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Subject: Re: What are psuedo-legal moves?

Author: Peter Kappler

Date: 17:29:28 04/27/99

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On April 27, 1999 at 19:58:50, James Robertson wrote:

>On April 27, 1999 at 18:30:16, Peter Kappler wrote:
>
>>On April 27, 1999 at 17:35:15, KarinsDad wrote:
>>
>>>On April 27, 1999 at 15:35:06, Will Singleton wrote:
>>>
>>>[snip]
>>>>
>>>>Amateur doesn't find the move after 2 minutes and 9 ply, liking Be7 with +3.  I
>>>>better get busy and try out the single-reply extension.  Problem is, I use
>>>>psuedo-legal moves, so I'm not sure how to tell when I only have one reply!
>>>>
>>>>Will
>>>
>>>The subject says it all.
>>>
>>>KarinsDad :)
>>
>>
>>Most simple move generators ignore the status of the king (i.e. is it in check,
>>does this move place it in check?) and just generate every possible move in the
>>position.  The test for legality is resolved by the search.
>>
>>--Peter
>
>Also, it is much faster (I think). But, you do have the one reply to check
>problems. Crafty generates pseudo-legal moves and has one-reply to check
>extensions, I think. How does it handle this?
>
>James


Here's how I think Crafty does it:

In general, Crafty just generates pseudo-legal moves, *unless* it already knows
it is in-check, in which case it uses a special "check-evasion" move-generator
that will generate only legal replies to check.

Again, this is just my recollection.  Wish Bob were here.  :-(

--Peter




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