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K+B+N vs. K endgame & 50-move rule

K+B+N vs. K endgame & 50-move rule

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Has it been shown that 50 moves are sufficient to win in a K+B+N vs. K engame, _from any starting position_ where the black K does not win the B or N? I looked a this the other day and I'm having some doubts.

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Apparently some positions do run into the 50 move rule even with perfect play but there aren't a huge number of them.
Of course my source isn't the greatest so I may be proved wrong.

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Yes, it has. I believe the longest win is 33 moves. You can download a 4-man endgame database/tablebase for your chess program to analyze such positions. If you want me to I could find a website where you could download endgame databases.

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Here's a website where you can download it: http://behind.chesslib.no/dl_showsub.asp?cat_id=14&cat=Nalimov To accelerate your download I reccomend using Free Download Manager (which can be found here: http://www.freedownloadmanager.org/). It makes multiple connections to the server so your download speed can be up to about 5 times faster. You still can't go faster than your bandwith limit though.

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Are you allowed to use tablebases in CC?

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Of course not!

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Originally posted by bobbob1056th
Of course not!
OK, just wondering. Since you're allowed to use opening databases, it'd stand to reason that you'd be allowed to use another similar 'common shared knowledge' thing. Guess not.

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Originally posted by CrawlIce
Has it been shown that 50 moves are sufficient to win in a K+B+N vs. K engame, _from any starting position_ where the black K does not win the B or N? I looked a this the other day and I'm having some doubts.
theory says it's a win. but you can go a lifetime and not encounter this b + n endgame, so maybe don't even bother to learn it.

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It has been proven to be a win (except where a piece will be lost). Computers have analyzed every single position that can occur on the board with KBNK.

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Originally posted by bobbob1056th
Of course not!
in reply to Ark13
Are you allowed to use tablebases in CC?
Endgame tables are allowed. The terms of service state that books and databases are allowed, and endgame tables are essentially a database.

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Are you serious!? I'm going to check the terms of service.

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Originally posted by CrawlIce
Has it been shown that 50 moves are sufficient to win in a K+B+N vs. K engame, _from any starting position_ where the black K does not win the B or N? I looked a this the other day and I'm having some doubts.
As has been stated, it takes less than 35 moves from any position. There is a mate that takes more than 50 moves; N+N+P+K v K I think. In this case the 50 move rule is extended.

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KRNKNN can be up to 250 moves! I wonder if you can claim a draw by the 50 move rule, or the referee will say you can play on because progress has been made (the reason for the 50 move rule is to suspend a game that hasn't made any progress)

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If no pawn move or capture has been made within 50 moves draw can be claimed even if there is a forced mate in the 51st move.

The importent thing in otp play is to stop the clock, call the referee and tell which move you will make to make the 50th move. If you move you lost your right to claim the draw until your opponent has moved (without moving a pawn or capture something).

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Originally posted by Kaoslos
If no pawn move or capture has been made within 50 moves draw can be claimed even if there is a forced mate in the 51st move.

The importent thing in otp play is to stop the clock, call the referee and tell which move you will make to make the 50th move. If you move you lost your right to claim the draw until your opponent has moved (without moving a pawn or capture something).
I found this on the net:

"What's the 50-move rule? If a game continues 50 moves without a Pawn move or a capture, the game is drawn. That means 50 moves for White and 50 moves for Black.

In recent years the rules have been changed to allow more than 50 moves when certain material is left on the board. This is because computers have discovered endgame positions which are a theoretical win, but which take more than 50 moves against the best defense. These positions are very rare and are not likely to occur in your games. Unless you are playing in a tournament where the director has specified rules for these special positions, use the 50-move rule."