Search found 3557 matches

by lkaufman
Wed Jan 12, 2011 5:22 pm
Forum: Computer Chess Club: Programming and Technical Discussions
Topic: Using SEE to prune in main search
Replies: 37
Views: 6693

Re: Using SEE to prune in main search

[quote I reduce the first move searched by 1 ply, but only if it is not a hash move, a good capture nor a killer. " I don't know of any other program that will reduce the very first move other than at cut nodes. Did you also test reducing starting at the second move, and if so how much better was i...
by lkaufman
Wed Jan 12, 2011 6:02 am
Forum: Computer Chess Club: Programming and Technical Discussions
Topic: Using SEE to prune in main search
Replies: 37
Views: 6693

Re: Using SEE to prune in main search

I think I remember reading that you currently just reduce the second move a full ply and the third and remaining moves two full plies, with the usual check/capture exceptions. If that is correct, I would bet that you would get an Elo gain by only allowing a single ply reduction for SEE-losing captur...
by lkaufman
Wed Jan 12, 2011 2:02 am
Forum: Computer Chess Club: Programming and Technical Discussions
Topic: Using SEE to prune in main search
Replies: 37
Views: 6693

Re: Using SEE to prune in main search

Are you saying that you reduce them just as if they were losing (SEE) non-checks? If so that seems wrong to me, because checks are always worth looking at more than they would be if they were not checks, since the number of replies is so much smaller. Perhaps you just do more conservative reduction...
by lkaufman
Mon Jan 03, 2011 4:56 pm
Forum: Computer Chess Club: Programming and Technical Discussions
Topic: lmr in PV
Replies: 17
Views: 4553

Re: lmr in PV

Since you don't distinguish node types for LMR, what are your conditions are how much do you reduce? I think the general conclusion of all the top rated programs outside the Rybka/robo family is that it does pay to reduce regardless of node type, but it pays to reduce less at PV nodes. I can't justi...
by lkaufman
Mon Jan 03, 2011 3:18 pm
Forum: Computer Chess Club: Programming and Technical Discussions
Topic: lmr in PV
Replies: 17
Views: 4553

Re: lmr in PV

Yes, we do lmr in PV in Komodo. Yes, we know what works in Komodo, the question is what there is about Rybka, Robo and related programs that makes them reject LMR in PV while SF, Komodo and many others use it?
by lkaufman
Mon Jan 03, 2011 3:19 am
Forum: Computer Chess Club: Programming and Technical Discussions
Topic: lmr in PV
Replies: 17
Views: 4553

Re: lmr in PV

Thanks. I based my conclusion only on Rybka, Robo, Ippo, and Fire. I didn't realize that Ivanhoe was that different from Fire for example. Still, I wonder why the others all rejected LMR in PV when it is standard in all the unrelated top programs.
by lkaufman
Mon Jan 03, 2011 12:52 am
Forum: Computer Chess Club: Programming and Technical Discussions
Topic: lmr in PV
Replies: 17
Views: 4553

lmr in PV

Why is it that most recent strong programs do LMR in PV with success (Stockfish even having increased the reductions in the new version), but Rybka and all the programs said to be derived from Robolito do not do LMR in PV? I'm sure it doesn't work in those programs or they would be doing it, but wha...
by lkaufman
Mon Dec 20, 2010 7:43 pm
Forum: Computer Chess Club: General Topics
Topic: What program first made decisions by node-type?
Replies: 6
Views: 1045

Re: What program first made decisions by node-type?

No, I'm just curious about who should get credit for these ideas. I am writing a chess book, but not on computer chess.
by lkaufman
Mon Dec 20, 2010 4:29 am
Forum: Computer Chess Club: General Topics
Topic: What program first used hard pruning?
Replies: 38
Views: 8474

Re: What program first used hard pruning?

Do you know when the idea of different extension or reduction rules for PV and non-PV nodes was introduced?
by lkaufman
Sun Dec 19, 2010 6:12 am
Forum: Computer Chess Club: General Topics
Topic: What program first made decisions by node-type?
Replies: 6
Views: 1045

What program first made decisions by node-type?

Which is the first program known to make distinctions in its search algorithms between PV nodes and non-PV nodes? This could be different extensions or different reductions based on node type. I don't recall hearing of this prior to the 2000s, but I could well be wrong.