Author: Russell Reagan
Date: 01:51:30 01/17/04
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On January 16, 2004 at 19:06:21, Harald Faber wrote: > >[D]2r1k1b1/pp4Q1/3p4/q5p1/4P3/1PN2P2/PP6/1K5R b - - 0 1 > >Analysis by Shredder 8: > >1. +- (#153): 33...Lf7 34.Th8+ Ke7 35.Txc8 d5 36.Sxd5+ Kd6 37.Dxf7 De1+ 38.Tc1 >Dc3 39.bxc3 b5 40.Dxa7 Kc6 41.Dc7# >2. +- (#151): 33...Tc7 34.Dxg8+ Kd7 35.Sd5 Tc2 36.Th7+ Kc6 37.Dc8+ Dc7 38.Txc7+ >Kb5 39.Kxc2 a5 40.Dxb7# >3. +- (#7): 33...De5 34.Dxg8+ Kd7 35.Th7+ De7 36.Txe7+ Kxe7 37.Dxc8 Oops...this is easily explainable. It took a minute for me to remember this. It is probably a fail high in a root aspiration search. You know how sometimes you will see a program search like this? 1. +0.25 e4 e5 Nf3 Nf6 2. +0.27 e4 e5 Nf3 Nf6 Bb5 3. ----- d4! <--- This is the line of interest 3. +0.45 d4 d5 c4 e6 The line where there is no score and no PV usually means that a root aspiration search was done and the search failed high. Most programs don't give a PV, or don't give a score, or don't give either. Shredder probably just gives both. The reason is that the fail high in the aspiration search just means that this new move should be better, but you don't have an exact score yet, and you have to re-search with a full alpha-beta window to get the exact score. It is possible that #153 and #151 are the inaccurate scores returned by a fail high aspiration search at the root, and they are resolved to exact scores later.
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