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Subject: Re: Blathy problem - mate in 16

Author: Ross Boyd

Date: 02:57:41 04/18/05

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>>>Which makes me think a low legal move count would be a better indicator of when
>>>to avoid null moving, rather than the usual "if (total_side_to_move_pieces < x)"
>>>condition. I think Movei generates legal moves and so is able to use this
>>>method.
>>>
>>>Food for thought,
>>>
>>>Ross
>>
>>Yes
>>
>>Movei is using that method but unfortunately it cannot solve it in a reasonable
>>time probably because of other tricks that I use that may help in games but not
>>at test suites.
>>
>>Latest Movei does not see the mate at depth 17 and the branching factor from
>>depth 14 is very bad.
>>
>>It needs
>>20490 nodes to finish depth 14.
>>234720 nodes to finish depth 15.
>>3524639 nodes to finish depth 16.
>>54218505 nodes to finish depth 17.
>>
>>Uri

Hmmm... that's a lot of nodes... if I recall correctly you don't do hash table
cuts, so that might explain the low depth. TRACE doesn't solve it either, and
gets to ply 40 almost instantly with a draw score only. If I switch off null
move, then it takes about 12 seconds (P3-600) to find the mate. Not sure now
what depth was needed.

Ross


>
>I can add 860366286 nodes to finish depth 18 with 0.00 evaluation.
>
>public movei not signioficantly different
>3524852 nodes to finish depth 16
>54297529 nodes to finish depth 17
>
>Other interesting positions to test and still not easy for movei
>
>8/8/8/2p5/1pp5/brpp3P/qpprp3/1nkbK3 w - - 0 1
>
>8/7P/8/2p5/1pp5/brpp4/qpprp3/1nkbK3 w - - 0 1
>
>I am afraid too many check extensions prevent movei to go deep and solve the
>position.

>
>Uri






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