Author: Steffen Jakob
Date: 14:26:44 12/08/03
Go up one level in this thread
On December 08, 2003 at 17:20:19, Alvaro Jose Povoa Cardoso wrote:
>On December 08, 2003 at 16:50:09, Steffen Jakob wrote:
>
>>On December 08, 2003 at 16:19:48, Tim Foden wrote:
>>
>>>On December 08, 2003 at 11:02:22, Alvaro Jose Povoa Cardoso wrote:
>>>
>>>>
>>>>I've been thinking about the efficiency of the history heuristic at high search
>>>>depths.
>>>>It seems to me that the history table will be overwritten many times if we have
>>>>a search of several billions of nodes. Additionally, as the search moves to
>>>>different parts of the tree the history table values will be somewhat trashed.
>>>>What do you think we could do about this?
>>>>Maybe limit the history heuristic to a certain depth (ex: the nominal depth).
>>>>
>>>>Comments anyone?
>>
>>Hi Tim!
>>
>>I hope you enjoyed your trip back to spain. :-)
>>
>>>What happens in GLC is whenever it increments a value in the history table it
>>>checks it against a maximum. If the maximum value is exceeded, it divides all
>>>values in the table by 2.
>>
>>I do almost the same! I don´t modify the values in the table but remember a
>>shift value which is used to reduce the history values on demand:
>>
>>int historyShift = 0;
>>
>>inline Value getLimitedHistoryValue(Value historyValue) {
>> Value limitedValue = historyValue >> historyShift;
>> if (limitedValue > MAX_HISTORY_VALUE) {
>> historyShift++;
>> limitedValue = limitedValue >> 1;
>> }
>> return limitedValue;
>>}
>>
>>In the past I didn´t limit the history value. Then I realized that it became a
>>dominant sort criterium in deep searches which was of course very bad.
>>
>>Best wishes,
>>Steffen.
>
>Do you reset historyShift?
>If so, when?
I reset this variable only if a new game starts.
Greetings,
Steffen.
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