Author: Andrew Williams
Date: 12:42:45 05/29/01
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On May 29, 2001 at 15:04:54, Peter Fendrich wrote: >On May 29, 2001 at 14:42:43, Miguel A. Ballicora 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 >> >>Mobility helps a little in this respect. My program Gaviota has an small >>evaluation where the mobility component is a big % of it. I gives in this >>position +1.75 for white. > >I try to minimise the mobility factor and find other terms in order to achieve >about the same effect. In many positions a heavy weight on mobility will give >strange play for Terra. But herre it would help. >One problem here is the K-positions. Terra gives a lot of punishment for the >white K position that doesn't have any pawn shelter. In an open position that >would be ok but here it is not. >//Peter You're right. This is a nasty position. PM scores it statically as +0.21 for Black, which is obviously not helpful. It has the same problem as Terra, insofar as it thinks that White's King is in more danger than Black's. Part of the problem is that it's difficult for PM's dynamic king safety factors to kick in. All it can see is that White's King has less pawn shelter than Black's. How many plies from this position does it take for Terra to see that Black is in serious trouble? Mine sees White at +1.5 at depth nine, but that takes 2 seconds even on my Athlon 1200. Andrew
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