Author: Ed Schröder
Date: 08:31:44 09/13/04
Go up one level in this thread
On September 13, 2004 at 10:16:58, Robert Hyatt wrote:
>On September 13, 2004 at 02:55:22, Ed Schröder wrote:
>
>>On September 12, 2004 at 23:54:18, Robert Hyatt wrote:
>>
>>>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?
>>
>>Because the mate-value differs. I want my QS to return correct mate-in-x values.
>>
>>My best,
>>
>>Ed
>Mate scores should _always_ be adjusted anyway. IE adjust from
>mate-in-N-from-root to mate-in-N-from-here before storing, and adjust back on a
>hit, just like you do in the normal search...
I have seen this issue coming up again and again however I never experienced any
problem with mate-values in regard to the hash table. Every mate-value is ply
driven (see below) to distinguish its length.
static int mate_value [ ] { 0, 100000, 99999, 99998, 99997 .... };
These values go right into the HT without any adjustment.
Ed
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