Author: martin fierz
Date: 07:37:21 02/24/04
Go up one level in this thread
On February 24, 2004 at 10:19:51, Anthony Cozzie wrote: >On February 24, 2004 at 09:32:08, martin fierz wrote: > >>On February 23, 2004 at 23:05:58, Robert Hyatt wrote: >> >>>On February 23, 2004 at 18:52:36, Geoff Westwood wrote: >>> >>>>Hi >>>> >>>>I was perusing the latest table of results, Crafty's static eval of 2 of the >>>>passed pawn positions were interesting. >>>> >>>>Assuming I havent made a mistake in the cutting and pasting >>>> >>>>Position 1 >>>>8/4k3/8/7P/1P6/3p4/4p3/4K3 b - -; id "PP-00004" >>>> >>>>[D]8/4k3/8/7P/1P6/3p4/4p3/4K3 b - - >>>> >>>>Crafty reckons this is +4.8 (good for white). This is rather clever as although >>>>the black king could catch either of the white passed pawns, it cannot stop >>>>both. Also blacks 2 advanced pawns cant do anything as the white king gobbles >>>>them up easily. Only Crafty and Tinker understand this position statically. Any >>>>tips on what the algorithm is to sort this one out ? >>> >>> >>>This is the idea I have reported here before, pointed out (demanded to be fixed >>>in fact) by a GM friend of mine. The idea is that the two separated pawns are >>>better than the two connected passers. The king stops the two connected passers >>>easily until the enemy king supports them, meanwhile the split passers walk on >>>in... >> >>i don't like the generality of your statemtent here, but - it is a small price >>to pay if it's right in most cases. which perhaps is the case. anyway, here's my >>question: >> >>what does your static eval say for the black king on e6/e5/e4/e3 ? i wouldn't be >>surprised if it got it wrong in some cases now... >> >>cheers >> martin > >The question is always "what do you put in the search, what do you put in the >eval" <shrug>. sort of - for me the answer is clear. the point i wanted to make (not the first time, BTW) is that returning huge evaluations in positions like this may not be a good idea because they are *very* sensitive to details like king position. e.g. if i got it right, then it's a white win with the king on e6, but a black win with the king on e5. do you really want to allow your static eval to return a white win when it might be a black win? of course you can say that if you get it right 60% of the time, it is better than returning an equal eval in this kind of position. but wouldn't it be better then to return something like +- 1 so that you never blunder into this when you are e.g. a piece up and see this type of transition? i generally try to return huge evals only when i am very certain that they are correct. cheers martin >I have considered trying to do a really good KP eval; at the moment it is on the >back-burner but I might return to it someday. > >anthony
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