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Subject: Re: Extending Checks

Author: Robert Hyatt

Date: 20:54:18 09/12/04

Go up one level in this thread


On September 12, 2004 at 17:39:45, Ed Schröder wrote:

>On September 12, 2004 at 13:22:52, José Carlos wrote:
>
>>On September 12, 2004 at 06:50:50, Ed Schröder wrote:
>>
>>>On September 11, 2004 at 11:47:35, José Carlos wrote:
>>>
>>>>On September 10, 2004 at 21:35:58, Stuart Cracraft wrote:
>>>>
>>>>>I read, somewhere, and I forget who, about
>>>>>if 1 legal move, extend 2 ply,
>>>>>2 or more legal moves, then 1 ply.
>>>>>Anyone have any stats on the effects
>>>>>on play of the above instead of
>>>>>always extend 1 legal move. Does it
>>>>>blow up?
>>>
>>>
>>>>  I guess you read it in Ed's programming page about Rebel. He does that in
>>>>qsearch, and regarding checking moves generation.
>>>>  I tried his idea in my private program and it didn't work for me. It generated
>>>>too many nodes, but I probably did something wrong.
>>>
>>>Checks in QS works provided you hash in QS. With exploding checks hash
>>>move-ordering is crucial.
>>>
>>>My best,
>>>
>>>Ed
>
>>  I thought of this too. The problem I couldn't solve (properly) was about
>>draft. When I tried hashing qsearch in Averno (no checks in qsearch), I simply
>>stored those positions with draft = 0, as they're all equivalent.
>>  But when I tried in my other program (with checks according to your schema) I
>>couldn't use 0 as draft as remaining check-depth was important in order to give
>>a cutoff. I had two options: use draft 0 and only to store a move (no cutoff) or
>>create a different hash table only for qsearch with checks. After check-depth
>>was zero, I used again the main transposition table with draft = 0.
>>  I tried the latter and didn't work well. I should probably try using it only
>>for move ordering, with draft = 0.
>
>In my baby the draft in QS simply becomes negative, so -1, -2 etc. You can't do
>the same?
>
>Ed

You should avoid letting it go negative.  Is there any difference from a hit two
moves deep into the q-search vs 4 moves deep?  IE can you consider moves at
ply=2 that you can't consider at ply=4 in the q-search?  If not, why restrict it
so that ply=2 probe can't use a position stored at ply=4 elsewhere?





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