Author: J. Wesley Cleveland
Date: 16:16:31 05/29/01
Go up one level in this thread
On May 29, 2001 at 16:47:19, Andrew Williams wrote: >On May 29, 2001 at 16:26:38, Peter Fendrich wrote: > >>On May 29, 2001 at 15:42:45, Andrew Williams wrote: >> >>>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 >> >>Terra needs depth=11 to really find that. Between 9 and 11 he is slowly changing >>his mind. On my PII 300 MHz it takes more than 2 minutes to get it: >>Depth Time Eval Nodes >>----- ---- ----- ------- >>11 2:24 248 8730379 Rxh7 Kxh7 Rh2 Kg8 Qh3 Bxf6 exf6 Kf8 Qh8 Qg8 f7 >> Kxf7 Rh7 Qxh7 Qxh7 Kf6 >>//Peter > >This is my program's output: > > 8= 62 1 124113 1. Rh6 Rc7 2. Rfh2 Qe8 3. Bf4 > 9> 62 1 144075 1. Rh6 Rc7 2. Rfh2 Qe8 3. Bf4 Rf7 4. Qh3 > 9= 156 3 435349 1. Rh6 Rc7 2. Rfh2 Qe8 3. Qh3 Qf7 4. Rxg6 Qxg6 > 5. Rg2 Qxg2 6. Kxg2 >10> 156 3 488379 1. Rh6 Rc7 2. Rfh2 Qe8 3. Qh3 Qf7 4. Rxg6 Qxg6 > 5. Rg2 Qxg2 6. Qxg2 Kf8 7. Bf4 >10b 165 6 855439 1. Rh3 Rc7 2. Rfh2 Qe8 3. Qg5 b4 4. axb4 >10= 169 6 875504 1. Rh3 Rc7 2. Rfh2 Qe8 3. Qg5 b4 4. axb4 >11> 169 8 1137228 1. Rh3 Rc7 2. Rfh2 Qe8 3. Qg5 b4 4. axb4 >11b 224 12 1771335 1. Rxh7 Kxh7 2. Rh2 Kg8 3. Qh3 Bxf6 4. exf6 >11= 285 18 2828059 1. Rxh7 Kxh7 2. Rh2 Kg8 3. Qh3 Bxf6 4. exf6 Kf8 > 5. Qh8 Qg8 6. f7 Kxf7 7. Rh7 Qxh7 8. Qxh7 Kf6 >12> 285 18 2905936 1. Rxh7 Kxh7 2. Rh2 Kg8 3. Qh3 Bxf6 4. exf6 Kf8 > 5. Qh8 Qg8 6. f7 Kxf7 7. Rh7 Qxh7 8. Qxh7 Kf6 >12= 295 23 3794754 1. Rxh7 Kxh7 2. Rh2 Kg8 3. Qh3 Bxf6 4. exf6 Kf8 > 5. Qh8 Qg8 6. f7 Kxf7 7. Rh7 Qxh7 8. Qxh7 Kf6 9. Kf2 > > >PM also takes until depth 11 to see this one. > >Andrew Crafty finds Rxh7 at ply 8 and 1.65 secs at 300000 nps.
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