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How to get futility pruning to work?
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Ferdinand Mosca



Joined: 10 Aug 2008
Posts: 450
Location: Philippines
PostPost subject: Re: How to get futility pruning to work?    Posted: Thu Mar 08, 2012 4:30 am Reply to topic Reply with quote
micron wrote:
More careful measurements of time-to-depth (in many positions) showed only a pathetic 3-5% speedup by my pruning, not the 15-25% claimed earlier. Duh, no wonder I couldn't get any Elo advantage from pruning, whose primary purpose is to reduce ttd significantly.

I've written a new function IsMoveCheck(), which is 3x faster than making the move and then testing for check.

Don wrote:
You must never prune checks when doing futility (unless you really know what you are doing)
Thank you, that's very clear.

With these improvements, I now get a definite increase in playing strength due to futility pruning. Wahoo! It's not many Elo, but tuning the margins should help. Then it will be time to try late-move pruning as well.


Quote:
More careful measurements of time-to-depth (in many positions) showed only a pathetic 3-5% speedup by my pruning, not the 15-25% claimed earlier. Duh, no wonder I couldn't get any Elo advantage from pruning, whose primary purpose is to reduce ttd significantly.

I am trying to implement some bitboard routines in my engine, and have difficulty figuring out if ttd is a good measure for improvement, though I eventually test it in real games. What specific position should one choose for doing some initial test to measure ttd? Would it be better also to add number of solutions solved? assuming that ttd is very close, by say selecting those positions where the best move has +score and the second best move has -score.
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Subject Author Date/Time
How to get futility pruning to work? Robert Purves Mon Mar 05, 2012 5:16 am
      Re: How to get futility pruning to work? Ferdinand Mosca Mon Mar 05, 2012 6:24 am
      Re: How to get futility pruning to work? Don Dailey Mon Mar 05, 2012 1:52 pm
            Re: How to get futility pruning to work? Robert Purves Mon Mar 05, 2012 10:16 pm
                  Re: How to get futility pruning to work? Don Dailey Mon Mar 05, 2012 10:42 pm
                        Re: How to get futility pruning to work? Robert Purves Wed Mar 07, 2012 11:40 pm
                              Re: How to get futility pruning to work? Ferdinand Mosca Thu Mar 08, 2012 4:30 am
                                    Re: How to get futility pruning to work? Robert Purves Thu Mar 08, 2012 8:55 am
                        Re: How to get futility pruning to work? Ferdinand Mosca Thu Mar 08, 2012 4:36 am
            Re: How to get futility pruning to work? Vincent Diepeveen Thu Mar 08, 2012 7:04 am
                  Re: How to get futility pruning to work? Robert Purves Sat Mar 10, 2012 12:38 am
                        Re: How to get futility pruning to work? Vincent Diepeveen Sun Mar 11, 2012 4:14 am
                              Re: How to get futility pruning to work? Vincent Diepeveen Sun Mar 11, 2012 4:41 am
                        Re: How to get futility pruning to work? Vincent Diepeveen Sun Mar 11, 2012 5:01 pm
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