Author: rasjid chan
Date: 04:45:51 04/06/04
Go up one level in this thread
On April 06, 2004 at 05:28:54, Sune Fischer wrote:
>
>>> else Record(a,ALPHA_FLAG,0);
>>Here may be the problem and here you deviate from the "full fail-soft"
>>model as you did not collect the best of the scores < alpha.
>>
>>I actually made this post because of the way I do fail-soft and I am not
>>sure yet I got it right and it posed problems.
>>
>>My answer
>>=========
>>
>>Let x_eval = eval() score for the node.(so cannot ignore standpat )
>>let best_searched_score be the best score for all moves searched.
>>
>>best_searched_score <= alpha
>
>You should keep a best_searched_score and check for this independently of
>alpha. Initialize it to x_eval and if score>best_searced_score you update the
>best_searched_score along with alpha.
>
>>so either :-
>>a) alpha = x_eval (when set after eval() )
>>b) x_eval < alpha (when no alpha improvement and this is your a0)
>
>yes, adjusting alpha to x_eval would be good.
>
>>my hash is as follow:-
>>
>>if (x_eval >= best_searched_score){
>> storehash(x_eval, EXACT, depth = 0);
>> return x_eval;//****** fail low
>>}
>>
>>storehash(best_searched_score, UPPER_BOUND, depth =0);
>>return best_searched_score;//****** fail low
>>
>>Two different way to fail low, but I like exact more than upper bound
>
>You shouldn't return on an exact score if you have more moves to search, so this
>goes to the end of the search.
>
>I would write it as:
>
>if (best_searched_score > alpha_origial){
> storehash(best_searched_score, EXACT, depth = 0);
>} else {
> storehash(best_searched_score, UPPER_BOUND, depth =0);
>}
>return best_searched_score; //****** fail low or exact
>
>-S.
>>These are the subtleties (or erroneous method) I find.
>>
>>Rasjid
I think the misunderstanding is about how we store hash and how we
retrieved what is stored. THEY MUST BE CONSISTENT.
The hashing of exact for QS , depth == 0 enables me to immediately return
if ONLY WHEN I PROBE FROM QS and not in full search.
Thanks
Rasjid
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