Houdini and Gaviota Tablebases

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brinan
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Houdini and Gaviota Tablebases

Post by brinan » Sat Dec 18, 2010 2:19 pm

Robert

No Access When Black To Move

Within Arena GUI v2.0.1, set up kr v krp endgame. When analysing, Houdini 1.5 immediately responded when White to move, but not so on Black's turn. Instead, started analysing.

Tried Critter 0.90. Responded straight away regardless of whether White or Black to move.

Regards.
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Uri Blass
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Re: Houdini and Gaviota Tablebases

Post by Uri Blass » Sat Dec 18, 2010 3:10 pm

brinan wrote:Robert

No Access When Black To Move

Within Arena GUI v2.0.1, set up kr v krp endgame. When analysing, Houdini 1.5 immediately responded when White to move, but not so on Black's turn. Instead, started analysing.

Tried Critter 0.90. Responded straight away regardless of whether White or Black to move.

Regards.
I did not install gaviota tablebases but the behaviour that you describe is logical and I suspect that it is not about white and black but about material advantage.

In drawn positions the best thing is simply to play the drawing move if you are the inferior side but if you have the advantage it is better to calculate and not use the tablebases because there is a chance that your opponent is going to make a mistake.

brinan
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Re: Houdini and Gaviota Tablebases

Post by brinan » Sat Dec 18, 2010 4:52 pm

Uri Blass wrote: [...] In drawn positions the best thing is simply to play the drawing move if you are the inferior side but if you have the advantage it is better to calculate and not use the tablebases because there is a chance that your opponent is going to make a mistake.
Logical. Guess author of Critter took a different view.

Thanks Uri.
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Houdini
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Re: Houdini and Gaviota Tablebases

Post by Houdini » Sat Dec 18, 2010 5:53 pm

brinan wrote:Robert

No Access When Black To Move

Within Arena GUI v2.0.1, set up kr v krp endgame. When analysing, Houdini 1.5 immediately responded when White to move, but not so on Black's turn. Instead, started analysing.

Tried Critter 0.90. Responded straight away regardless of whether White or Black to move.

Regards.
That behaviour is "as designed", you'll find the following explanation on the [url=htpp://www.cruxis.com/chess/houdini.htm]Houdini web page[/url]:

Houdini will always probe the EGTB for the initial position of the search.
If an EGTB mate position is identified, the full main line will be shown immediately.
If the initial position is an EGTB draw but Houdini has a material advantage, Houdini will still play for a win - the opponent might be human or an engine without end game table bases.

brinan
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Re: Houdini and Gaviota Tablebases

Post by brinan » Sat Dec 18, 2010 8:05 pm

Houdini wrote: [...] If the initial position is an EGTB draw but Houdini has a material advantage, Houdini will still play for a win - the opponent might be human or an engine without end game table bases.
Thanks Robert for explanation (should have checked your site).

My concern stemmed from watching DR4 and Houdini laboriously play out this ending, with Rybka recognising the draw and Houdini apparently not. Could not adjudicate a draw in case of time forfeit (both engines limited to 90 minutes).

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Houdini
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Re: Houdini and Gaviota Tablebases

Post by Houdini » Sat Dec 18, 2010 8:14 pm

I see, if both engines use EGTB it's obviously quite silly to try to play for a win.
Maybe I should add a UCI option to control this behaviour.

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