Author: Mridul Muralidharan
Date: 08:09:32 12/15/05
Go up one level in this thread
Nice ! Now I know one of the reasons why Baron is so strong in endgames :) Mridul On December 15, 2005 at 10:34:40, Richard Pijl wrote: > >>Of course the knight can win a move but you still may detect unstoppable pawn if >>the knight need to win 2 moves to stop the pawn or cases that the knight cannot >>win a move thanks to calculation of the distance to the opponent king. > >These cases are very very rare, especially in practical play. > >> Besides, in most cases the >>>'stopping' capability of the knight is more restricted by pawn and king >>>positions than anything else anyway. >> >>Of course it is clear that distance function cannot detect all the cases >>when pawns are unstoppable but only part of the cases. >> >> finally, you should also consider >>>alternative stopping fields like the second rank, as sometimes it is possible to >>>reach a stopping field other than the promotion square. >> >>of course but I do not think that checking distance to some squares is >>expensive. > >Checking just distance is not expensive. But taking pawn and king positions into >account is, as you cannot fully precompute it. > >>I do nothing about it and I did not see Movei lose many games because of not >>detecting unstoppable passed pawns. > >I don't think it is very important either, at least when you consider total >playing strength. >However, when you reach a knight ending, knight-deflection is a very important >pattern. I think this type of knowledge will help in finding knight deflection >type of combinations faster. > >>I suspect that the main advantage is simply being able to prune lines and search > >pruning based on this alone is dangerous, as you can never really be sure that >this is 100% right. You'll need search to be able to correct the evaluation when >it goes wrong. > >>faster but the advantage is limited and middle game evaluation is more >>important. > >of course. > >>Rybka that is probably the best program does not detect it by evaluation as the >>following analysis prove(it shows a score of +12 inspite of the fact that even >>without seeing that black promote with check black queen first) >> >>Note that Movei has big problem in this type of positions today and it's search >>is very unstable and it needs depth 10 to see that white is losing. >> >>[D]k6N/8/8/p7/8/6PP/8/7K w - - 0 1 > >The Baron has -1.02 in evaluation here, without search. >> >>Analysis by Rybka 1.0 Beta 32-bit: >> >>1.Nf7 >> +- (12.21) Depth: 3 00:00:00 >> >>Another position when Movei is better in finding black's win but rybka is slower >>in finding score above draw. >> >>[D]k6N/8/8/p7/8/6PP/r6R/7K b - - 0 1 > >Due to the rooks, Baron's static evaluation gives a score of -4.91 (advantage >for white). In search, the first reported line shows the win for black though: > ply time nodes score pv > 10(17)& 0:00.22 111865 +3.50 Ra2xh2 Kh1xh2 a5-a4 g3-g4 a4-a3 > Nh8-g6 a3-a2 h3-h4 a2-a1Q h4-h5 Qa1-e1 > Kh2-h3 Qe1-h1 Kh3-g3 (Ka8-b7) (Kg3-f4) >After forcing Rxh2, Kxh2, the static evaluation is already 0.92, advantage for >black, so just a qsearch should be enough for the Baron to show a black >advantage. >> >>Analysis by Rybka 1.0 Beta 32-bit: >> >>1...Ra1+ >> = (0.00) Depth: 3 00:00:00 >>1...Ra1+ 2.Kg2 Ra2+ 3.Kg1 >> = (0.00) Depth: 4 00:00:00 >>1...Ra1+ 2.Kg2 Ra2+ 3.Kg1 Ra1+ 4.Kf2 >> = (0.00) Depth: 5 00:00:00 >>1...Ra1+ 2.Kg2 Ra2+ 3.Kg1 Ra1+ 4.Kf2 Ra2+ 5.Kg1 Ra1+ 6.Kf2 >> = (0.00) Depth: 6 00:00:00 >>1...Ra1+ 2.Kg2 Ra2+ 3.Kg1 Ra1+ 4.Kf2 Ra2+ 5.Kg1 Ra1+ 6.Kf2 >> = (0.00) Depth: 7 00:00:00 >>1...Ra1+ 2.Kg2 Ra2+ 3.Kg1 Ra1+ 4.Kf2 Ra2+ 5.Kg1 Ra1+ 6.Kf2 >> = (0.00) Depth: 8 00:00:00 1kN >>1...Ra1+ 2.Kg2 Ra2+ 3.Kg1 Ra1+ 4.Kf2 Ra2+ 5.Kg1 Ra1+ 6.Kf2 >> = (0.00) Depth: 9 00:00:00 1kN >>1...Ra1+ 2.Kg2 Ra2+ 3.Kg1 Ra1+ 4.Kf2 Ra2+ 5.Kg1 Ra1+ 6.Kf2 >> = (0.00) Depth: 10 00:00:00 2kN >>1...Ra1+ 2.Kg2 Ra2+ 3.Kg1 Ra1+ 4.Kf2 Ra2+ 5.Kg1 Ra1+ 6.Kf2 >> = (0.00) Depth: 11 00:00:00 3kN >>1...Ra1+ 2.Kg2 Ra2+ 3.Kg1 Ra1+ 4.Kf2 Ra2+ 5.Kg1 Ra1+ 6.Kf2 >> = (0.00) Depth: 12 00:00:00 5kN >>1...Rxh2+ 2.Kxh2 a4 3.Nf7 a3 4.Ne5 a2 5.Nc4 a1Q 6.Ne3 >> -+ (-5.28) Depth: 12 00:00:00 39kN >>1...Rxh2+ 2.Kxh2 a4 3.Nf7 a3 4.Ne5 a2 5.Nc4 a1Q 6.Ne3 >> -+ (-5.28) Depth: 13 00:00:01 46kN >>1...Rxh2+ 2.Kxh2 a4 3.Nf7 a3 4.Ne5 a2 5.Nc4 a1Q 6.Ne3 >> -+ (-5.28) Depth: 14 00:00:01 56kN >>1...Rxh2+ 2.Kxh2 a4 3.Nf7 a3 4.Ne5 a2 5.Nc4 a1Q 6.Ne3 >> -+ (-5.28) Depth: 15 00:00:02 71kN >>1...Rxh2+ 2.Kxh2 a4 3.Nf7 a3 4.Ne5 a2 5.Nc4 a1Q 6.Ne3 >> -+ (-5.28) Depth: 16 00:00:02 90kN >> >>(, 15.12.2005) >> >>Uri
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