Author: Robert Hyatt
Date: 17:45:08 05/29/01
Go up one level in this thread
On May 29, 2001 at 18:41:44, Peter Fendrich wrote: >On May 29, 2001 at 17:19:09, Robert Hyatt wrote: > >>On May 29, 2001 at 14:21:13, Peter Fendrich wrote: >> >>>This position appeared in an ICC game: Guitje - TerraPi >>> >>>[D]2r3kb/5q1p/4pPp1/1p1pP3/p2P2Q1/PrP5/1P3R1R/2B3K1 w - - 0 42 >>> >>>the last move from Terra was 41... b5 >>>Some moves earlier when white made g6, Terra decided to move the bishop from g7 >>>to h8. >>>Both Rb3 and Bh8 are locked in and Terra is absolutely unaware of the >>>hopeless situation. Yes, Terra lost... >>> >>>I see two different but connected problems for computer programs here: >>> - the closed position itself >>> - the two blocked pieces. >>> >>>How do you solve/avoid positions like this? Terra has about equal eval for this >>>position. >>>It is of course possible to punish pawn chains like this in order to avoid >>>closed positions but is that really a solution and how to deal with blocked >>>positions? >>> >>>//Peter >> >> >>First, this looks dead lost. I get big scores (>3) after a few seconds and 13 >>plies. > >Yes it is but the point is that a search is needed and the search finds a >tactical breaktrhrough but that's another story. The problem is the total >unawareness of the situation up til now and the willingness to end up in a >position like this. The fact remains that Terra gives a completely wrong static >evaluation. How about Crafty? Here is my static evaluation: note: scores are for the white side material evaluation................. 0.00 development......................... 0.00 pawn evaluation..................... 1.45 passed pawn evaluation.............. -0.45 passed pawn race evaluation......... 0.00 king safety evaluation.............. 0.48 interactive piece evaluation........ -0.45 total evaluation.................... 1.03 It concludes white is a pawn up, based only on evaluation of positional things, since material is 0.00 > >> >>The position you gave is too late to repair. You have to recognize blocked >>pawns _before_ they are blocked, which means the 'mistakes' were made earlier >>in the game. I evaluate blocked pawns in Crafty, but I also evaluate pawn >>levers and make sure I keep a pawn break opportunity alive to avoid getting >>into totally closed positions... > >I don't like the idea to give punishment for things that theoretical aren't bad. >A closed position can be a winning position even for a computer, if we could >handle it.... > Not exactly. If it is _really_ closed to the computer, you have no way of winning at all since you have no pawn breaks. It means that either your opponent makes a break that wins for him, or he makes a mistake and makes a break that lets you win. But if you have _no_ break options, you are stuck with what he wants. That is the point of my pawn lever evaluation code... to not reach positions where I have zero pawn breaks, since I don't want to be at my opponent's mercy... >> >>Here you should probably find Rxh7 is crushing of course... > >//Peter
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