Author: Renze Steenhuisen
Date: 08:45:33 04/07/04
Go up one level in this thread
>>>>>>>How important is it to hash in the castling rights and en-passant fields?
>>>>>>
>>>>>>Very important; it will go wrong at a tournament otherwise.
>>>>>
>>>>>Yes, I read of some (your?) tournament issue?
>>>>>
>>>>>But is it important for my results, now? Because I am using the starting
>>>>>position as test position...
>>>>
>>>>If you search above a ply or 4 sure, as then you can already start capturing en
>>>>passant.
>>>
>>>Should I put it in first, could that really be the problem?
>>
>>Depends upon how you measures errors/collissions.
>
>>Define collision first.
>>
>>(1) two different positions produce the same hash signature...
>>
>>(2) two different hash signatures address the same table entry...
>>
>>(1) should not happen with 64 bit signatures. (2) is common and is why the
>>replacement strategy is so important.
>
>I defined collision somewhere in this thread but it is the same as (1):
>
>from code of DarkSight which is comparable with next.c in Crafty
>/********************/
>
> case HASH_MOVE:
> if( a tt_move is provided )
> {
> tree->stats.hashkey_requests++;
> if( provided tt_move is valid move )
> return tt_move;
> else
> tree->stats.hashkey_collisions++;
> }
>
>/********************/
>
>When I search from the starting position I get:
> tree->stats.hashkey_collisions = 34
> tree->stats.hashkey_requests = 38503
>
>Or to give the complete output...
>
>nodes searched-> 4651507
>qnodes/nodes_searched-> 0.24
>capture moves-> 0
>evaluations done-> 4150454
>first fail highs-> 220020
>fail highs-> 257405
>move-ordering: 85.48
>NULL-move fail-highs-> 903676
>tt_probes-> 1367771
>tt_hits-> 139286
>tt hit-ratio: 10.18
>TT overwrites-> 87645
> number of LOWERbounds-> 257405
> number of EXACTbounds-> 499
> number of UPPERbounds-> 115898
>hashkey collisions: 34 / 38503 = (0.0009)
>ptt_probes-> 4150454
>ptt_hits-> 3627474
>ptt hit-ratio: 87.40
>PTT overwrites-> 481427
>PTT key collisions-> 82819
>Futility Prunings-> 287703
>EXTENSIONS:
> Check Ext: 39065
> Mate Threat Ext: 27
> Single Reply Ext: 0
> Pushed Pawn Ext: 1086
> Recapture Ext: 31824
> Singular Ext: 0
>captures: 374765
>normals : 228993
>norm/caps: 0.61
Sorry, forgot to mention it is for a 10 ply search...
Renze
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