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Subject: Re: triangular array vs. walking the hash table

Author: Michael Henderson

Date: 21:28:06 09/19/04

Go up one level in this thread


On September 20, 2004 at 00:00:57, Stuart Cracraft wrote:

>On September 19, 2004 at 20:21:57, Michael Henderson wrote:
>
>>On September 19, 2004 at 19:26:25, Stuart Cracraft wrote:
>>
>>>On September 19, 2004 at 19:11:51, Michael Henderson wrote:
>>>
>>>>On September 19, 2004 at 18:55:25, Stuart Cracraft wrote:
>>>>
>>>>>On September 19, 2004 at 17:51:05, Michael Henderson wrote:
>>>>>
>>>>>>On September 19, 2004 at 17:04:14, Stuart Cracraft wrote:
>>>>
>>>>>>>  2) is the above normal that walking the hash gives sometimes
>>>>>>>     a longer pv?
>>>>>>
>>>>>>perfectly normal since many people use hash to "extend" their PV's
>>>>>>
>>>>>
>>>>>Not sure I understand.
>>>>
>>>>The length of the PV using hash tables is variable because you don't know the
>>>>length of the PV...you just keep probing the hash until you can't get anything
>>>>useful out of it.
>>>>
>>>>for example:
>>>>triangular array PV: A B C D E
>>>>walking the hash PV: A B C D E F G
>>>>
>>>>you got move F because you probed position E and found a good move to print.
>>>>Move G from probing position F. Triangular array PV has a definite depth--search
>>>>depth limited.
>>>>
>>>>
>>>>>
>>>>>>
>>>>>>>
>>>>>>>  3) I update my triangular array in the main search and the
>>>>>>>     quiescence search. reasonable?
>>>>>>
>>>>>>yes.  The problem with qsearch is that it's just "cleanup"--considers only
>>>>>>certain types of moves.  So qsearch section of the PV might contain some stupid
>>>>>>moves you might not want to display.  There's nothing wrong with knowing what
>>>>>>your qsearch is doing, though...
>>>>>
>>>>>More information is never less, to be sure.
>>>>>
>>>>>>
>>>>>>>
>>>>>>>  4) Anything else you can think of.
>>
>>Ok these are some random but relevant questions:
>
>>1. When you make a two-square pawn move, and the opponent cannot make an ep
>>capture, do you hash-xor the "target" ep square in the hash table?
>
>Currently no special handling is done for the hash table in regards to
>enpassant. That information is not recorded in any way.
>
>>2. When you get a null move cutoff at a node and store in the hash table, do you
>>store NULLMOVE as the move in the hash table, or do you store the move from the
>>hash probe at this node?
>
>When the null move score is >= beta, I am returning
>from the search routine immediately. No hash store.
>
>Stuart

I highly recommend trying it, null move cutoffs are a major portion of your
search! Storing them will give you a speedup esp with 1-tier, 1 second searches.
 Now tell me your WAC results :)

Michael



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