Author: Nagendra Singh Tomar
Date: 18:12:20 10/19/02
Go up one level in this thread
See my comments inline
On October 19, 2002 at 20:37:35, Alessandro Damiani wrote:
>On October 19, 2002 at 20:34:19, Alessandro Damiani wrote:
>
>>On October 19, 2002 at 20:08:49, Nagendra Singh Tomar wrote:
>>
>>>Another question that is part of the same discussion is
>>>if(sval > alpha)
>>>{
>>> if(sval >= beta)
>>> {
>>>
>>> }
>>> alpha = sval; /* why this */
>>>}
>>>
>>>be setting alpha to sval we are telling the qsearcher that we will not be
>>>interested in any score less than the static score at the qsearch root.
>>>Why so?
>>>Normally we decide bounds on the search with a previous search done with a
>>>higher or same depth as the current search. But here we are deciding the bounds
>>>of a deeper search (qsearch) with a lesser depth search (static eval at the
>>>qsearch root).
>>>
>>>Any comments are highly welcome
>>>
>>>tomar
>>>
>>
>>this is just maximizing. by using operator "max" one would write (pseudo
>>language):
>>
>> alpha:= alpha max value
>>
>>as we know this is aquivalent to
>>
>> if alpha<value ->
>> alpha:= value
>> [] alpha>=value ->
>> skip
>> fi
>>
>>or in C:
>>
>> if (value>alpha)
>> alpha= value;
>>
>>
>>in the code you present maximazing and beta cut-off are just combined.
>>
>>Alessandro
>
>I should add that the static score is an approximation of the value for all
>non-captures. So, the maximum is at least the static score.
I believe we do qsearch to see if there are any hidden surprises (a solution for
the horizon effect). So the objective of doing a qsearch is to find whether the
current positions score is really what we think or whether there is a big
surprise which pulls it down drastically. So if we assume that the score is at
least the static score then we are losing the advantages of qsearch, the reason
at first place why we opted to do a qsearch
regds
tomar
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