Author: Stuart Cracraft
Date: 07:55:55 07/31/04
Go up one level in this thread
On July 28, 2004 at 09:04:16, Peter Alloysius wrote: > >>>>I visited Aske Plaat's site and slapped MTD(f) into my >>>>program, keeping the existing PVS/NEGASCOUNT in lieu of implementing >>>>his AlphaBetaWithMemory(). This is perfectly okay according to Aske. >>>> >>> >>>you should implement his AlphaBetaWithMemory(), or your program will take >>>9999999 iterations to find mate value. If value found by alphabeta is above beta >>>or below alpha, return that real value, not the alpha/beta. >> >>Exactly. And things do look somewhat better with the return alpha/beta >>vs. return value under conditional compilation. >> >>As the other author has pointed out, instabilities still abound with >>the current implementation and it is no where near PVSNEGASCOUT in >>performance nor reliability in its early form, obviously. >> >>But good call and a good laugh. > >I think that Plaat's AlphaBetaWithMemory() is somewhat what we called fail-soft >ab, right? (if i don't mistaken it, i'm still confused with those terms) > >with that, my mtd(f) engine *always* need only two iterations to find mate >value, one to get upperbound and another to get lowerbound. > >So, if you need hundred iteration to find mate value, then your search() surely >return alpha/beta instead of true value (in this case is mate value). Return >that true value and no need to worry about accelerator or instability in your >case. CMIIW I appreciate that and when I first heard of it went through the code and made a conditional compilation MTDF for all the return(value)'s instead of return for alpha or beta. I did that for the main search and quiescence. I need to go back in and doublecheck. As you say, perhaps implementing Plaat's ABWM is the right way to go and make that conditionally compile for MTDF as well. There never seems to be enough time for all the things for a chess program.
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