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Subject: Re: No explosions

Author: Uri Blass

Date: 04:24:32 01/13/02

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On January 13, 2002 at 07:11:31, Sune Fischer wrote:

>On January 13, 2002 at 06:55:14, Uri Blass wrote:
>
>>On January 13, 2002 at 06:48:22, Sune Fischer wrote:
>>
>>>On January 13, 2002 at 05:14:44, Uri Blass wrote:
>>>
>>>>>>If you find the legal moves incrementally, how can you check for
>>>>>>numberofmoves==1 at the first move, or do you simply forget about it then?
>>>>>>
>>>>>
>>>>>In the case of check, I create only check evasions, that is, _real_ legal moves.
>>>>>Partly because it is faster for move generation, and partly because it makes the
>>>>>check for this extension a lot faster.
>>>>>
>>>>>>And why the inCheck and numberOfMoves==1, can't you forget about the inCheck and
>>>>>>just extend +1 if there is only one legal move?
>>>>>
>>>>>No because I only do it of there's a check also. I don't generate real legal
>>>>>moves at all nodes, only check nodes.
>>>>
>>>>If I understand correctly numberofMoves means number of legal moves when you are
>>>>in check
>>>
>>>Yes
>>>
>>>>and number of pseudo legal moves when you are not in check.
>>>
>>>I'm not sure how he does that, I think he finds the moves incrementally which is
>>>faster than generating all the moves. It would be a problem then to know how
>>>many possible moves there are, which is why he needs the inCheck condition.
>>>
>>>I do it differently, I almost never generate only legal moves. I simply do not
>>>know when the king is in check (I don't use bitboards for movegen), so I have to
>>>go one ply deeper to see if the king is captured. This will lead to trouble at
>>>some point, so I'm thinking of changing it.
>>>
>>>>In this case you still can extend +1 only if NumberofMoves=1 because the only
>>>>case when Numberofmoves=1 the number of legal moves is always at most 1(it can
>>>>be also 0 in some stalemate situations when there is only 1 pseudo legal move)
>>>
>>>There will be more than 1 pseudo legal move if there are more than one attacked
>>>square around the king.
>>
>>I understand it but my point is that numberofmoves=1 when the king is not in
>>check means exactly one pseudolegal move and it means at most 1 legal move.
>
>But how will he now that numberofmoves=1 if he finds them incrementally?
>If king not inCheck -> first try the hashmove, then......
>When he is about to try the hashmove, he has no idea about the number of pseudo
>moves.

You are right
I undertsand the problem and in this case numberofmoves may be 1 only because of
the fact that he did not generate all the pseudo legal moves.

Uri



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