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stand pat or side to move bonus
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Larry Kaufman



Joined: 10 Jan 2010
Posts: 1229
Location: Maryland USA
PostPost subject: Re: stand pat or side to move bonus    Posted: Fri Mar 23, 2012 3:26 am Reply to topic Reply with quote
Daniel Shawul wrote:
Quote:

If pieces are forked it's not obvious to me that a tempo will help in general, the damage is already done. Anyway the most critical use of an eval function is for quies, and in quies if you can capture something you just do it. So we can almost assume that the side under the more severe attack must be on move. If you have checks in quies this may also apply to "badly exposed king" though less clearly so. Stockfish bases the size of the bonus on game phase, as did Rybka 3, while I believe that Ippo, Ivanhoe, and Critter do not. In this (as in most other search issues where we have to choose between two options) we have found that Stockfish's approach works better for us than Ippo's. I'm sure that the engines that don't consider phase have a reason for this, but I can't guess what it might be.

I think the magnitude of the tempo compared to other evaluation terms should be considered. In the endgame, wins and losses are decided by small details. So applying a big tempo bonus there is risky maybe even more than the danger of having a zugzwang. Tempo is obviously important during the opening so for me a gradually decreasing bonus may work better than a constant one.

As to your original question, I prefer (A) only because it allows to adjust the bonus depending on other situations on the board. Doing it at the search as you explained it forces you to use a constant bonus since you don't call eval() there usually.

Maybe that is why Ippo don't use different bonuses. That is choosing implementation (B) forced them to use constant bonus. You never know. Either that or it is just a declaration that having the side to move is always equally good.


Rybka, Stockfish, and Komodo all agree with you on your preference for (A), and for the reasons you give (at least speaking for Rybka and Komodo). I'm sure that the authors of Ippo, Critter, Ivanhoe etc. are aware of this argument. So they must see some compensating advantage in using method (B) or (C). But what could it be?
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Subject Author Date/Time
stand pat or side to move bonus Larry Kaufman Thu Mar 22, 2012 9:15 pm
      Re: stand pat or side to move bonus Sam Hamilton Thu Mar 22, 2012 10:49 pm
      Re: stand pat or side to move bonus Daniel Shawul Thu Mar 22, 2012 11:27 pm
            Re: stand pat or side to move bonus Larry Kaufman Fri Mar 23, 2012 12:40 am
                  Re: stand pat or side to move bonus Daniel Shawul Fri Mar 23, 2012 1:27 am
                        Re: stand pat or side to move bonus Larry Kaufman Fri Mar 23, 2012 2:06 am
                              Re: stand pat or side to move bonus Daniel Shawul Fri Mar 23, 2012 3:07 am
                                    Re: stand pat or side to move bonus Larry Kaufman Fri Mar 23, 2012 3:26 am
                                          Re: stand pat or side to move bonus Richard Vida Fri Mar 23, 2012 2:07 pm
                                                Re: stand pat or side to move bonus Larry Kaufman Fri Mar 23, 2012 2:42 pm
                                                      Re: stand pat or side to move bonus Richard Vida Sat Mar 24, 2012 9:59 am
                                                            Re: stand pat or side to move bonus Larry Kaufman Sat Mar 24, 2012 2:44 pm
                                                                  Re: stand pat or side to move bonus Richard Vida Sun Mar 25, 2012 1:51 pm
                                                                        Re: stand pat or side to move bonus Larry Kaufman Sun Mar 25, 2012 2:44 pm
                                                                              Re: stand pat or side to move bonus Richard Vida Sun Mar 25, 2012 3:21 pm
                                                                                    Re: stand pat or side to move bonus Larry Kaufman Sun Mar 25, 2012 3:40 pm
                                                Re: stand pat or side to move bonus Marek Kwiatkowski Fri Mar 23, 2012 2:46 pm
                              Re: stand pat or side to move bonus Richard Vida Fri Mar 23, 2012 2:01 pm
      Re: stand pat or side to move bonus Robert Hyatt Fri Mar 23, 2012 2:38 pm
            Re: stand pat or side to move bonus Larry Kaufman Fri Mar 23, 2012 2:47 pm
                  Re: stand pat or side to move bonus Uri Blass Fri Mar 23, 2012 3:39 pm
                        Re: stand pat or side to move bonus Larry Kaufman Fri Mar 23, 2012 3:45 pm
                              Re: stand pat or side to move bonus Robert Hyatt Sat Mar 24, 2012 3:03 am
                                    Re: stand pat or side to move bonus Larry Kaufman Sat Mar 24, 2012 3:14 am
                                          Re: stand pat or side to move bonus Robert Hyatt Sat Mar 24, 2012 4:41 am
                                                Re: stand pat or side to move bonus Marco Costalba Sat Mar 24, 2012 8:12 am
                                                      Re: stand pat or side to move bonus Robert Hyatt Mon Mar 26, 2012 5:32 am
                                                            Re: stand pat or side to move bonus Sam Hamilton Mon Mar 26, 2012 2:12 pm
                  Re: stand pat or side to move bonus Robert Hyatt Sat Mar 24, 2012 3:00 am
                        Re: stand pat or side to move bonus Larry Kaufman Sun Mar 25, 2012 7:53 pm
      Re: stand pat or side to move bonus Sune Fischer Sat Mar 24, 2012 10:38 am
      Re: stand pat or side to move bonus Vincent Diepeveen Sun Mar 25, 2012 9:08 am
            Re: stand pat or side to move bonus Uri Blass Sun Mar 25, 2012 11:24 am
                  Re: stand pat or side to move bonus Vincent Diepeveen Sun Mar 25, 2012 2:15 pm
            Re: stand pat or side to move bonus Ed Schroder Sun Mar 25, 2012 1:02 pm
                  Re: stand pat or side to move bonus Larry Kaufman Sun Mar 25, 2012 7:43 pm
                        Re: stand pat or side to move bonus Ed Schroder Sun Mar 25, 2012 8:37 pm
                              Re: stand pat or side to move bonus Larry Kaufman Sun Mar 25, 2012 8:51 pm
                                    Re: stand pat or side to move bonus Richard Vida Sun Mar 25, 2012 9:33 pm
                                          Re: stand pat or side to move bonus Larry Kaufman Sun Mar 25, 2012 9:48 pm
                                          Re: stand pat or side to move bonus Don Dailey Sun Mar 25, 2012 10:15 pm
                                          Re: stand pat or side to move bonus Vincent Diepeveen Mon Mar 26, 2012 10:48 pm
                                                Re: stand pat or side to move bonus Richard Vida Tue Mar 27, 2012 9:59 am
                                                      Re: stand pat or side to move bonus Vincent Diepeveen Tue Mar 27, 2012 11:38 am
                                    Re: stand pat or side to move bonus Ed Schroder Sun Mar 25, 2012 10:39 pm
            Re: stand pat or side to move bonus Larry Kaufman Sun Mar 25, 2012 3:49 pm
                  Re: stand pat or side to move bonus Vincent Diepeveen Sun Mar 25, 2012 4:20 pm
                        Re: stand pat or side to move bonus Larry Kaufman Sun Mar 25, 2012 4:47 pm
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