but do the other pieces have to move aside to let the knight through?
> 3. What is the solution?
> 4. Why is this not more widely known?

# Answer
> 14 votes
After some searching, it turns out that this monster is very much a real chess problem. The official name for it is "The Obelisk."

The earliest known reference I have found is from February of 1882, mere weeks after its publication. Bizarrely, it comes from an Australian magazine. The site I found it on is trove.nla.gov.au.

It appears in the February 25th, 1882 edition of the South Australian Weekly Chronicle, published in Adelaide, on page 25. It is part of an overall review of Brentano's January 1882 issue.

Here is a clipping of the relevant section to read for yourself.

I also found mention of it in the "American Chess Review, Volume 1, Issues 1-6"readable on Google books. It is dated to 1886, four years later.

The information is given in the middle of the page. The position itself is given near the end of the page in descriptive notation. More about what that is on Wikipedia. For your information, the "S" is the German notation for the knight; it was semi-standard back then.

Here are later sources.

> Chess Review 1936, issue 37 page 17; viewable online in the US Chess Federation's online archive
>
> Curious Chess Facts, by Irving Chernev, 1937
>
> Wonders and Curiosities of Chess, page 205, by Irving Chernev, 1974
>
> The Complete Chess Addict, by Mike Fox & Richard James, 1987
>
> The Even More Complete Chess Addict, by Mike Fox & Richard James, 1994

Unsurprisingly, there is no solution given anywhere at all. The reason for this is that the magazine ceased publication soon after the mate in 1220 was printed. Thus, another edition with the solution was never made.

As for how to interpret the stipulation, I believe it is very simple. White forces the Black knight to visit each and every square three times. Then White gives checkmates. Most of the moves come from White's pieces dancing around to do said forcing. If anyone is crazy enough to try and solve it, they will surely find a much shorter solution than whatever Babson had in mind.

However, when it comes to solving the problem, I have found a sequence that allows for all of White's pawns to be promoted. This is surely more than enough force for the whole solution for whosoever seeks to truly solve it.

```
[FEN "3nk3/3NN3/3PP3/3BB3/3PP3/3PP3/3PP3/2RQKR2 w - - 0 1"]

1. Nf6+ Kf8 2. Nh7+ Ke8 3. Qa4+ Nc6 4. Qb5 Kd8 5. Qb6+ Ke8 6. d7+ Kxe7 7. Bf6+ Kd6 8. Qa6 Kc7 9. e5 Kb8 10. Qb6+ Ka8 11. Qb5 Ka7 12. Ra1+ Na5 13. Bc4 Ka8 14. e7 Ka7 15. d5 Ka8 16. e8=Q+ Ka7 17. Qh5 Ka8 18. d6 Ka7 19. Be6 Ka8 20. d8=Q+ Ka7 21. Bc8 Ka8 22. e6 Ka7 23. d7 Ka8 24. e7 Ka7 25. d4 Ka8 26. d5 Ka7 27. d6 Ka8 28. e4 Ka7 29. e5 Ka8 30. e6 Ka7 31. d4 Ka8 32. e4 Ka7 33. d5 Ka8 34. e5 Ka7 35. Qh8 Ka8 36. e8=Q Ka7 37. Qeg8 Ka8 38. d8=Q Ka7 39. Qdf8 Ka8 40. e7 Ka7 41. e8=Q Ka8 42. Qeg6 Ka7 43. e6 Ka8 44. e7 Ka7 45. e8=Q Ka8 46. Qee6 Ka7 47. d7 Ka8 48. d8=Q Ka7 49. d6 Ka8 50. d7 Ka7 51. Qde8 Ka8 52. d8=Q Ka7

```

# Answer
> 6 votes
To force the knight into a corner a piece must be sacrificed. 3 knight tours, 4 corners per tour, so that's 12 White pieces that must be lost. And none of the lost pieces can be knights (from where did it get there to give check?).

# Answer
> 3 votes
Looking at the position and the phrasing of the question, I would have to say that the problem is flawed. The directions are far too restrictive - how can white compel black to make three knight tours? If this was defined as a helpmate that's solvable in 1220 moves, then the problem would make more sense. However, even in this case, I cannot fathom how that would be possible as the number of moves that a three knight tours sum to is far less than 1220.

---
Tags: history, problems
---


# Question
Title: Is this the quickest way to clearing the board to two kings?
Is 21 moves the least needed to get board down to 2 kings?

```
[FEN ""]
1. e4 d5 exd5 Qxd5 Qh5 Qxa2 Qxh7 Qxa1 Qxh8 Qxb1 Qxg8 Qxb2 Qxg7 Qxc2 Qxf8 Kd7 Qxf7 Qxc1 Ke2 Qxd2 Kf3 Qxf2 Ke4 Qxf1 Qxe7 Kc6 Qxc7 Kb5 Qxc8 Qxg1 Qxb8 Qxh1 Qxa8 Qxh2 Qxa7 Qxg2 Kd4 Qd5 Kxd5 b6 Qxb6 Kxb6

```

# Answer
Samuel Loyd found faster in 1895.

```
[FEN ""]
1. c4 d5 2. cxd5 Qxd5 3. Qc2 Qxg2 4. Qxc7 Qxg1 5. Qxb7 Qxh2 6. Qxb8 Qe5 7. Qxc8+ Rxc8 8. Rxh7 Qxb2 9. Rxh8 Qxa2 10. Rxg8 Qxd2+ 11. Kxd2 Rxc1 12. Rxg7 Rxb1 13. Rxf7 Rxf1 14. Rxf8+ Kxf8 15. Rxa7 Rxf2 16. Rxe7 Rxe2+ 17. Kxe2 Kxe7

```

https://pdb.dieschwalbe.de/search.jsp?expression=PROBID=%27P0001931%27

This is 17.0 moves.

It is also possible to do it in 16.5 moves but I can't find it yet. See François Labelle's page.
> 13 votes

# Answer
I found the solution to the 16.5 massacre proof game that Remellion mentioned that Francois Labelle had found using a computer search! Well to be more accurate, I found a computer program that found the solution. But it is amazing nonetheless!

I discovered the Jacobi Fairy Chess Helpgame solver, made by Francois Labelle himself. Here is the code that you can use yourself to find all 25 possible games that end on this position: stipulation dia16.5 forsyth 8/5k2/8/8/8/8/5K2/8. It does take around 15 minutes to complete, however.

Here is one of the many solutions.

```
[FEN ""]

1. e4 d5 2. exd5 Qxd5 3. Bd3 Qxa2 4. Bxh7 Qxb2 5. Rxa7 Qxc1 6. Rxb7 Qxb1 7. Qxb1  Rxh7 8. Rxc7 Rxh2 9. Qxb8 Rxg2 10. Rxe7+ Kxe7 11. Qxc8 Rxg1+ 12. Rxg1 Rxc8 13. Rxg7 Rxc2 14. Rxg8 Rxd2 15. Rxf8 Rxf2 16. Rxf7+ Kxf7 17. Kxf2

```
> 3 votes

# Answer
No, that is not the quickest way.

The problem is that you have too many checks. The solution I came up with is to switch to using the rooks to eat pieces. This allows the board to be cleared in 18 moves:

```
[FEN ""]

1.e4 d5 2.exd5 Qxd5 3.Qh5 Qxa2 4.Qxh7 Qxb2 5.Qxg7 Qxb1 6.Qxg8 Rxg8 7.Rxb1 Rxg2 8.Rxb7 Rxf2 9.Rxc7 Rxd2 10.Rxa7 Rxc2 11.Rxa8 Rxh2 12.Rxb8 Rxh1 13.Rxc8+ Kd7 14.Rxf8 Rxg1 15.Rxf7 Rxf1+ 16.Kd2 Rxc1 17.Rxe7+ Kxe7 18.Kxc1  *

```
> 2 votes

---
Tags: theory, problems, records, kings
---


# Question
Title: Longest sequence with only moves to draw without a repetition
What is the longest known sequence of moves with upto 6 pieces where each move of both sides is the only move drawing the game (any other move would lose the game) ?

There should not occur any repitition of a position.

I experimented with the endgame rook vs two (three) pawns and got some sequences I unfortunately do not remember.

# Answer
> 3 votes
To get the ball rolling, from the following position the first 6 moves for each side are forced in order not to lose. (If `7.h8=B` weren't available and `7.h8=Q` needed to be played, then the forced follow-ups `7...h1=Q+ 8.Qxa1+ Kxa1` would extend it to 8, but no cigar.)

```
[FEN "K5R1/8/p7/8/8/7P/8/1q1k4 w - - 0 1"]

1.Rg1+ $1 Kc2 $1 2.Rxb1 $1 Kxb1 $1 3.h4 $1 a5 $1 4.h5 $1 a4 $1 5.h6 $1 a3
$1 6.h7 $1 a2 $1 7.h8=Q
    ( 7.h8=B )
7...a1=Q+ $1 8.Qxa1+ $1 Kxa1 $1 *

```

# Answer
> 3 votes
In the Matplus.net forums, Arpad Rusz shared the longest such sequence in a 6-piece position. The length of it is 19 plies.

You can check the uniqueness for yourself by using the Sygyzy tablebases..

```
[FEN "3k4/8/8/p4pP1/3K3P/8/8/8 w - - 0 1"]

1. h5 Ke7 2. h6 Kf7 3. Ke5 Kg6 4. Ke6 f4 5. h7 Kxh7 6. Kf7 f3 7. g6+ Kh6 8. g7 f2 9. g8=Q f1=Q+ 10. Ke7

```

# Answer
> -1 votes
do you mean this position?

```
2Q5/8/8/8/3n4/8/1b6/k2K4 b - - 0 1

```

---
Tags: endgame, draw, tablebases, records
---


# Question
Title: ChessBase: how to efficiently use two reference database simultaneously
In ChessBase I use the Mega Database as my reference database when in a board. However, I recently downloaded a Correspondence database and would like to look up positions in it as well. Is there a way I can easily use both reference databases when in a board?

So far what I'm doing is keeping the Mega Database as my default Reference, and for the Correspondence Database I: right click on it --\> click opening reference --\> and another board pops up where I can look up things in it. However, this is a bit inconvenient since I must keep tabbing between the two boards and manually making the same moves on each of them.

# Answer
> 1 votes
> Is there a way I can easily use both reference databases when in a board?

The obvious way is to create a new database by merging MegaBase and your correspondence database and use this new database as your reference database.

---
Tags: software, database, chessbase, correspondence-chess
---


# Question
Title: What are the shortest possible games with a) 20 Bishops, b) 20 Knights, and c) 20 Rooks?
The fastest move sequence to reach 18 queens is known. Similarly, what are the shortest possible games with a) 20 Bishops, b) 20 Knights, and c) 20 Rooks?

# Answer
In a Computer Chess Club archives page I wondered across, user Eduard Nemeth posted four proof games. Two of them demonstrate the shortest sequences known to me for knights and bishops.

```
[Title "20 Knights: 100 Ply, Zoltan Blazsik, 1997, Non-Unique Proof Game In 50.0 Moves"]
[FEN ""]
[startply "100"]

1. h4 g5 2. h5 g4 3. h6 Bg7 4. Rh3 gxh3 5. hxg7 h5 6. b4 a5 7. b5 Ra6 8. bxa6 a4 9. a7 a3 10. Bb2 axb2 11. a4 h2 12. g4 e5 13. f4 d5 14. e4 Be6 15. f5 h4 16. fxe6 f5 17. g5 h3 18. c4 Qd6 19. c5 f4 20. cxd6 c5 21. Bc4 dxc4 22. d4 c3 23. d5 c4 24. Qd4 exd4 25. a5 bxa1=N 26. a8=N c2 27. a6 c1=N 28. a7 c3 29. gxh8=N b5 30. Nb6 b4 31. a8=N b3 32. Na3 b2 33. e5 b1=N 34. g6 Na2 35. g7 Nh6 36. g8=N c2 37. d7+ Kf8 38. d8=N c1=N 39. e7+ Kg7 40. d6 h1=N 41. d7 h2 42. Nb7 d3 43. d8=N d2+ 44. Kf1 f3 45. e8=N+ Kh7 46. e6 f2 47. Kg2 d1=N 48. Nec7 f1=N 49. e7 Nhf2 50. e8=N h1=N

```

---

```
[Title "20 Bishops: 100 Plies, Zoltan Blazsik, 1997, Non-Unique Proof Game In 50.0 Moves"]
[FEN ""]
[startply "100"]

1. a4 b5 2. a5 c5 3. Ra3 b4 4. d4 Qb6 5. axb6 a5 6. d5 Nc6 7. dxc6 bxa3 8. b4 a4 9. b5 c4 10. Nd2 c3 11. e4 f5 12. e5 Nf6 13. exf6 f4 14. g4 h5 15. g5 Rh6 16. gxh6 g5 17. h7 g4 18. h4 g3 19. Qg4 hxg4 20. h5 g2 21. h6 gxh1=B 22. Ne2 f3 23. h8=B fxe2 24. f4 g3 25. b7 g2 26. f5 e5 27. bxa8=B cxd2+ 28. Kf2 a2 29. c4 a1=B 30. b6 d5 31. b7 d4 32. c7 g1=B+ 33. Kg3 a3 34. c5 a2 35. b8=B Ba6 36. c8=B Bb2 37. c6 a1=B 38. Bcb7 d1=B 39. c7 Bb3 40. c8=B d3 41. f7+ Kd8 42. f6 Bb4 43. f8=B d2 44. Bc5 e1=B+ 45. Bf2 d1=B 46. f7 e4 47. h7 e3 48. Bg7 e2 49. h8=B Bed2 50. f8=B e1=B

```

Addendum 2/25/2022: The shortest known rooks sequence, found by my hand, is now 102 plies.

```
[Title "20 Rooks: 102 Plies"]
[FEN ""]
[startply "102"]

1. b4 d5 2. g4 e5 3. h4 f5 4. a4 c5 5. c4 d4 6. f4 e4 7. Nf3 exf3 8. Nc3 dxc3 9. d4 a5 10. e4 h5 11. b5 Na6 12. g5 Nh6 13. bxa6 b5 14. gxh6 g5 15. d5 b4 16. e5 g4 17. Bd3 Bd7 18. Be4 Bb5 19. Qd4 Qg5 20. axb5 fxe4 21. hxg5 cxd4 22. g6 b3 23. g7 b2 24. g8=R b1=R 25. Rg5 Rb4 26. Bb2 a4 27. b6 a3 28. c5 Bg7 29. hxg7 axb2 30. c6 h4 31. c7 h3 32. d6 g3 33. Rh2 g2 34. Kf2 Kd7 35. Kg3 Kc6 36. f5 Ra7 37. c8=R+ Rc7 38. a7 g1=R+ 39. Rg2 c2 40. b7 d3 41. d7 e3 42. e6 d2 43. e7 e2 44. f6 f2 45. f7 h2 46. a8=R h1=R 47. g8=R f1=R 48. b8=R e1=R 49. f8=R b1=R 50. e8=R c1=R 51. d8=R d1=R

```
> 0 votes

---
Tags: problems, knights, bishops, rooks
---


title: Long algebraic notation-piece promotion

text:
# Question
Title: Long algebraic notation-piece promotion
I am building a chess engine with the use of Artificial Intelligence, and I am almost done as long as the AI and the internal game mechanics are concerned.

Currently I am training the AI and I want to get it to play with as many other AIs as possible. As I was searching, I came across the Arena interface which makes possible exactly what I want.

So I began to modify my engine to meet the specifications required for this to work and here is where my question lies. To be more specific, Arena uses the UCI protocol to make two engines communicate.

In the UCI protocol, the move format is in long algebraic notation. I would like to know how exactly long algebraic notation differs from algebraic notation, and more specifically how pawn promotion is represented.

# Answer
> 5 votes
Most games published for human study are written in short algebraic notation. For each move, the destination square is always specified, the moving piece is specified unless it's a pawn (in which case the origin file is specified for captures only), and if there's any ambiguity the origin rank and/or file is given to resolve it. Captures are indicated by inserting 'x' before the destination square. Promotion is indicated using eg. "=Q" suffix. Additional suffixes are used to indicate check, mate, and move quality.

Long algebraic notation is just like the above, except that the origin square is always exactly specified, and usually a '-' is inserted in place of the 'x' for non-captures. So Re1 might become Ra1-e1. The same suffixes are used, and castling is still specified using O-O type notation.

English descriptive notation is somewhat more arcane, and may specify only the piece identities if the resulting move is unambiguous, eg. RxB. It is now considered obsolete, though you might find it in old literature. I don't think it is used in any engine protocols. The same goes for foreign-language piece name abbreviations, eg. German chess uses *Springer* (S) instead of *Knight* (N).

The UCI protocol uses none of the above notations, but merely specifies the origin and destination squares; the only suffix is a *single letter* to disambiguate pawn promotions. So exd8=N in short algebraic would become e7xd8=N in long algebraic, but e7d8n in UCI (all in lowercase). Castling is specified by moving the king two spaces (in standard chess) or onto the corresponding rook (in 960) instead of in shorthand notation.

# Answer
> 3 votes
The following open source program: pgn-extract can do a lot of manipulations with PGN files among others convert them to long algebraic notation. I expect that you are familiar with the short algebraic form so if you want to learn the difference between these two form of notations you could convert some of your short games to long and look at the cases you are in doubt about. An alternative since it is an open source program is that you use the code from that in your code to convert from short to long and vice versa.

---
Tags: engines, notation
---


# Question
Title: Can an Irwin Cheat Detector catch a user who is using a Leela chess bot for cheating?
I’m a big fan of chess cheat detection apps, like Irwin that was created by lichess.org.

But I heard that there is a new bot called Leela that is teaching herself how to play chess, and to think in a human-like way. Is that true, and are there any ways to detect it?

# Answer
> 11 votes
Leela works by performing an exceptionally sophisticated positional evaluation at a relatively shallow search depth, whereas most chess engines work by performing a simple evaluation at as deep a search as possible. In theory this should produce a more positional style of play, and it does seem to be an effective strategy versus today's best conventional chess engines.

So in general, the moves selected by Leela will be different from those selected by Stockfish (Irwin's reference engine) in key positions. But the differences in move evaluation may be small from Stockfish's point of view; it's not that Stockfish thinks Leela's moves are *bad* per se, just that it doesn't reliably choose them for itself, because it doesn't see their unique advantages relative to a move that it has deeply researched tactically.

However, there are other characteristics of engine-users' play that differ from that of strong human players, and are observable and measured by Irwin.

Move timing statistics are an important one, and that probably won't change with Leela. Good human players recognise key moves, where many possibilities of nearly equal apparent strength exist, and plan ahead during them, taking more time. Then they play quickly when their opponent responds in the way they expected, or in easy positions where there is only one obvious good (or even legal) move. An engine user doesn't do this - for every move, they must enter the opponent's move into the engine, and wait a few seconds to see what to do.

Another characteristic which Irwin checks for is large variations in playing style, either between games or during a game. A player who plays some games extremely well with very few mistakes, but then plays other games (at the same time control) rather badly with several blunders, is probably a weak player who uses an engine for his good games. This is especially true if he seems to play his strong games against players with high ratings. Or a player might find himself losing a game, then get out the engine, in which case he will show blunders and a declining position, followed by extremely accurate play which salvages the game.

In short: yes, I believe Irwin can detect engine users, even if the engine in question happens to be Leela.

# Answer
> 2 votes
Unfortunately, if the cheater is smart enough, he's never going to be caught!

No matter how strong the cheat detector may be, if you only use the engine to help you out in one critical position, there is not enough data to get you caught.

Finally, the only thing that can be proven is similarity between your play and the engine's play, which does not constitute proof of cheating

---
Tags: engines, cheating, lichess, leela
---


# Question
Title: Looking for an iPhone app for working out chess problems
I'm looking for an iPhone app that will allow me to set up a chess problem and work out its solution. I've seen apps that present me with a battery of chess problems but don't allow me to set up my own. I've also seen apps that allow me to play chess starting from the opening position. But I haven't seen one that will allow me to configure the board as I choose. Admittedly I haven't tried every existing iPhone app but none of the ones I've looked at allow this.

# Answer
The only chess app on my iPhone is Stockfish, and it has a menu option Game -\> Edit position where you can set up your own board. You'd also have to change the Level/Game mode to 'Two player'.

It's a free app.
> 4 votes

# Answer
Mastersoft makes a Chess app, with similar modes to Glorfindel’s answer.

I do not remember if it was free.
> 1 votes

---
Tags: software, problems
---


# Question
Title: How to use the Ponder option in stockfish / UCI
I'm trying to understand stockfish Ponder functionality. I'm very interested to let stockfish think when the opponent is thinking. From what I understand you can do it as follows

```
$> uci
$> ucinewgame
$> position startpos moves e2e4
$> go wtime 599999 btime 600000
   ... // after 2 seconds
   bestmove d8a5 ponder a2a4
$> go ponder wtime 599999 btime 598000
// wait for opponent --> a2a4 (ponderhit)
$> ponderhit
   bestmove a7a5 ponder b2b4

```

But there is also a Ponder option

```
$> setoption name Ponder value on

```

No matter what I set it too

```
$> setoption name Ponder value 3

```

it doesn't complain and I'm not sure what it does. The behaviour is identical, I still have to manually do `go ponder...`. How should I use this option and what exactly does it do?

# Answer
The only purpose of the "Ponder" UCI option in Stockfish is to inform the engine about that you will use pondering so that it can consider this fact in its time management, as can be seen in https://github.com/official-stockfish/Stockfish/blob/46ce245763705c89dba60dcfda549dc1f64eb48b/src/timeman.cpp#L131-L132:

```
  if (Options["Ponder"])
      optimumTime += optimumTime / 4;

```

Since the option is boolean, you should enable it by setting it to "true", i.e.:

```
setoption name Ponder value true

```

Stockfish will then use a more aggressive time management, since it knows that it will also be able to use the opponent's thinking time.

This is consistent with how the UCI protocol defines the ponder option:

```
        *  = Ponder, type check
            this means that the engine is able to ponder.
            The GUI will send this whenever pondering is possible or not.
            Note: The engine should not start pondering on its own if this is enabled, this option is only
            needed because the engine might change its time management algorithm when pondering is allowed.

```
> 4 votes

---
Tags: stockfish, uci
---


# Question
Title: Two questions about how the en passant capture works
I am still confused about the en passant rule. There are two possibilities regarding the capture itself that are not clear to me.

```
[FEN ""]
1. d4 d6 2. d5 c5 3. dxc6 b5 (3. c4 e5 4. dxc6)

```

Scenario 1: In **main line shown above,** is it possible to capture via en passant again after 3... b5 with the move 4. cxb7ep? In other words, is it possible to capture en passant twice with the same pawn?

Scenario 2: As shown in the **given side variation**, is it actually possible to capture the black’s pawn on a later move? Note that although the black pawn is still in the diagram, you must imagine that it isn’t.

# Answer
> 18 votes
En passant can only be played when the enemy pawn moves *over* your pawn's capture square during it's first move (moving 2 squares); so the answer to both condition 1 and 2 is no.

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

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

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

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

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

# Answer
> 1 votes
A pawn capturing en passant (the d pawn in this case), basically interrupts the passage of the adjacent (c) pawn on his third rank (c6 for you), on the way from c7 to c5. This privilege can be exercised (retroactively) only on the **immediately** following move.

Once the c pawn has arrived at c5 (without interruption), there is no "second change" for the d pawn to capture him.

# Answer
> 1 votes
If, in the original diagram, above, Black's move had been 3. ... b6, White could not have captured it with the pawn on c6. Why would you think that because Black played b5, the c6 pawn could do so? It is simply *physically* impossible for a given pawn to capture en passant a second time.

# Answer
> 1 votes
While a pawn cannot capture en passant twice under the modern law of chess, it has not always been that way. We can play fast and loose with 19th-century rulebooks, as chess was not as standardized then. This is a thought experiment regarding the old rules of chess, all for fun.

As aforementioned, the rules weren't so cut and dry in the 19th century. Many joke problems were and have been made to exploit ambiguities in official rulebooks. The most famous is the loophole that allowed promotion into any of the opponent's pieces. However, the hypothetical legality promoting into an enemy pawn, on their first rank, was and is vague. Furthermore, there is the question of how it would move.

But we can take liberties with our imagination and assume it moves like normal, including being allowed a double-step on it's first rank. For example, Lichess's chess variant Horde Chess logicallly allows this movement. If you count the transformed pawns as the "same" unit after the wrong promotion, capturing en passant twice is possible.

This takes two stages. First, White plays en passant and then advances to the 7th rank

```
[FEN "4k3/6p1/8/7P/8/8/5P2/4K3 b - - 0 1"]
[startflipped ""]

1... g5 2. hxg6 null 3. g7

```

Now we pretend it promotes into an enemy pawn. Next, it advances forward to preform an en passant once more.

```
[FEN "4k1p1/8/8/8/8/8/5P2/4K3 b - - 0 1"]
[startflipped ""]

1... g7 2. null g6 3. null g5 4. null g4 5. f4 gxf3

```

Thus, the "same" pawn has captured en passant twice!

---
Tags: rules, en-passant
---


title: King or Queen-Which piece is which?

text:
# Question
Title: King or Queen-Which piece is which?
I recently bought a set of wooden chess pieces, which I liked for its simplicity.

I'm not sure, however, which one is supposed to be the king and which one is supposed to be the queen.

I would say that the one with the spike is the queen, and the one more flat is the king. Am I right, or is it the opposite?

# Answer
> 51 votes
In general, a chess set has the king as the tallest piece, followed by queen, bishop, knight, rook and pawn in that order. Notice in the starting position how the piece height decreases smoothly from the centre to the edge. (Also, when buying a chess set, usually the height of the king is given as a guide to the size of the chessmen.)

Thus I would say the king is the taller of the two pieces, which from your picture looks to be the one with the spike on the left.

This ordering of height may not hold for particularly ornate decorative sets.

However, if you're not going to use the set to play against other people in tournaments (where usually Staunton pieces are mandated anyway), the correct answer would probably be: the king is whichever piece you think it is.

# Answer
> 21 votes
At first glance, the taller piece with skinnier top would appear to be the King while the shorter, rounder piece would appear to be the Queen.

There are a few reasons why this would appear to be the case. The King often has a cross on top and the taller piece with the spike appears to more closely resemble that than the shorter piece, and in some sets the King looks like a larger bishop and the taller piece more closely resembles that, too. The Queen in some sets looks like a larger rook and the shorter, rounder piece more closely resembles a rook than the other piece.

Note: re prior commenter: the bundesform chess sets I have seen are even simpler in design than this and while some have tall bishops, the King is still taller than the Queen

# Answer
> 12 votes
## It doesn't matter.

As long as you and your opponent are in agreement about which one is the king and which one is the queen, it doesn't really matter what they were "supposed" to be.

That said, if they're easy to mistake, then you run the risk of someone making a misplay because they got confused about which one is which. Which would be unfortunate. If you and your opponent have different intuition about which one "looks" like the king, *one* of you will be disadvantaged by the arrangement you choose, no matter what you choose. So talk things over with your opponent before the match begins.

# Answer
> 9 votes
The piece on the right clearly reminds me of kings from German "Bundesform" piece sets, which are still occasionally used in Germany, although very rarely in tournament play. The left piece does not exactly look like a "Bundesform" queen, but it is still somehow similar.

# Answer
> 2 votes
It's very simple. The piece with the pointy top is the "King". As such, the other piece is the "Queen" by default.

# Answer
> -3 votes
The king is the one on the right, because that is the shape I know a chess king has, just that the cross is left out, still it has the shape of a King, therefore the right one is the king.

---
Tags: queens, kings, identify-this
---


# Question
Title: What is the most suitable position for a bishop here?
Recently I played a game with White whose link is: https://lichess.org/pAoAUp4O/white#42 and reached this position:

I am having a hard time finding why the moves I played next (22. Rxe8+? Rxe8 23. Bb2? ) are mistakes.

In particular, I am interested in knowing why on move 22, it is advisable to play Bb2 (something I find reasonable) and why on the next move, it is a mistake. Why the exchange of rooks makes such a move unsound? I brought the bishop to b2 because it occupies a nice diagonal and it defends my rook on a1 in case of an eventual check on h1 or g1 by the Black queen.

I can only come up with the fact that that with the Bishop on e3 (on move 23), I would be threatening the a7 pawn. However, I am not convinced that is the reason because such a threat can be easily dealt with by playing a6 or simply Bb6.

Besides, is the exchange of rooks (on move 22) wrong because there exists a stronger move or is it just a bad move in itself?

# Answer
> 20 votes
In the diagrammed position you have a material advantage but Black's position is a little bit better because his rooks are connected and he has a safer king position. His immediate threat is RxR, when you have to retake with the king followed by Qg1+ and after you move Kd2 he will play Bb6 and the pressure around your king will become intense. You are paying for your backward development with you queenside rook and bishop playing no part.

> Is the exchange of rooks (on move 22) wrong because there exists a stronger move or is it just a bad move in itself?

It is a bad move in itself because when you play RxR you immediately give control of the e file to your opponent. While you have a rook on e1 you are contesting the open e file.

If instead you play Bb2 you connect the rooks, complete your development and threaten Nxg7 which looks winning. It is a very hard threat to meet. You can meet Re6 with RxR and then carry out your threat. Probably Black has to play Be5. Then you swap bishops and play Ne7+ followed by Nxd5 and Black is just going downhill.

This course of action is much less effective if you start by exchanging rooks and ceding the e file to black. If you try the same tactic with your rook on a1 then black can comfortably play Be5 and retake with the queen after a pretty much forced BxB. With your material advantage you should still win but only after a grovelling defence as it is Black with the initiative making the threats. One of which is just to rush the h pawn down the board.

# Answer
> 14 votes
Brian Towers' answer is excellent. I'll just add this: **if you play Rxe8, you are effectively trading your e1-rook for your opponent's a8-rook**. A glance at the position should show that your e1-rook is a lot more valuable than your opponent's a8-rook. It is currently already developed and participating in the game, while the a8-rook (like your a1-rook) is doing nothing.

For the same reason, after 22. Bb2, Black should not play 22...Rxe1+.

---
Tags: analysis, bishops, rooks
---


# Question
Title: Looking for a comfortable DTC endgame database
The only online endgame database supporting DTC (Depth To Conversion) that I know of is jaet.

Unfortunately for me, the positions can only be entered by FEN. It is not possible to drag pieces, as I would prefer. Being able to drag the pieces around would be comfortable for me.

* Does anyone know a comfortable online endgame database supporting DTC, i.e. you can drag the pieces around?
* Does anyone know where I can download DTC-supporting files ? (I only have downloaded the Nalimov files, which only support DTM)

# Answer
After some extensive Googling, it appears to me that the the DTC tablebase named jaet that you linked is the only one that is online currently. As such, there may not exist "click and drag" DTC tablebases out there.

However, if you are still adamant about using a "drag" feature, you're best bet is to use the Lichess board editor to create your position, and then copy paste the FEN into jaet.

I'll demonstrate this easy process using some pictures for the benefit of any who do not understand how to do the above mentioned process. Some people are visual learners, so you never know.

1. Go the Lichess board editor.
2. Use the "drag" feature to create your position.
3. Copy the FEN.
4. Paste the FEN into the right bar at the jaet site
5. Click the "Lookup FEN" button that's next to the FEN bar and check the results.
> 1 votes

---
Tags: endgame, tablebases
---


title: How to use opening books on mac/linux

text:
# Question
Title: How to use opening books on mac/linux
I would like to use opening books for my stockfish chess engine, but I'm not sure how to do this. As far as I understand stockfish doesn't support these, so I though I setup a system next to stockfish, which is used until it doesn't return any moves anymore.

These .bin files can be found anywhere, for example

```
http://rebel13.nl/download/books.html

```

or

```
https://github.com/joeyrobert/ceruleanjs_opening_books

```

Anyway, I downloaded a couple of .bin files, and thought to use it with `polyglot-chess`

```
var Polyglot = require('polyglot-chess');

var obj = new Polyglot();

var fen = "rnbqkbnr/pppppppp/8/8/8/8/PPPPPPPP/RNBQKBNR w KQkq - 0 1";
console.log("Polyglot hash for fen " + fen + " is: " + obj.hash(fen));
console.log("Best move in the book is: " + obj.find(fen, "book.bin", true));
console.log("Random move in the book is: " + obj.find(fen, "book.bin", false));

```

Now when I try to run it

```
$> node index.js
internal/modules/cjs/loader.js:615
   throw err;
   ^

Error: Cannot find module '../build/Release/polyglot'
    at Function.Module._resolveFilename (internal/modules/cjs/loader.js:613:15)
...

```

I checked the build folder from polyglot-chess, but there isn't a polyglot file at that location.

# Answer
> 3 votes
You can do this on your own in a customized fashion (i.e. you control when to run the engine or to use the book) with a bit of scripting in python, using the python-chess module and a polyglot opening book of your choice. In this example I'm using `gm2001.bin`, which you can get from here.

As dummy example I have chosen two positions:

* `fen = 'rnbqkb1r/ppp1pppp/5n2/3p4/3P4/5NP1/PPP1PP1P/RNBQKB1R b KQkq - 0 3'` A basic Catalan position for which I know the book still has a move.
* `fen2 = 'rnbqkb1r/ppp1ppp1/5n2/3p3p/3P4/5NP1/PPP1PP1P/RNBQKB1R w KQkq - 0 4'` A position for which there are no book moves left in the chosen opening book.

What the code does is very basic: if it finds an opening move, then it makes that move (if there are more opening branches, you need to figure out how you want to choose the line to play), otherwise, it calls Stockfish with 10 seconds of movetime and makes the top engine move.

```
import chess
import chess.uci
import chess.polyglot

fen = 'rnbqkb1r/ppp1pppp/5n2/3p4/3P4/5NP1/PPP1PP1P/RNBQKB1R b KQkq - 0 3'
fen2 = 'rnbqkb1r/ppp1ppp1/5n2/3p3p/3P4/5NP1/PPP1PP1P/RNBQKB1R w KQkq - 0 4'
board = chess.Board(fen)
print board

handler = chess.uci.InfoHandler()
engine = chess.uci.popen_engine('stockfish_8_x64') #Provide correct address to where your engine is stored
evaltime = 10000

reader = chess.polyglot.open_reader('gm2001.bin') #Provide correct address to where your bin file is stored
n = sum(1 for _ in reader.find_all(board))

if n==0:
    print 'empty, using SF top move with 10 sec movetime'
    engine.info_handlers.append(handler)
    if board.is_checkmate():
        print 'Game has ended: checkmate'
    else:
        engine.position(board)
        eval = engine.go(movetime=evaltime)
        nextmove = board.san(eval[0])
        if handler.info["score"][1].cp != None:
            print 'Top move: ', nextmove, ' Evaluation: ',round(handler.info["score"][1].cp/100.0,2)
        else:
            print nextmove
        print board.variation_san(handler.info["pv"][1])
        print 'nodes: ', handler.info["nodes"], ' depth: ', handler.info["depth"], ' time: ', handler.info["time"]
        board.push_san(nextmove)
        print '---- Updated position:'
        print board
else:
    for entry in reader.find_all(board):
        print 'Found book moves:'
        nextmove = board.san(entry.move())
        print str(nextmove)
        board.push_san(nextmove)
        print '---- Updated position:'
        print board
        break

```

Output for the first `fen`:

```
r n b q k b . r
p p p . p p p p
. . . . . n . .
. . . p . . . .
. . . P . . . .
. . . . . N P .
P P P . P P . P
R N B Q K B . R
Found book moves:
c6
---- Updated position:
r n b q k b . r
p p . . p p p p
. . p . . n . .
. . . p . . . .
. . . P . . . .
. . . . . N P .
P P P . P P . P
R N B Q K B . R

```

and output for the 2nd fen (`fen2`):

```
r n b q k b . r
p p p . p p p .
. . . . . n . .
. . . p . . . p
. . . P . . . .
. . . . . N P .
P P P . P P . P
R N B Q K B . R
empty, using SF top move with 10 sec movetime
Top move:  Bg2  Evaluation:  0.24
4. Bg2 c5 5. c4 cxd4 6. cxd5 Qxd5 7. Qxd4 Nc6 8. Qxd5 Nxd5 9. Bd2 Ndb4 10. Na3 Be6 11. Ng5 Bd5 12. Bxd5 Nxd5 13. e4 Ndb4 14. Nb5 Nd3+ 15. Ke2
nodes:  14946976  depth:  21  time:  10001
---- Updated position:
r n b q k b . r
p p p . p p p .
. . . . . n . .
. . . p . . . p
. . . P . . . .
. . . . . N P .
P P P . P P B P
R N B Q K . . R

```

You should be able to take it from here and extend the code however you want.

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


# Question
Title: How does the chess24 rating compare to other server ratings?
My question is how the chess24 blitz-rating compares to the rating of other servers, like ICC or the ChessBase server. And whether the chess24-rating inflated over the last few month.

The reason for my question is that I used to play a little on chess24 and I had a rating of around 2100, which is comparable to my blitz rating on ICC or on ChessBase. But now after a hiatus of a few month I blitzed my rating quite steadily over 2300. Of course I want to know whether I'm just in stellar form (doesn't feel like it) or whether this is a peculiarity of chess24.

Edit: Maybe it was just stellar form. My new year tournament went very well indeed ...

Edit: Now it's four years later and I am usually rated around 2600 on chess24 with peaks up to 2800. Seems like there is a steady inflation going on.

# Answer
> 3 votes
From my own experience chess24 ratings are quite inflated. I can get a 2200 rating easy on chess24 but struggle to maintain a 1900+ rating on chess.com.

# Answer
> 3 votes
On chess24 I am much higher rated, around 2400+ (currently around 2440). On lichess I am around 2200. On chess.com the same. I am FM, and my FIDE is around 2200, for reference.

# Answer
> 2 votes
The Chess24 rating has undergone some changes over the last year, resulting on it being slightly inflated compared both ICC and Playchess ratings at the moment. This is a perception of my opponents' playing strength on my part (opinion) and my own ratings on the sites (N=1), so take it for what it's worth.

Chess 24 ratings started off at 1500, while the players who were drawn to it were relatively strong (for whatever reason), meaning people were relatively underrated in the beginning. They upped the rating at that point, and as far as I could tell and remember increased everyone's rating by 200 points on two occasions since launch.

# Answer
> 2 votes
The site is quite weird - on the one hand it’s similar to Lichess in the sense that the ratings are several hundred points lower in level than that of Chess.com; so a 2k player on Chess.com would be roughly 2200+ on Chess24. But on the other hand there are also tons of underrated players who are like 1700 but play to the level of a strong titled player as well an abundance of cheaters or auto bots due to the site’s obvious lack of cheat detection.

# Answer
> 1 votes
Chess24 ratings are quite overstated compared to other server ratings. You would always have a +100-200 Elo higher compared to other websites.

# Answer
> 1 votes
On ICC, and as a clubplayer, I have a rating around 1900. But on Chess24 I have now reached 2200. Now, that’s inflation!

# Answer
> 0 votes
I found chess24 full of relatively serious players whereas playchess seemed more like hobbyists. Your style might have changed a bit where you score well against serious players.

---
Tags: rating
---


# Question
Title: Online resources for medieval Persian chess games or problems?
I am looking for any collection of chess games of al-Suli or anyone medieval scholar's composition of games. Any resources would be appreciated.

# Answer
Take a look at this page. I hope it helps..
> 5 votes

# Answer
While it's not yet in the public domain, H.J. Murray's *A History of Chess* can be found on Google Books, and contains a large number of constructed shatranj problems.
> 1 votes

# Answer
I have found quite a few websites I popped the phrase for "Shatranj chess problem" into a search. The rules are, as always, on Wikipedia. Bishops represent alfils, and queens for ferz, in the following diagrams.

On chessvariants.com, there is an excellent resource page entitled "Chess Problems Of 1001 Years Ago." Here is the longest problem. This can be played out as the alfils and ferz are still.

```
[Title "The Water Wheel, Al-Suli, 930, Mate In 36"]
[FEN "rQ2nbbR/P5p1/pkp1pn2/1Pr2B2/2Pq2Pp/PN1P4/1N3p2/1KB3R1 w K - 0 1"]

1. Na4!+ Kb7 2. Na5+ Kc8 3. Nb6+ Kd8 4. Nb7+ Ke7 5. Nc8+ Kf7 6. Nd8+ Kg6 7. Ne7+ Kg5 8. Nf7+ Kf4 9. Ng6+ Kf3 10. Ng5+ Ke2 11. Nf4+ Kd2 12. Nf3+ Kc3 13. Ne2+ Kb3 14. Nfxd4+ Ka4 15. Nc3+ Ka5 16. Nb3+ Kb6 17. Na4+ Kb7 18. Nbxc5+ Kc8 19. Nb6 Kd8 20. Nb7+ Ke7 21. Nc8+ Kf7 22. Nd8+ Kg6 23. Ne7+ Kg5 24. Nf7+ Kf4 25. Ng6+ Kf3 26. Ng5+  Ke2 27. Nf4+ Kd2 28. Nf3+ Kc3 29. Ne2+ Kb3 30. Nd2+ Ka4 30. Nc3+ Ka5 31. Nc3+ Ka5 32. Nb3+ Kb6 33. Na4+ Kb7 34. Na5+ Kc8 35. Nb6+ Kd8 36. Nxc6#

```

In addition, I remembered a particular problem on Tim Krabbe's site in Journal Entry #146. The source is "100 Classics of the Chessboard" by Dickins and Ebert.

```
[Title "MS. 791 Casanatense Library, Rome, 15th Century, Mate In 6"]
[FEN "4k3/4P3/4P3/4P3/4P3/4P3/4P2B/R1N1K3 w Q - 0 1"]

1. Nb3! Kxe7 2. Ra8 Kxe6 3. Ra7 Kxe5 4. Ra6 Kxe45. Ra5 Kxe3 6. Re5#

```

Lastly, the Wikipedia page for Shatranj gives this classic.

```
[Title "Dilaram Problem, c. 10th century, Mate In 5"]
[FEN "1r4k1/8/5PP1/8/K1n3NR/7B/1r6/7R w KQkq - 0 1"]

```

Solution: 1. Rh8+! Kxh8 2. Af5+ (the alfil leaps over the knight) Kg8 3. Rh8+ Kxh8 4. g7+ Kg8 5. Nh6#
> 0 votes

---
Tags: chess-variants, history, problems
---


# Question
Title: Maximum number of non-pawn pieces on the board
In a reachable game, what is the maximum sum of queens, rooks, bishops, knights, and kings on the board?

For queens only, see Maximum number of queens possible

# Answer
@Aschultz is correct that 26 pieces is the maximum number of non-pawn and non-king pieces on the board. Since they said that they have not seen such proof yet, here it is to be seen.

```
[Title "me, chess.stackexchange.com 6/18/2019, Non-Unique Proof Game In 40.5 Moves"]
[FEN ""]

1. d4 a5 2. b4 c5 3. h4 e5 4. f4 g5 5. dxc5 axb4 6. hxg5 exf4 7. g4 b5 8. a4 h5 9. c4 f5 10. c6 f3 11. c5 f4 12. g6 b3 13. g7 b2 14. Na3 Nh6 15. g5 b4 16. g6 b3 17. g8=B b1=B 18. Bh7 Ba2 19. g7 b2 20. g8=B b1=B 21. e4 d5 22. e5 d4 23. e6 d3 24. Kd2 Ke7 25. Kc3 Kf6 26. e7 d2 27. Qc2 d1=B 28. e8=B f2 29. c7 f3 30. c6 Bb7 31. Bg2 f1=B 32. c8=B Bfe2 33. Bcd7 f2 34. c7 f1=B 35. c8=B h4 36. a5 Ra6 37. Rh3 Rb6 38. Rg3 h3 39. a6 h2 40. a7 h1=B 41. a8=B

```
> 6 votes

# Answer
A start...

```
[FEN ""]
1.g4 h5 2.g5 Nh6 3.gxh6 g5 4.h7 g4 5.b4 Rg8 6.h8=B g3 7.b5 a5 8.f4 e5 9.f5 Na6 10.bxa6 Rb8 11.a7 b5 12.a8=B b4 13.f6 Be7 14.fxe7 f5 15.c4 Kf7    16.e8=N f4 17.c5 d5 18.e4 d4 19.Na3 b3 20.c6 Bd7 21.cxd7 Qc8 22.d8=B c5    23.Nb5 c4 24.Ba3 b2 25.Bc5 c3 26.Ba3 b1=B 27.Bb4 c2 28.Ba3 c1=B 29.Bb4 f3    30.Bd3 f2+ 31.Ke2 f1=B+ 32.Ke1 g2 33.Nh3 g1=B 34.Ba3 Qd7 35.Bb4 Qd5  36.Ba3 Kg6 37.exd5+ Kh6 38.d6 Rb7 39.d7 Rb8 40.Bb6 Rb7 41.d8=B e4 42.Qa4 e3  43.Qc4 Bg2  44.Qb3 Bc6 45.Kf1 Bf2 46.Bc4 Bg3 47.Kg1 e2 48.Bd3 e1=B

```
> 2 votes

# Answer
I haven't seen a proof that the maximum number of non-pawns is 26. It seems intuitive, but let's try and nail it down.

In the starting position, no pawns can be promoted without captures.

So the question is, what is the maximum amount of promotions one capture can create? Say a pawn goes from column x to column y.

1. the pawn doing the capture may now be passed
2. an opposing pawn on column x may now be passed
3. a friendly pawn on column y may now be passed

So each pawn capture means a maximum of 3 pawns that can promote.

But there is a special case! What if there are doubled pawns in 2/3? They are dealt with as follows: if a previous capture moved them there, then it created fewer than 3 passed pawns, because they were not passed before this move. In the case of 2, the capturing x-pawn blocked them. In the case of 3, the opposing y-pawn blocked them.

So each capture means at most 3 pawns can promote. 1 means 3 promotions, 2 means 6, 3 means 9, and 4 means 12. But that would leave no further pawns to promote.

Now, to find a maximal case, we can just follow the link in the game, or play your game out so we promote all pieces to bishops. I have to admit I didn't fully check your game, but the idea seems right.
> 2 votes

---
Tags: problems, records, pieces
---


# Question
Title: Is there an online database for the endgame KRPPKRP?
It was stated at this forum that the 7-men-endgames are still not available online.

What about the special endgame KRPPKRP (Rook and 2 pawns against Rook and 1 pawn) ?

It would be nice if the database covers also DTC or DTZ, ideally both.

# Answer
> 6 votes
All of the Syzygy tablebases are available here: https://syzygy-tables.info/

These cover all endgames up to 7-man, and provide WDL (win-draw-loss) and DTZ (distance to zeroing move) data. Syzygy also distinguishes between a theoretical win or loss that can actually be forced into a draw by the 50-move rule, and one that cannot.

Here's an example for KRPPvKRP.

# Answer
> 5 votes
There exists a 7-men-endgames tablebase available online, the "Lomonosov endgame tablebase". see : http://chessok.com/?page\_id=27966

Unfortunately, it is not free yet.

# Answer
> 4 votes
The 7-men databases from Lomonosov are available for free via their Android app.

I've analyzed the traffic between the app and server a while ago, and discovered that it's easy to 'fake' your own calls to the server, so you're not depending on having an Android device nearby anymore. IIRC it worked with FEN strings. I don't have the specifics anymore, and it's probably against the Terms of Service of the app.

---
Tags: endgame, database, tablebases, rook-endgame
---


title: Helpmate of arbitrary length

text:
# Question
Title: Helpmate of arbitrary length
One of the FIDE rules states that if someone's flag falls, and *there exists a legal sequence of moves such that the other player mates the first player*, then the position is a win for the second player. This got me thinking whether this rule can theoretically be hard to enforce for arbiters, i.e. whether it is possible that the arbiter cannot (easily) decide whether a game is winnable for one side or not:

> Do there exist "hard" chess puzzles where the objective is to find a sequence of moves of *any* length, with both sides helping, so that one side wins? So essentially helpmate puzzles, but without specifying the number of moves until mate? Or is it always rather straightforward to determine whether, from a given position, there is a sequence of moves leading to mate?

Perhaps one way to make the job for the arbiter difficult is to not keep track of previous moves, and then present a position to the arbiter (when the flag falls) where it is difficult to prove whether one side can legally castle or not, or take en passant or not etc. - if such positions can only be won when say en passant is available, the arbiter (or the second player claiming a win on time, rather than a draw) would have to construct a proof game to show that the game can indeed be won.

In any case: I cannot come up with examples which are hard helpmates of any length, but I am in no way an expert when it comes to helpmates. Any thoughts or comments are appreciated!

**Edit**: This question is not about what is sufficient mating material, but about whether positions exist for which it is hard to decide if a mating sequence exists. This is more in the territory of artificially constructed helpmates/proof game problems than about simple, realistic adjournment situations for arbiters.

# Answer
> 9 votes
I don't remember where I first saw this kind of trick:

```
[Title "Could White (or Black) possibly win this?"]
[FEN "8/1p4p1/1Pp3p1/k1P3p1/1pP3Pb/1P4p1/6P1/7K w - - 0 0"]

```

Yes, the Kingside is necessary!

```
[Title "White mates in 19 (with Black's help)"]
[FEN "8/1p4p1/1Pp3p1/k1P3p1/1pP3Pb/1P4p1/6P1/7K w - - 0 0"]

1.Kg1 Ka6 2.Kf1 Ka5 3.Ke2 Ka6 4.Ke3 Ka5 5.Ke4 Ka6 6.Ke5 Ka5 7.Ke6 Ka6 8.Kf7! Ka5 9.Kxg6! Ka6 10.Kf7 Ka5 11.Ke7 Ka6 12.Kd7 Ka5 13.Kc7 Ka6 14.Kc8 Ka5 15.Kxb7 g6! 16.Ka8 Ka6 17.b7 Ka5 18.b8=Q Ka6 19.Qa7#

```

Black could mate a few moves later after (say) 19.Qf4 Ka5 20.Qf2 gxf2 etc.

P.S. It turns out the I first noticed this trick in a help-stalemate problem by Tivadar Kardos (see my comment below). Looking at that problem and some of his others suggests this improved setting of the same idea:

```
[Title "White's turn.  Could either side possibly win this? (NDE after T.Kardos)"]
[FEN "5brk/4p1p1/3pP1P1/1B1P2p1/3p2p1/3P4/4K1P1/8 w - - 0 0"]

```

# Answer
> 6 votes
Here's a famous helpmate problem where at first it is not clear that White can win at all:

```
[Title "Helpmate in 10 (Gabor Cseh, StrateGems 2001)"]
[FEN "8/5NR1/6PB/1P2P1P1/4P3/2p2p1p/pprp1p1p/kbqrbK2 w - - 0 0"]

```

Can White win this on time if Black (on the move) couldn't find a Queen or Rook before their flag fell?

(solution at https://www.chess.com/forum/view/more-puzzles/best-help-mate-puzzles)

# Answer
> 5 votes
Positions where a player would have adequate mating material but unable to achieve a helpmate are very rare. In almost call such cases, both sides will have a very limited number of possible moves until either the game was over (due to stalemate, checkmate, or draw by repetition) or the position opened up enough that a helpmate could easily be achieved.

While one could have a position where both sides have a substantial number of moves and yet no mate would be possible, e.g.

```
[FEN "k1bB/8/2p1p1p1/1pPpPpP1/1P1P1P2/8/8/K1Bb w - - 0 1"]

```

\[each side has promoted at least one pawn for a bishop\]

One may have to study the board for a little while to determine whether there is any means of either breaking the pawn barrier or producing a checkmate with pieces that are stuck on one side of it, but I wouldn't expect that any deep analysis should be required. Simply figure the range of squares that each piece could occupy without breaking the pawn barrier, and see if any piece could break the pawn barrier or if pieces could be arranged to create a checkmate. In the situation above, checkmate can be seen to be impossible because none of White's pieces except the king can ever control any light squares, the two kings can't get close, there's no dark square the Black king could occupy which doesn't have at least two light escape squares, and there's only one Black piece that could block a light escape square. Similar issues would prevent Black from mating White.

There may be some situations which would require a little care to determine whether a mate was possible, but analysis should be straightforward.

BTW, it's possible to achieve a position where White could have all his starting pieces, and be able to play hundreds of moves without a stalemate or threefold repetition, and yet be unable to achieve a helpmate.

```
[FEN "nb2kBBN/2p1PRRN/1pP2PPQ/1P4PP/8/8/4P3/6K1 w - - 0 1"]

```

Black can move his bishop back and forth and there's no danger of his becoming unable to do so, White can move his king all around the lower part of the board, and White may also push his e pawn four times. White's king can never get in a position to capture anything, the pawn can neither capture nor give check, and no other pieces can do anything at all.

On the other hand, there is one scenario where things might be complicated for an arbiter: if a position arises where the game will be drawn if it reaches a certain number of moves, the question of whether a helpmate can be executed before the game is drawn could be tricky to resolve since it would basically turn into a normal "helpmate in N" problem.

As a further observation, it is possible, at least in contrived situations, for one side to have a helpmate available only if castling is possible.

```
[FEN "6Bk/5P1P/7P/8/8/1p1p1p2/pp1P1P2/brn1K2R w - - 0 1"]

```

White can only helpmate black by castling. If White does anything else, Black's next move must be `...Ne2++`. After `O-O Ne2+`, however, White can move `Kh2`, escaping the check, and helpmate will become trivial.

# Answer
> 5 votes
Here's an old problem built round the idea of finding a tricky helpmate:

```
[TITLE "White to move. Last move? (A.Buchanan, StrateGems 2002)"]
[FEN "Bb1k1b2/bKp1p1p1/1pP1P1P1/1P6/p5P1/P7/8/8 w - - 0 1"]

```

Hint: by FIDE Law A1.3, if a future mate is not possible, even cooperatively, the game is over, drawn "in dead position". If the diagram position here is dead then the game is ended. But the prior position before the last move must have been alive though or the game would have ended then.

A1.3 applies "symmetrically", asking whether **either** player could deliver mate as a helpmate, and all the compositions so far in this thread focus on that. However off-hand I don't know of any composition which relies on the asymmetric rule (FIDE Law 6.9) associated with flag fall, where we only ask about **one** player's ability to helpmate. So there's a creative opportunity here... :D

Hint: bK is mated on:

> e8

# Answer
> 5 votes
If you are looking for helpmate problems of arbitrary length, then I have a few for you.

The longest legal helpmate with a **unique solution** is **28 moves long**, and this **record** has stood for **76 years and counting**! My source for it is the Die Schwalbe Chess Problem Database.

```
[Title "A. Hegermann, Fairy Chess Review 1934, Helpmate In 28"]
[FEN "6kR/4p1p1/1p2P1P1/1P2p3/1P2P3/1P2p1p1/4P1P1/5BK1 b - - 0 1"]

1... Kxh8 2. Kh1 Kg8 3. Kg1 Kf8 4. Kh1 Ke8 5. Kg1 Kd8 6. Kh1 Kc7 7. Kg1 Kd6 8. Kh1 Kxe6 9. Kg1 Kf6 10. Kh1 Kg5 11. Kg1 Kf4 12. Kh1 Kxe4 13. Kg1 Kd4 14. Kh1 Kc3 15. Kg1 Kxb3 16. Kh1 Kxb4 17. Kg1 Kxb5 18. Kh1 Kc4 19. Kg1 b5 20. Kh1 b4 21. Kg1 b3 22. Kh1 b2 23. Kg1 b1=Q 24. Kh1 Qf5 25. Kg1 Qf7 26. gxf7 Kc3 27. f8=Q Kd2 28. Qc8 Ke1 29. Qc1#

```

The longest legal helpmate **without a unique solution** is **48 moves long**. Once again, the source is the Die Schwalbe Chess Problem Database.

```
[Title "Karl Fabel, Schachmatt  1948, Helpmate In 48"]
[FEN "8/8/5p2/2p1pPp1/2PbPk1b/2pBp1pB/2P1P1P1/5BRK b - - 0 1"]

1... g4 2. Bxg4 Kg5 3. Bf3 Kh6 4. Bg4 Kg7 5. Bf3 Kf7 6. Bg4 Ke7 7. Bf3 Kd7 8. Bg4 Kc7 9. Bf3 Kb6 10. Bg4 Ka5 11. Bf3 Ka4 12. Bg4 Ka3 13. Bf3 Kb2 14. Bg4 Kc1 15. Bf3 Kd1 16. Bg4 Bg5 17. Bf3 Bh6 18. Bg4 Bf8 19. Bf3 Bd6 20. Bg4 Bc7 21. Bf3 Ba5 22. Bg4 Bb4 23. Bf3 Ba3 24. Bg4 Bc1 25. Bf3 Bd2 26. Bg4 Be1 27. Bf3 Bf2 28. Bg4 Bxg1 29. Kxg1 Ke1 30. Kh1 Kxf1 31. Bf3 Ke1 32. Kg1 Kd1 33. Kf1 Kc1 34. Ke1 Kb2 35. Kd1 Ka3 36. Kc1 Ka4 37. Kb1 Ka5 38. Ka2 Kb6 39. Ka3 Kc6 40. Ka4 Kd6 41. Kb5 Ke7 42. Kc6 Kf7 43. Kd6 Kg7 44. Ke6 Kh8 45. Kxf6 Kg8 46. Kg6 Kh8 47. f6 Kg8 48. f7+ Kh8 49. f8=Q#

```

Lastly, the longest helpmate in an **illegal position** is **111 moves** long! It is hard to imagine that there exists checkmating sequence in this position at all! The Die Schwalbe Chess Problem Database is still the source.

```
[Title "James Malcom & Arno Tüngler, Matplus.net Forum 1/30/2020, Helpmate In 111"]
[FEN "5b1b/2p1p1b1/1bPbPbpp/b1pPp1b1/1bPpPpkp/b1pBpPpP/1bPbPbPb/bBbBb1bK b - - 0 1"]

1... Kh5 2. Ba2 Ba7 3. Bb1 B5b6 4. Ba2 B4a5 5. Bb1 B3b4 6. Ba2 B2a3 7. Bb1 Bb8 8. Ba2 B6a7 9. Bb1 B5b6 10. Ba2 B4a5 11. Bb1 B3b4 12. Ba2 Bca3 13. Bb1 Bdc1 14. Ba2 Bcb2 15. Bb1 Bd2 16. Ba2 Bdc1 17. Bb1 Be1 18. Ba2 Bed2 19. Bb1 Bf2 20. Ba2 Bfe1 21. Bb1 Bg1 22. Kxg1 Bf2+ 23. Kf1 Bde1 24. Ba2 Bg1 25. Kxe1 Bd2+ 26. Kf1 Bbc1 27. Bb1 Be1 28. Kxe1 Bd2+ 29. Kf1 Be1 30. Kxe1 Bc1 31. Kf1 Bd2 32. Ba2 Be1 33. Bb3 Ba3 34. Ba4 Bc1 35. Bb5 Bb4 36. Ba6 Bba3 37. Bc8 Ba5 38. Bd7 B5b4 39. Be8 Bb6 40. Bf7 B8a7 41. Kxe1 Bd2+ 42. Kf1 Be1 43. Bg8 Bc1 44. Bh7 Bcd2 45. Bxg6+ Kxg6 46. Kxg1 Kh7 47. Kh1 Kg8 48. Kg1 h5 49. Kh1 B7h6 50. Kg1 Bf8g7 51. Kh1 Kf8 52. Kg1 Ke8 53. Kh1 Kd8 54. Kg1 Kc8 55. Kh1 Kb8 56. Kg1 Ka8 57. Kh1 Bb8 58. Kg1 Ka7 59. Kh1 Ka6 60. Kg1 Ka5 61. Kh1 Ka4 62. Kg1 Ka3 63. Kh1 Kb2 64. Kg1 Kc1 65. Kh1 Kxd1 66. Kg1 Kc1 67. Kh1 Kb2 68. Kg1 Ka3 69. Kh1 Ka4 70. Kg1 Ka5 71. Kf1 Bc1 72. Kxe1 Ka6 73. Kd1 Ka7 74. Kxc1 Ka8 75. Kb1 B6a5 76. Ka2 Ba7 77. Kb3 Kb8 78. Ka4 Kc8 79. Kb5 Kd8 80. Ka6 Ke8 81. Kxa7 Kf8 82. Kb7 Kg8 83. Kc8 Bf8 84.  Kd7 Bh8g7 85. Ke8 Kh8 86. Kf7 Bb6 87. Kg6 Kg8 88. Kf5 Bh8 89. Kg6 Bf8g7 90. Kf5 Kf8 91. Kg6 Ke8 92. Kf5 Kd8 93. Kg6 Kc8 94. Kf5 Kb8 95. Kg6 Ka7 96. Kf7 Ka6 97. Ke8 Ka5 98. Kd7 Ka4 99. Kc8 Ka3 100. Kb7 Kb2 101. Ka6 Kc1 102. Kb5 Kd2 103. Ka4 Ke1 104. Kb3 Kf2 105. Ka2 Kxg2 106. Kb1 Kxh3 107. Kc1 g2 108. Kd1 g1=N 109. Ke1 Nxf3+ 110. Kf1 Kg4 111. Kg2 Bb2 112. exf3#

```

---

I'd also like to add to @supercat's idea of casting in a helpmate. Here is the same concept, but in a lighter form that I made.

```
[Title "me, chess.stackexchange.com 6/20/2019, Helpmate In 2.5"]
[FEN "k7/Pp6/1P6/8/8/3p1p2/3P1P1p/R3K1nr w - - 0 1"]

1. O-O-O Nh3 2. Re1 Ng1 3. Re8#

```

Just for fun, here is the longest problem, from the Die Schwalbe Chess Problem Database, in which White must castle on their first move.

```
[Title "Frank Richter, Feenschach 6/5/2014, Helpmate In 7"]
[FEN "4k3/8/4p3/4P3/p1p5/PpPpPp1p/1P1PbP1P/R3K3 b Q - 0 1"]

1... Bf1 2. O-O-O Bg2 3. Rg1 Bh1 4. Rg3 Kf7 5. Rxf3+ Kg6 6. Rg3+ Kf5 7. f4 Be4 8. Rg5#

```

Lastly, from Yet Another Chess Problem, here is a helpmate in which castling must be the last move. This version comes from a thread in the MatPlus.net forums.

```
[Title "Mirko Degenkolbe & Steven B. Dowd, Die Schwalbe 2010, Version, Helpmate In 8.5"]
[FEN "8/8/8/2p5/p1PNp3/P1Pp1n2/Pn1P1Ppp/RNB1Kbkr w Q - 0 1"]

1. Nxf3+ exf3 2. Bxb2 Be2 3. Bc1 Bd1 4. Bb2 Bb3 5. Bc1 Bxc4 6. Bb2 Bxa2 7. c4 Bxb1 8. Bd4 Ba2 9. O-O-O#

```

# Answer
> 3 votes
A simple but partial counterexample, showing that if the history of the past moves is unknown, it can theoretically be impossible to decide whether one side can win or not.

```
[FEN "8/k7/2p5/KpP5/pP6/P7/8/8 w - - 0 1"]

```

If either side loses on time in this position with white to move, the other side would legally win if there is a legal sequence of moves to mate the opponent. However, it seems that white is in a stalemate position, and thus it's a draw. Unless black's last move was b7-b5, in which case cxb6 (en passant) would lift the stalemate and easily allow either side to win with the opponent's assistance.

In this situation, the immediate history of the position resolves the issue though - the arbiter could ask either player what was the last move, and use this information to draw the right conclusion. So perhaps there exist better counterexamples where drawing conclusions is even harder...

# Answer
> 2 votes
One pawn is sufficient for helpmate.

A bishop plus a knight is sufficient for helpmate.

A king plus bishop can deliver helpmate if the other side has at least one piece which can limit the king's mobility without stopping the bishop check and without checking the other king, so knight or bishop of the other colour.

Similarly a king plus knight can deliver helpmate if the other side has a bishop or a knight.

A lone king cannot deliver mate.

Any major piece is sufficient for helpmate.

Castling is irrelevant for helpmate. En passant is only relevant in blocked positions and players are obliged by 11.11 to help the arbiter in such situations.

> In any case: I cannot come up with examples which are hard helpmates of any length, but I am in no way an expert when it comes to helpmates.

Helpmates of arbitrary length are always trivial because it is either just a case of the mating side queening a pawn and mating or it is just a matter of one side getting rid of the right material and moving into position to be mated. What is difficult is helpmate in a set number of moves.

> Perhaps one way to make the job for the arbiter difficult is to not keep track of previous moves

This is nonsense!

Article 8.1.1

> In the course of play each player is required to record his own moves and those of his opponent in the correct manner, move after move, as clearly and legibly as possible, in the algebraic notation (Appendix C), on the ‘scoresheet’ prescribed for the competition.

As an arbiter when I see somebody not recording the moves I first ask them to bring their scoresheet up to date with all the moves. If they refuse I impose a time penalty. Repeated refusal results in loss of the game.

Note also article 11.11 of the FIDE Laws of Chess:

> Both players must assist the arbiter in any situation requiring reconstruction of the game, including draw claims.

---
Tags: rules, checkmate, problems
---


title: Games that illustrate attacking themes

text:
# Question
Title: Games that illustrate attacking themes
I have recently made an agreement with a bunch of highly interested but still inexperienced players and I will become their trainer. My plan is to have 1-2 meetings per week with them to talk about some relevant strategical topics and prepare their "training plan" for the days we will not meet (by now, consisting mostly of tactics and analysis of their own games)

I could find some illustrative games for most of the strategical themes that I would like to have a look at with them, like open files, the 7th rank, minor piece comparison (good and bad bishop, active and passive knights...), as well as pawn structure. I've also chosen a list of must-know theoretical endgames for them to learn.

However, before starting with these "more subtle" strategical topics, I would to begin with a few lessons on material and attack. Material advantage and simplification are no problem, but I am struggling to find illustrative games showing different types of attack. Ideally, the games should be easy to understand from a tactical perspective (by that I mean that, despite of course there being tactical complications, the strategical ideas should still be clear behind the forced-move mess) Classical games are also preferred since modern ones often require a great understanding of a particular type of position to follow, and I would prefer to show a more global view of attacking in chess.

Could you please provide me some reference to attacking games you consider illustrative/enjoyable? Any help is appreciated, even it you only contribute with one game. I would like to cover the following topics:

* Attacking a king in the center. First game in Nimzowitsch's book is great here. Morphy also comes to the rescue. What other examples do you know?
* Converting development advantage into attack against the king.
* Piece power in opened-center positions.
* Maneuvering the pieces into the enemy's castled position (more closed-position focused)
* Bayonet attacks (opposite-side castling): Here I am pretty much served, as some opening books on the Sicilian and French made the job for me, but other examples are welcome.
* Bayonet-attacks (kings castled on the same side): The best examples I found come from the King's Indian Defence. What else can I look for?

(After finding a good collection of games, I intend to show them 1-2 games per theme, and give them the rest so that they can make the analysis themselves)

# Answer
When it comes to maneuvering pieces to an enemy's king in a position, the following famous game with a king walk comes to my mind. The position isn't quite closed, but it does illustrate an attacking theme of walking the king across the board to a castled king. It has been nicknamed "A Long Walk Off a Short Peer" by chessgames.com.

```
[Title "Nigel Short-Jan Timman, Interpolis 15th, Tiligribg Netherlands, 1991"]
[FEN ""]

1. e4 Nf6 2. e5 Nd5 3. d4 d6 4. Nf3 g6 5. Bc4 Nb6 6. Bb3 Bg7 7. Qe2 Nc6 8. O-O O-O 9. h3 a5 10. a4 dxe5 11. dxe5 Nd4 12. Nxd4 Qxd4 13. Re1 e6 14. Nd2 Nd5 15. Nf3 Qc5 16. Qe4 Qb4 17. Bc4 Nb6 18. b3 Nxc4 19. bxc4 Re8 20. Rd1 Qc5 21. Qh4 b6 22. Be3 Qc6 23. Bh6 Bh8 24. Rd8 Bb7 25. Rad1 Bg7 26. R8d7 Rf8 27. Bxg7 Kxg7 28. R1d4 Rae8 29. Qf6+ Kg8 30. h4 h5 31. Kh2 Rc8 32. Kg3 Rce8 33. Kf4 Bc8 34. Kg5

```
> 4 votes

---
Tags: attack, teaching
---


# Question
Title: Short and long term plans in a closed game in the Sicilian Defense
Today, I have played a game as Black.

I reached this position, with Black to play:

The position, as you can see, is closed. The truth is that I had difficulty finding a plan here, considering the pawn structure, what are potential short and long term plans?

My Thoughts: There are no open files yet and the weakest point in White structure, which is located at d3, is by no means weak.

I considered moving a knight to g4 with the idea of exchanging with the dark-coloured bishop. But such an exchange would only put a pawn on e3, which would help White challenge the control of the dark squares. Thus, I quicky discarded this plan as I should be aiming to control the dark squares.

However, I am not sure what is the right plan. I guess that my plan should be preventing a d4 break by Qhite.

Can someone help me figure out a strategy for this game?

Note: I know that the computer suggests c4, but I am interested in a long term plan too. This is because, after that, there are no more breaks for me to aim for.

# Answer
> 8 votes
Before we talk planning, you can see from the diagram arrows that the tactical line 12.Nxd3 followed by c4 is available. A trade of c&b pawns for Whites e&d pawns = the center is Blacks; not to mention the monster on b7 is unopposed.

On to abstract thinking:

> "I considered moving a knight to g4 with the idea of exchanging with the dark-coloured bishop but such exchange would only give a pawn on e3 which would challenge the control of the dark squares."

This line of thinking is extremely flawed!

Trading a knight for a bishop is rarely a bad idea. Doubling the opponents pawns is also rarely a bad idea. In this particular case it is a good idea! Remember, doubled pawns have difficulty with mobility, and are therefore inherently weak. What do you think controls more dark squares, the Bishop on e3 or a pawn on e3?

Now, in general when the center is fluid, you need to be thinking about the center. "He who controls the spice controls the universe." and he who controls the center drives the battle.

So apart from the tactics available your planning should be around finishing development with an eye to conquering the center.

This position is so dynamic and full of tactics that it requires more concrete calculation than a long-term plan.

**Edit due to comments -- more on fxe3 doubled pawns:** With resulting pawns on e3, e4, d3; yes the pawn on e3 controls f4 nicely, but look at the cluster -- it can't move!

The e4 pawn is attacked twice (so the d3 pawn is stuck) and it's advance is suicide. Therefore the e3 pawn isn't going anywhere either.

So now black can make long-term plans. Piling up behind the c-pawn to play c5-c4 can result in White getting double-isolated-pawns on the efile. Or setting up a battery of Bb6 and Qa7 hitting the weak e3 pawn... There are various ways for Black to attack due to Whites weakened structure. Now what can White do? Looks like just defend. His knights have no active squares and his remaining Bishop is thwarted. White is clearly worse here.

---
Tags: sicilian-defense, positional-play, planning, closed-position
---


# Question
Title: What is the quickest way to reach a mutual, symmetrical stalemate?
What is the fastest known game that ends that in a mutual stalemate position that is symmetrical?

# Answer
> 3 votes
The fastest known is in **37 plies.** I found this in Journal Entry #361 on Tim Krabbe's website, which in turn pulled it from the 2007 5th issue of the chess magazine "Best Problems."

```
[Title "Evgeny Ghik, Shakhmatyi i Matematika 1983, Non-Unique Proof Game In 18.5 Moves"]
[FEN ""]

1. e4 d5 2. e5 d4 3. c3 f6 4. Qf3 Kf7 5. Qxb7 Qd5 6. Kd1 Qxg2 7. Kc2 Qxf1 8. Qxc8 Qxg1 9. Qxb8 Rxb8 10. Rxg1 Rb3 11. Rg6 Ra3 12. Rh6 gxh6 13. bxa3 Kg7 14. Kb2 d3 15. e6 a5 16. h4 a4 17. h5 c5 18. f4 c4 19. f5

```

In case the PDF link goes cold, here are the relevant sections.

# Answer
> 2 votes
There was a previous stack exchange answer which has a very amusing position where neither side can make a legal move.

Take a look; it is very enjoyable!

Mutual Stalemate

# Answer
> 1 votes
To be straightforward, there is **no such thing as a mutual stalemate**. Saying

> neither side could move on their turn

is a bit confusing. If it's white's turn, then they can be stalemated. Black cannot be stalemated as well, because his opponent has not moved to put him in stalemate.

---
Tags: problems, stalemate, records
---


title: Leela chess zero weight files

text:
# Question
Title: Leela chess zero weight files
I'm using Leela chess zero for a couple of days and found a couple of weight files here. But what is the place to be for weight files? I can imagine that lc0's strength is determined by the weight file.

For example, as you can see here, the project has a couple of weight files, which one should I use?

# Answer
> 3 votes
The weights for main networks are here. The best weights depends on whether you are using a cpu or gpu. For cpu, the best weights file is probably LD2 which is a small net trained off of data for t40. For strong gpus or longer searches, one of the recent t40 networks will be very strong.

---
Tags: leela
---


# Question
Title: How should I play after, or refute, the Tennison Gambit?
I played a game as Black in which I fell victim to a gambit trap and soon resigned. Stockfish labled it as the "Tennison Gambit."

```
[FEN ""]

1. Nf3 d5 2. e4 dxe4 3. Ng5 Nf6 4. d3 exd3 5. Bxd3 h6 6. Nxf7 Kxf7 7. Bg6+ Kxg6 8. Qxd8 Nc6 9. Qxc7 Nd5 10. Qg3+ Kh7 11. O-O e5 12. Qd3+

```

How should I play on after I accept the gambit, and how can I refute the gambit?

# Answer
> 6 votes
There is a saying that "the best way to refute a gambit is to accept it", attributed to Steinitz. While sayings in chess often have exceptions, I think it does apply to this particular case. If you go by either the Stockfish evaluation (-0.8) or the results of games between highly rated players (67% win for black out of 12 games), the gambit is a mistake.

The purpose of a gambit is to trade material for piece activity and the initiative. If you accept the gambit, your plan is usually to brace for the onslaught; if you survive the attack while keeping your material advantage, you can get a winning endgame. That means you have to play solidly and be especially careful about wasting time.

In addition to 5...Nc6 as suggested by Chromatix, there are other moves which prevent this attack. For example, a simple 5...e6 also works. It helps block the diagonal leading to f7 and gives an additional flight square to your king. But more importantly, by not moving the h pawn you still keep control of the g6 square. Other moves that work are 5...Nd7 or 5...Bd7, blocking access to the queen, or 5...Qd7, advancing the queen to a protected square. None of these look particularly attractive to me but they do prevent the tactic and let you keep your material advantage.

With that said, this was a blitz game, and I think gambits work better in blitz because there is less time to think about the proper defense, and going for an endgame with an extra pawn can be tricky because you might run out of time first. So another practical way to "refute" a gambit may well be to decline it, if only because players who play gambits usually *want* you to accept it, and by not doing what they want they may get frustrated, and it is possible that they haven't prepared for the declined variants as well as for the accepted.

# Answer
> 14 votes
It looks like your position fell apart pretty early on, a symptom of poor opening theory. Your King and Queen were exposed to attack within the first few moves, and White ruthlessly exploited that opportunity.

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

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

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

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

---
Tags: opening, gambits, opening-traps, counterplay
---


# Question
Title: Is it possible to have a double self-smothered stalemate?
I came up with this rather amusing and bizarre stalemate where Black stalemates itself by self-smothering.

```
  [FEN "8/8/8/8/8/3p4/pp6/krb1K3 b - - 0 1"]

  1...d2+?? 2. Kd1

```

The peculiar feature of this stalemate is that Black is unable to move not because moving a piece would put its king into check, but moving a piece would require it to capture its own piece, which is disallowed. This is an example of a **single self-smothered stalemate**.

The question is, is it possible to have a **double self-smothered mate**, such that both sides do not have any moves at all because the moves would require capturing of the side's own pieces?

One possibility suggested by the user supercat is the following -

```
      [FEN "KN1b4/RPpPp3/P1P5/4P3/8/3p1p1p/3PpPpr/4B1nk w - - 0 1"]

      1. e6

```

And both sides are stalemated. However, this position cannot occur in practice, because you cannot have a Black bishop trapped on d8 with the c7 or e7 pawns still on their original squares.

# Answer
I think I found a double-self-smothered-stalemate that could occur via sequence of legal moves from the normal starting position.

```
 [FEN "5bnk/4ppbp/4P2p/5P1P/p1p5/P2p4/PBPP4/KNB5 w - - 0 1"]

  1. c3 f6

```

Each player has seven pawns and two dark-square bishops, so one pawn from each player must have been promoted. Once White's b pawn has captured to a3 and Black's g pawn has captured to h6, White's g pawn and Black's b pawn can promote without any other pawn having to leave its file. I haven't worked out the exact "game", but I see no reason to believe it wouldn't be relatively trivial, particularly if one isn't worried about achieving the position with a minimal number of moves.
> 13 votes

# Answer
Here's a simpler mutual smothered stalemate (9 men on a side, no promoted pieces):

```
[Title "Mutual smothered stalemate"]
[fen "5brk/4p1pb/4P1p1/6P1/1p6/1P1p4/BP1P4/KRB5 w - - 0 1"]

```
> 9 votes

# Answer
Reduce number of units from Noam's record of 18 to a new record of 15.
(8+7 units, no promoted units necessarily on the board, pawn captures all achievable):

```
[Title "Minimal mutual smothered stalemate"]
[fen "5brk/4p1pb/4P1p1/6P1/6PB/6PK/6PP/8 w - - 0 1"]

```

Is this the best possible?

It's interesting that this solution is asymmetric. If you wrap both kings with pawns on opposite flanks, it requires 16 units.

EDIT: Inspired by a comment, I want to show more deeply that the position is legal. And if fact prove that, despite appearances *at least one promotion took place in the history of the game*. Assume first that no promotions happened.

White c-h pawns could have reached their files with 8 captures, which is OK since Black has 7 units left.

What about the Black pawns? All but 1 Black unit were captured by White c-h pawns. BfP ("Black f pawn") captured to g6, as this pawn couldn't have come from h7. Most efficient if BhP captured to g file, to be captured in its turn.

White pawns made 1,2,2,3 captures on files d,e,f,g respectively. So Black b,c,d pawns would have to make a total of 5 captures to get far enough (to d & e files). Together with the 2 captures onto the g file, Black made at least 7 pawn captures. This is making the most efficient assumption that BaP was the one missing Black unit not captured by a WP.

Black made 7 pawn captures, and White has 8 units remaining, so at first it looks OK. But none of these captures were on files a or b, where WaP & WbP began. One of those two WPs must have also got hit by a BP, but how? The only capture possible is of BaP.

Therefore, we have proved our original assumption wrong: at least one promotion happened in the course of the game. That might have been White or Black. E.g. WbP promotes on b1, or e.g. BbP captures only once, and promotes on c1.

---

As per @Laska"s given permission in the comments, here is a 35-move (optimal?) proof game created by @Rewan Demontay, of their position. The intention of it is that it was made to prove their retrograde analysis of the game history of their position.

```
[FEN ""]

1. Nc3 h5 2. Ne4 h4 3. Ng3 hxg3 4. fxg3 Nc6 5. Kf2 a5 6. Kf3 a4 7. Kg4 Nh6+ 8. Kh3 Ne5 9. b3 Nf3 10. exf3 Rg8 11. Bd3 Ng4 12. fxg4 d5 13. Be4 dxe4 14. Qf3 e3 15. dxe3 Kd7 16. Qxb7 Ke6 17. Ne2 Kf6 18. Bb2+ Kg6 19. Bf6 Kh7 20. Bh4 Kh8 21. Nf4 Bf5 22. Rhf1 Bh7 23. Ng6+ fxg6 24. Rad1 c6 25. Rd5 cxd5 26. c4 axb3 27. cxd5 bxa2 28. Rf4 Qd6 29. Qb5 Qe6 30. dxe6 a1=Q 31. Qc5 Qa4 32. Qd5 Qxf4 33. exf4 Ra5 34. Qg5 Rxg5 35. fxg5

```

As you can see, a **promotion** is **needed** as @Laska **rightfully claimed.**

EDIT: Thanks @Rewan. And here is a candidate *maximal* mutually smothered checkmate:

```
[Title "Maximal mutual smothered stalemate"]
[fen "4brkq/3p1brb/3Pp1p1/4P1P1/1p1p4/1P1Pp3/BRB1P3/QKRB4 w - - 0 1"]

```

Legal position with 26 pieces: 6 minor pieces captured & 4 promoted bishops. Some flexibility in the diagram: in keeping with the maximality I've chosen major pieces rather than knights in the back row. Also, kept the smothered kings out of the corners.

Note the pawn moves d2-d3 and e7-e6 unlock the two cages.

Here is a proof game for the 26 unit position.

```
[FEN ""]

1. h4 a5 2. h5 a4 3. h6 a3 4. b3 g6 5. Bb2 Bg7 6. hxg7 axb2 7. a4 h5 8. a5 h4 9. Rh3 Ra6 10. c4 f5 11. Nc3 Nf6 12. Ne4 Nd5 13. cxd5 fxe4 14. Rc3 Rf6 15. f4 c6 16. a6 h3 17. a7 h2 18. a8=B h1=B 19. g8=B b1=B 20. d6 e3 21. Bc4 Bf5 22. Bd3 Be6 23. Qc2 Qa5 24. Qb2 Qe5 25. O-O-O Bg8 26. Bb1 Bh7 27. Ba2 O-O 28. Rc2 R6f7 29. Qa1 Qh8 30. Rb2 Rg7 31. Kb1 c5 32. Rc1 b5 33. g4 b4 34. g5 Bcb7 35. Bg2 Bd5 36. Be4 Bf7 37. Bc2 Be8 38. Bd1 Bd5 39. Nf3 Bdf7 40. Be4 Nc6 41. Bec2 Ne5 42. Nd4 cxd4 43. fxe5 e6 44. d3

```
> 9 votes

# Answer
In response to an your original question about whether anything interesting has been written about stalemates, it may be worth mentioning that puzzle creator Sam Lloyd is often credited with two interesting stalemate "games" (though see game 3679 at http://www.chesshistory.com/winter/winter08.html for information about that attribution); in the first, White stalemates Black on the tenth move, after having captured six black pieces:

```
[FEN ""]

1.e3 a5 2.Qh5 Ra6 3.Qxa5 h5 4.Qxc7 Rah6 5.h4 f6 6.Qxd7+ Kf7 7.Qxb7 Qd3 8.Qxb8 Qh7 9.Qxc8 Kg6 10.Qe6

```

In the second, White is stalemated after Black's twelfth move, while all 32 chessmen are on the board:

```
[FEN ""]

1.d4 d6 2.Qd2 e5 3.a4 e4 4.Qf4 f5 5.h3 Be7 6.Qh2 Be6 7.Ra3 c5 8.Rg3 Qa5+ 9.Nd2 Bh4 10.f3 Bb3 11.d5 e3 12.c4 f4

```

In both of Sam Lloyd's positions, one side is stalemated while the other has many moves available. For both sides to be stalemated would probably take significantly more moves, and for both sides to be smother-stalemated would take more yet.
> 4 votes

# Answer
Just for fun, here is an attempt at **optimizing** the number of pieces that can be involved. I was able to manage **24 pieces.**

```
[Title "me, chess.stackexchange.com 6/23/2019, mate in 20"]
[FEN "5brk/4p1pb/4p1p1/p3P1Pp/Pp1p3P/1P1P4/BP1P4/KRB5 w - - 0 1"]

```
> 1 votes

---
Tags: problems, stalemate
---


# Question
Title: I played my first (rapid) tournament recently and I wanted to calculate my ELO
According to FIDE regulations I should calculate the average of my opponents and just plug it here: https://ratings.fide.com/calculator\_rp.phtml. I scored 5/9 but a couple of players didn't have rapid rating so I don't know if I should count those players as 0 points of ELO or just calculate the avg without them. Also I don't understand the point 8.21 of the handbook:

> 8.2 Determining the Rating 'Ru' in a given event of a previously unrated player.
>
> 8.21 If an unrated player scores zero in his first event his score is disregarded.
> First determine the average rating of his competition 'Rc'.
>
> > (a) In a Swiss or Team tournament: this is simply the average rating of his opponents.
> >
> > (b) The results of both rated and unrated players in a round-robin tournament are taken into account. For unrated players, the average rating of the competition 'Rc' is also the tournament average 'Ra' determined as follows:
> > (i) Determine the average rating of the rated players 'Rar'.
> > (ii) Determine p for each of the rated players against all their opponents.
> > Then determine dp for each of these players.
> > Then determine the average of these dp = 'dpa'.
> > (iii) 'n' is the number of opponents.
> > Ra = Rar - dpa x n/(n+1)
>
> 8.22 If he scores 50%, then Ru = Ra
>
> 8.23 If he scores more than 50%, then Ru = Ra + 20 for each half point scored over 50%
>
> 8.24 If he scores less than 50% in a Swiss or team tournament: Ru = Ra + dp
>
> 8.25 If he scores less than 50% in a round-robin: Ru = Ra + dp x n/(n+1)

Should I calculate my 'Ru' using the average of the rating of my opponents, of the whole tournament or is it more complicated than that?

Thanks in advance.

Here are the games and opponents, I have only the 9 games I talked about so it might help: https://ratings.fide.com/chess\_statistics.phtml?event2=&event=1669320

# Answer
OK, so the tournament was the Rattenberger Schnellschach-Open 2019 Tiroler Einzelmeisterschaft im Schnellschach It was a Swiss tournament. Here are your results from the tournament.

One of your opponents, Karl-Heinz Staudacher, has no rating. You should exclude your result against him altogether.

One of your opponents, Manuel Keßler, has a standard rating but no rapid rating. In the listing his standard rating has been used for pairing purposes and I believe this will also be used in rating calculations.

That means that you scored 4/8 against rated opposition. Accordingly (8.21a and 8.22) your rating will just be the average of those 8 opponents' ratings = 1885.5 which will be rounded up for display as 1886. If you play more FIDE rated rapid tournaments in June then the results from these tournaments will also be used in your calculations.

> I don't understand the point 8.21 of the handbook

This first says that if you score 0 in your first tournament then all your results in that tournament are excluded from the calculations. This is usually a good thing because it means that results which would give you a low rating (or no rating at all if it works out at below 1000) are not used.

Coaches of weak players playing their first tournament and losing their first few games often advise the player to either lose the last game or two or to pull out of the tournament to take advantage of this rule.

The rest is just giving the rules for calculating rating in case of round robin and Swiss. Your tournament was Swiss so you should use those rules.
> 8 votes

# Answer
Based on the screenshot, I believe this was a Swiss tournament. In that case, you ignore the unrated opponents. Do not average in a rating of 0, and do not count the results against those players.

The `Ra` is the average rating of your rated opponents, not the average rating of the entire tournament, based on this line:

`In a Swiss or Team tournament: this is simply the average rating of his opponents.`
> 5 votes

---
Tags: tournament, rating, elo
---


# Question
Title: Collusion in a simultaneous blindfold exhibition
When a blindfold expert plays several players simultaneously, there is a tacit assumption that the players will not collude. But suppose that the players are allowed to collude, and their goal is to maximize the chances of making the expert lose track of or forget the exact configuration on at least one of the boards. (I'm assuming that they do this not by indulging in unsportsmanlike behavior unrelated to chess itself, but only by judicious move selection.) What strategy should they adopt?

I suspect that a good strategy would be to choose very similar but slightly different moves, like playing b6 and g6 and then shuffling the bishops back and forth in some random manner. If the expert is using memory palaces or some such technique then it will be challenging to come up with mnemonics that accurately distinguish between such similar positions.

Have any blindfold experts prepared for the possibility of such collusion? What strategies worry them most? How many simultaneous blindfold games would be possible if this kind of collusion were allowed?

# Answer
> 1 votes
**Partial Answer**

Just in case it gets deleted, @shivksy left a helpful comment that seems to partially answer the question. It would make a good answer in itself in my opinion.

Here is the comment in it's full glory:

"Fascinating topic. An answer may lie within the book amazon.com/Thought-Choice-Chess-Adriaan-Groot/dp/4871877582. One of the observations made in this very scientific treatise on chess thought process is that Grandmaster memory/recall for non-standard/weird positions that cannot be chunked and recalled is surprisingly no better than lower rated players. In other words, they are pattern-recognition geniuses who are a bit more helpless with statistically infrequent patterns. Perhaps one could stress our expert to store (without the power of chunking) a ton of weird positions?"

---
Tags: simultaneous, blindfold-chess
---


# Question
Title: The highest amount of moves by the losing side in a zugzwang
In zugzwang, the usual idea is to limit the number of moves that the opponent can make. But they can also have many moves in certain scenarios. What is the highest amount number of moves by the losing side in a zugzwang position, with and without promoted pieces allowed?

# Answer
> 7 votes
The following are full-point zugzwangs, so both sides are losing if either moved!

```
[Title "Noam Elkies. EG 128, Apr 1998, p.53, 10967 (v)"]
[StartFlipped "0"]
[fen "8/8/k7/8/K7/RNbn4/B7/1R6 w - - 0 1"]

1. Rc1 Nb2#

```

White: 8 with wRb1, 6 with N = 14. Black: 11 with B, 8 with N, 3 with K = 22. Total-36.

```
[Title "Noam Elkies. EG 128, Apr 1998, p.53, 10967 (text, v)"]
[StartFlipped "0"]
[fen "8/8/8/k1n5/8/K7/RRb5/QBb1n3 w - - 0 1"]

1. Bxc2 Nxc2#

```

White: 1 with B = 1. Black: 9 with Bc2, 6 with Bc1, 8 with Nc5, 3 with Ne1, 1 with K = 27. Total-28.

# Answer
> 4 votes
If you allow promoted pieces in the diagram: The following is a half-point zugzwang.

```
[Title "half-point zugzwang: WTM draws. BTM loses in 14"]
[StartFlipped "0"]
[fen "3q4/8/4q3/2Q5/k7/8/8/2K4Q b - - 0 1"]

1... Qg5+ 2. Qxg5! Qc4+ 3. Kd2

```

It is a draw if it is white to move. Meanwhile, if it is Black to move, they lose in 14 moves. Black has 25 moves with Qe6, 21 moves with Qd8, and 1 with Ka4, for a grand total of 47.

---
Tags: problems, records, zugzwang
---


title: The difference between Rad1 and Rfd1

text:
# Question
Title: The difference between Rad1 and Rfd1
I've always wondered, what are the main tactical and strategic differences between Rad1 and Rfd1 (or Rad8 and Rfd8 as black)? I know it's a subtlety, but my guess is there are some common principles that apply often.

# Answer
When you move one rook to the center, the other rook, obviously, cannot cross it. If you play Rfd1, you cannot then play Rae1. And if you play Rad1, you cannot then play Rfc1. So, part of this decision is planning ahead and thinking about which *other* file you are likely to want a rook on.

Relatedly, if you play a move like Rae1, you are trapping your f-rook, often making it vulnerable to an attack from the bishop. Be careful before playing a move like that.

If the opponent has a bishop on g7, it is sometimes a good idea to get the rook off of the a1 square, especially if the center is not closed. This allows you to more easily play b3 or b4 without putting your rook in danger from the bishop.
> 14 votes

# Answer
Normally, when I need to choose between one of my rooks, whether to move on a promising center column or to defend a center pawn, I wonder myself which side columns are better.

If there is not a task to do on queenside's columns, I move the a-rook. The f-file rook, which is the h-file rook after castling, is used to better protect the castled king, as well as to provide support to f4 if a7-g1 diagonal is not controlled by a black bishop.

Sometimes, moving the f-file rook is indeed not recommendable because f2 might need the f-file rook as a defender.

Cases where I move my f-file rook are mostly related with plans of playing Rab1 or Rac1, with no troubles for my castled king. Additionally, as @DM noted, if it is Rae1, the needed move, the f-file rook gets trapped.
> 3 votes

# Answer
It comes down to what squares you want your rooks to be on, which in turn is driven by strategical considerations for where your rooks are going to be most active. In general you want your rooks to be on open files (files in which there are no pawns of either color), or semi-open files (files with an enemy pawn but not one of your own) if open files are not available. Of course this is abstract, so let's take a concrete example.

```
[FEN ""]
  1. e4             c5
  2. Nf3            d6
  3. d4             cxd4
  4. Nxd4           Nf6
  5. Nc3

```

This is the starting point of a myriad possibilities in the open Sicilian. If we just proceed from here then it should be clear that Black wants a rook on the c-file while White wants a rook on the d-file. This is because those are their respective semi-open files. A rook on c8 for example would control four squares (c7, c6, c5, c4) and is also instrumental in the iconic Sicilian exchange sacrifice ...Rxc3. For the other Rook, Black wants it on the d-file to support the standard Sicilian equalizing break ...d5, while White would prefer the e-file since 1) the Rook controls most squares there and 2) the pawn push e5 is a standard attacking idea.

Therefore in the Sicilian, Black is probably not playing ...Rad8 because he is playing ...Rac8 and ...Rfd8, while White is probably playing Rad1 and Rfe1.

*However*, a lot of this is going to depend on the position. Let's take this position and add a few more moves:

```
[FEN ""]
  1. e4             c5
  2. Nf3            d6
  3. d4             cxd4
  4. Nxd4           Nf6
  5. Nc3            g6
  6. Be3            Bg7
  7. f3             O-O
  8. Qd2            Nc6
  9. Bc4            Bd7
  10. O-O-O

```

Now we are in a Sicilian Dragon, Yugoslav attack. This is a sharp line where both sides are looking to attack the other's king. Black still wants a Rook on c8, and maybe on d8 as well (although doubling on the c-file is also a real possibility), but White no longer wants his Rooks on d1 and e1. Instead, White wants his rooks on g1 and h1 to support pawn pushes against the Black king. Rooks on d1 and e1 is no longer effective because in this pawn structure, White's active plan is going to involve pawn advances on the kingside and rooks on these two squares don't contribute to that plan.

So: it comes down to where you want your rooks to be, which in turn comes down to the specifics of the position.
> 2 votes

---
Tags: strategy, tactics, planning
---


title: Chess movie as educational incentive

text:
# Question
Title: Chess movie as educational incentive
I am trying to encourage a young friend to learn chess. He is very interested, just like any child would be with a child's play. I am wondering which movie about chess to choose, that could cause more interest and improved learning to him.

# Answer
Searching for Bobby Fisher maybe. Trailer: https://www.youtube.com/watch?v=8khmNiamBxo

http://www.imdb.com/title/tt0108065/
> 5 votes

# Answer
In addition to great suggestion by Mark. You can also try Brooklyn Castle: http://www.imdb.com/title/tt1800266/

It seems quite inspirational, the main message 'it's also cool to play chess'.
> 1 votes

# Answer
First movie that came to my mind was Life of a King, but some scenes are not recommended to young children. You should watch it before and then decide yourself!

Maybe you can also check out Algorithms. I didn't manage to see it, but seems to be quite inspirational.
> 1 votes

# Answer
* Queen of Katwe
* Lang Leve de Koningin (i guess only available in dutch and german?)
> 1 votes

# Answer
A movie that I like about chess is "The Luzhin Defense".

However, the movie might encourage your friend not to be obsessive with chess. Anyhow, the tactical problems showed in the movie deserves a view if you are yet a chess player.
> 1 votes

---
Tags: teaching
---


title: Chess principles for beginner

text:
# Question
Title: Chess principles for beginner
I'm trying to put together a flyer of the golden rules in chess for kids that are absolute beginners. I noticed that they ran into the same trivial mistake that could be easy to fix with a simple switch, and I guess the flyer could help flipping it. Here is my list so far, kinda ranked by how important the principles are :

**Practical :**

1. I shall take my time on each move, at least a good 20 seconds
2. I shall pay attention to what’s my opponent last move and what is the intent
3. I shall make sure that neither I nor my opponent is giving away a piece
4. I shall keep my hand on my chin as long as I am not sure of what will be my next move
5. I shall never resign
6. A bad plan is better than no plan
7. I shall not reveal my intent orally to my opponent
8. I shall consider my opponent plays like a grandmaster
9. Do not focus on one sector of the board. View the whole board

**In game :**

1. In the opening, I shall deploy the knights, bishops, and then castle.
2. I shall not take out my queen in the opening
3. I shall use my king in the endgame
4. I shall connect my rook
5. I shall try to control the center
6. A knight on the rim is dim
7. Rooks smile on open files
8. When behind in material, I shall trade pawns. When ahead, trade pieces
9. I shall avoid doubled, isolated or backward pawns and try getting passed pawns instead
10. Whenever possible, I shall place my rook on the 7th or 8th rank
11. I shall double my rooks on the 7th rank

What do you guys think of it? Any other important principles I didn't think of? Feel free to use it.

**Edit : Here's the final look of it. Feel free to use it !**

# Answer
> 1 votes
The idea of giving your students some guidelines for playing good chess is good in principle, but we have to be aware of its limitations too. For the "practical" ones:

* 1 This is great until you play a 5-minute blitz game. You also don't often need 20 seconds in a capture-recapture sequence. This illustrates the main problem with trying to create fixed rules, they don't apply in every situation. I would go for "think until you make sure you are not blundering"
* 2, 3 and 4 are good pieces of advice!
* 5 is just bad etiquette. I understand what you mean but you should definitely resign if you are a queen and two rooks down in material
* 6 is pretty controversial. Just say "I shall find a good plan". Anyway beginner games are rarely decided on planning but on blunder exploitation
* 7, 8 and 9 sound fine to me.

The "in-game" principles are generally OK, but meaningless outside of their context, sometimes even false or contradictory with one another. If you are going to present them, please do so by providing good examples of how those rules actually apply.

As a final thought, please keep in mind that it's better to let your student figure out the "in-game" principles themselves rather than you showing them as if they were the Ten Commandments. Your mission should be to give them hints in their discovery, rather than being the word of Truth. For the sake of example, let's take in-game rule No. 6. I would review one of their games where they have an awful knight, then try to help them figuring out why the enemy's attack was so devastating. Eventually, they'll see how useful the knight would have been in an active square creating counterplay

---
Tags: teaching
---


title: Enable pondering with Leela chess zero

text:
# Question
Title: Enable pondering with Leela chess zero
I just got Leela Chess Zero up and running inside docker using this guide. Added a couple of weights from here

Now, when I run leela

```
$> lczero -w path/to/weight/file
go
info depth 16 nodes 435 nps 48 tbhits 0 score cp -437 time 9085 pv b5c4 d3c4 d5b4 ...
bestmove b5c4

```

I've used stockfish before, which also returns a ponder move

```
bestmove b5c4 ponder d3c4

```

Here is described that you can use `--ponder` to enable it, but that option is not recognized. Is something like this also possible with Leela?

Furthermore, I've seen different weight files, where can I find good weight files?

# Answer
> 2 votes
After asking on the Discord as @Oscar Smith suggested in a comment, I got some results.

The person I asked said that you could download good weight files for Leela from this webpage: http://lczero.org/networks/

This was also said: "nT40.T8.610 (used in TCEC Sufi): https://www.dropbox.com/s/rmcf0lf1hes10gi/256x20.T8-swa-610000?dl=0 and currently in use in TCEC Rapid is 42547.pb.gz from above page. LCZero won Season 15 TCEC Superfinal with above net T40.T8.610, but might not any more be strongest one."

I'm assuming that it's relavant to what you need.

Here is the Leela Chess Zero Discord link so you can find out more: https://discordapp.com/invite/pKujYxD

---
Tags: engines, leela
---