Author: Don Dailey
Date: 06:08:45 01/14/98
Go up one level in this thread
Hi Stuart, I'll bet square of the pawn differs significantly in what it adds to each program. I'm guessing that if you don't have good passed pawn heuristics it will make a bigger difference. When I specifically tested it a previous program it did not show up as being a big deal. But most programs probably have bonuses for getting the king closer to passed pawns (which mine does) and this may tend to serve the same function (but not nearly as precise.) But it's still very important to have this heuristic in my opinion. You WILL definitely lose and draw games you didn't need to. When it shows up it really does put your program in a different class and it's easy to implement the basic algorithm. There are some fine points you may want to cover later though like recognizing pawn races but you'll get 90% of the benefit with the simple version of square of pawn. I don't remember the test results specifically but I do remember it was enough to measure with little trouble. This implies at least 20 rating points but it could be somewhat more. But 20 rating points is a lot, a couple 20 pointers and you have a noticably better program. - Don On January 13, 1998 at 21:25:00, Stuart Cracraft wrote: >Okay -- then how much strength, if any, is square-of-the-pawn >giving to the latest version of your program? When you drop this >feature from the program, what does the rating fall/rise to? --Stuart > >On January 13, 1998 at 14:30:40, Robert Hyatt wrote: > >>On January 13, 1998 at 12:57:43, Stuart Cracraft wrote: >> >>>Years ago I remember reading something where Dan and Kathe Spracklen >>>(remember them?) said that the addition of the square-of-the-pawn >>>rule-of-thumb to their program increased is strength significantly. >>>(I think they said a whole USCF class!) >> >>It wasn't Dan and Kathe, it was me. This was something I added to >>"blitz" around 1970 or so. Back then, it was searching 4-5 plies >>max, and had a USCF rating of around 1400, playing in local tournaments. >>But it kept getting hoodwinked in endings where the opponent would offer >>something to decoy the king away, and then the pawn could scamper in >>before the king could catch it. It was winning middlegames, but losing >>endgames. Remember too, that this was in the days of 4-5 plies of >>selective search, with *no* extensions and not even a real quiescence >>search. So this was a critical issue. >> >>When I put this in, its overall rating climbed to 1600, and stuck there >>until I "went exhaustive" in 1977 when its rating jumped to 1800+, and >>then when I "went Cray" in 1980 we went to 2200+. (All official USCF >>rating numbers, not TPR or something else). >> >> >>> >>>Anyway, now that I have passed pawns stored in my pawn transposition >>>table, it would be simple to use them in some calculation to get a >>>square-of-the-pawn assessment. >>> >>>How have you implemented square-of-the-pawn? Are there any strange >>>implementation issues or things to watch for? What kind of strength >>>improvement did your program get and how did you determine this >>>strength improvement. >>> >>>Thanks ahead! >>> >>>Stuart >> >>The issue is only "can the king catch the pawn?" If the answer is no, >>score+=queen-pawn, if the answer is yes, then there's no bonus. You >>still >>need a search, because it is possible to have two passers, neither of >>which >>can outrun the king, but neither of which can be captured either because >>capturing one takes you out of the square of the other...
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