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optimal aspiration window for stockfish question
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Robert Hyatt



Joined: 27 Feb 2006
Posts: 20315
Location: Birmingham, AL

PostPost subject: Re: optimal aspiration window for stockfish question    Posted: Thu Mar 15, 2012 5:30 pm Reply to topic Reply with quote

On this topic, here is another test I ran (not a cluster test.)

I took the original ippolit aspiration re-search window adjustment code as given previously. Only change I did make was that once the delta value hit 10 pawns, I set it to + infinity to avoid an extra re-search or two when looking for a mate.

For the second version, I started with Uri's suggestion of delta *= 2, which ramps it up quicker.

The first test showed that too many re-searches can be bad. Fine 70, searched to depth=45. Here's the two summary lines, with Uri's idea last:

log.001: time=9.62 mat=1 n=39906118 fh=92% nps=4.1M
log.002: time=1.19 mat=1 n=5520897 fh=98% nps=4.6M

Ignore the NPS since the second one ran so much faster, that is likely more rounding noise than actual data. But notice the node counts. The more conservative window widening takes 8x more nodes than the delta *= 2 approach. Since this is about fail high/fail low rather than normal positions, I tried a couple of others...

wac 141 (which is pretty easy of course):

log.001: time=0.40 mat=-1 n=1180277 fh=85% nps=3.0M
log.002: time=0.29 mat=-1 n=855712 fh=84% nps=3.0M

Here's one with no fail highs or lows, just to show identical behavior in that case:

log.001: time=14.30 mat=0 n=35929279 fh=93% nps=2.5M
log.002: time=14.34 mat=0 n=35929279 fh=93% nps=2.5M

Win at chess 2 which scatters a few fail highs here and there:

log.001: time=4.95 mat=0 n=15058005 fh=93% nps=3.0M
log.002: time=4.59 mat=0 n=13847564 fh=92% nps=3.0M

I will queue this up for a cluster test as well, although I don't expect much difference overall. 30K games might not be enough to show it is clearly better, but it does look better.

There are known positions where you can relax a bound too far and get into trouble. For example, if you fail high in a complex tactical position, but you are just going to gain a positional edge, if you relax the beta bound too far, suddenly you quit pruning mates that are not forced, which can explode the tree. But these appear to not be common in real games...
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Subject Author Date/Time
optimal aspiration window for stockfish question Uri Blass Mon Mar 12, 2012 11:14 am
      Re: optimal aspiration window for stockfish question Ed Schroder Mon Mar 12, 2012 12:55 pm
            Re: optimal aspiration window for stockfish question Marco Costalba Mon Mar 12, 2012 6:47 pm
                  Re: optimal aspiration window for stockfish question Don Dailey Mon Mar 12, 2012 9:41 pm
                        Re: optimal aspiration window for stockfish question Robert Hyatt Wed Mar 14, 2012 10:18 pm
                              Re: optimal aspiration window for stockfish question Marco Costalba Thu Mar 15, 2012 6:15 am
                                    Re: optimal aspiration window for stockfish question Robert Hyatt Thu Mar 15, 2012 2:06 pm
                                          Re: optimal aspiration window for stockfish question Robert Hyatt Thu Mar 15, 2012 5:30 pm
                                                Re: optimal aspiration window for stockfish question Robert Hyatt Thu Mar 15, 2012 8:11 pm
                                                      Re: optimal aspiration window for stockfish question (update Robert Hyatt Thu Mar 15, 2012 9:55 pm
                                                            Re: optimal aspiration window for stockfish question (update Miguel A. Ballicora Thu Mar 15, 2012 10:23 pm
                                                                  Re: optimal aspiration window for stockfish question (update Robert Hyatt Fri Mar 16, 2012 3:29 am
                                                                        Re: test results Robert Hyatt Fri Mar 16, 2012 3:41 am
                                                                              Re: test results Rémi Coulom Fri Mar 16, 2012 8:38 am
                                                                                    Re: test results Robert Hyatt Fri Mar 16, 2012 5:20 pm
                                                                              Re: test results Karlo Bala Jr. Fri Mar 16, 2012 11:30 am
                                                                                    Re: test results Robert Hyatt Fri Mar 16, 2012 5:26 pm
                                                                                          Re: test results Ed Schroder Fri Mar 16, 2012 6:31 pm
                                                                                          Re: test results Robert Hyatt Fri Mar 16, 2012 7:16 pm
                                          Re: optimal aspiration window for stockfish question Vincent Diepeveen Sat Mar 17, 2012 1:44 pm
                                                Re: optimal aspiration window for stockfish question Robert Hyatt Sat Mar 17, 2012 4:11 pm
                                                      Re: optimal aspiration window for stockfish question Marco Costalba Sat Mar 17, 2012 5:28 pm
                                                            Re: optimal aspiration window for stockfish question Robert Hyatt Sun Mar 18, 2012 3:28 am
                                                                  Re: optimal aspiration window for stockfish question Lucas Braesch Sun Mar 18, 2012 5:55 am
                                                                        Re: optimal aspiration window for stockfish question Joona Kiiski Sun Mar 18, 2012 9:02 am
                  Re: optimal aspiration window for stockfish question Robert Houdart Mon Mar 12, 2012 10:44 pm
                        Re: optimal aspiration window for stockfish question Robert Houdart Tue Mar 13, 2012 9:18 am
                              Re: optimal aspiration window for stockfish question Uri Blass Tue Mar 13, 2012 10:12 am
                                    Re: optimal aspiration window for stockfish question Karlo Bala Jr. Wed Mar 14, 2012 7:46 pm
                                          Re: optimal aspiration window for stockfish question Robert Hyatt Thu Mar 15, 2012 9:49 pm
                  Re: optimal aspiration window for stockfish question Lucas Braesch Wed Mar 14, 2012 4:10 pm
                        Re: optimal aspiration window for stockfish question Eelco de Groot Wed Mar 14, 2012 7:30 pm
                              Re: optimal aspiration window for stockfish question Lucas Braesch Thu Mar 15, 2012 2:03 am
                                    Re: optimal aspiration window for stockfish question Marco Costalba Thu Mar 15, 2012 6:13 am
      Re: optimal aspiration window for stockfish question Eelco de Groot Tue Mar 13, 2012 10:20 am
            Re: optimal aspiration window for stockfish question Uri Blass Tue Mar 13, 2012 12:57 pm
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