Shame
Moderators: hgm, Rebel, chrisw
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- Posts: 243
- Joined: Sat Mar 11, 2006 8:31 am
- Location: Malmö, Sweden
- Full name: Bo Persson
Re: Shame
At least it's one reason. Your Queen needs the support of her king to be able to mate the other king along the edge of the board. They should both close in on him to restrict his movements.Henk wrote:I just found out that my engine can not finish a KQK end game. PSQ table says that King should stay in center. Don't know if that's the only reason.
So there is some room for improvement.Henk wrote:My engine also does not know that KK is a draw.
When fixing this, you might consider that without a Q or R, you probably have a draw long before reaching KK.
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- Posts: 7220
- Joined: Mon May 27, 2013 10:31 am
Re: Shame
Even simple alpha beta search can go wrong. I forgot to try best move from previous iteration first but returning best move found so far that is stored in TTable. So once in a while if time is up you get really bad moves. For search did not end and it did not try move from previous iteration first.
Also mate scores may not be stored and retrieved right from TTable.
Also mate scores may not be stored and retrieved right from TTable.
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- Posts: 4052
- Joined: Thu May 15, 2008 9:57 pm
- Location: Berlin, Germany
- Full name: Sven Schüle
Re: Shame
Let us guess more of these three lines, then we can try to guess the bug ...Henk wrote:Strange alpha beta search with TTable is able to solve this easily while PVS can't. Difference is only three lines of code. After a few moves the algorithm should see a mate in eight or so.
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- Posts: 7220
- Joined: Mon May 27, 2013 10:31 am
Re: Shame
My guess is it that it had something to do with TTable. As always. No TTable no bugs.Sven Schüle wrote:Let us guess more of these three lines, then we can try to guess the bug ...Henk wrote:Strange alpha beta search with TTable is able to solve this easily while PVS can't. Difference is only three lines of code. After a few moves the algorithm should see a mate in eight or so.