Author: Bob Durrett
Date: 08:12:57 02/24/04
Go up one level in this thread
On February 24, 2004 at 11:06:00, Robert Hyatt wrote: >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... Why not get rid of bugs when you know about them? Bob D. > > >> >>>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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