Author: Robert Hyatt
Date: 08:06:00 02/24/04
Go up one level in this thread
On February 24, 2004 at 10:37:21, martin fierz wrote: >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 You are looking at this the wrong way. If you want 100% accuracy, you will die from it. :) If you don't do what I do, you will like connected passers, and in 90% of the games I will beat you when that comes up. Do you want to be right 100% of the cases you recognize, leaving 95% as "unclear and probably lost" or do you want to be right in 90% of the total cases? I choose the latter... No doubt it can be made more accurate. But no doubt that without it, it is even less accurate... > >>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
This page took 0.02 seconds to execute
Last modified: Thu, 15 Apr 21 08:11:13 -0700
Current Computer Chess Club Forums at Talkchess. This site by Sean Mintz.