Author: Harald Lüßen
Date: 06:22:26 04/08/04
Go up one level in this thread
On April 08, 2004 at 09:14:21, Daniel Shawul wrote:
>On April 08, 2004 at 09:04:15, Harald Lüßen wrote:
>
>>On April 08, 2004 at 07:10:29, Daniel Shawul wrote:
>>
>>>Hi
>>>Here are some questions
>>>
>>>2.In Ed's paper there are some tricks done at horizon.
>>> trick one if(score - (margin + largest hanging piece) > beta)
>>> don't do quiescence
>>> trick two if(score - 900 > beta)
>>> don't do quiescence
>>> My question is every body does
>>> score=eval()
>>> if(score > beta)
>>> don't do quiescence;
>>> So i don't see how the tricks work?
>>
>>His alpha is our beta and vice versa.
>>
>>I do:
>>int search( depth, alpha, beta )
>>{
>> score = evaluate();
>> // pruning tricks here
>> while ( moves )
>> {
>> do_move();
>> score = -search( depth-1, -beta, -alpha );
>> undo_move();
>> }
>>}
>>
>>Ed perhaps does:
>>int search( depth, alpha, beta )
>>{
>> while ( moves )
>> {
>> do_move();
>> score = evaluate();
>> // pruning tricks here
>> score = -search( depth-1, -beta, -alpha );
>> undo_move();
>> }
>>}
>>
>>Translated to my function his tricks would look like:
>>trick one if(score + margin + opponents_largest_hanging_piece < alpha)
>> don't do quiescence
>>trick two if(score + 900 < alpha)
>> don't do quiescence
>
>That is better and understandable.But isn't this similar to delta pruining?.
May be. What is 'delta pruning'? I know it as 'futility pruning'.
>But are you sure he means alpha when he says beta in all the paper. in lazy
>eval,futility etc. I shall have to check that again.
No, I am not sure. I just remember many people had these problems
with his paper. There may be parts in the above example functions
where we are in the same state of who is who. If he talks about
his tricks there, alpha=alpha and beta=beta. Always try to
understand before you implement. (This sounds very wise but in fact
I do my coding as a real dirty try and error hacker myself :-)
>>And that I can understand.
>>
>>Harald
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