Author: John Hatcher
Date: 13:22:07 03/16/01
Go up one level in this thread
On March 16, 2001 at 16:09:53, Dann Corbit wrote: >On March 16, 2001 at 16:02:20, John Hatcher wrote: > >>Here is a position arising from Rueben Fine's "Basic Chess Endings", No. 309b - >> >>[D]r7/4P1k1/3K4/8/8/8/8/5R2 w >> >>White wins after 1. Ra1. This solution was found instantly (of course) by both >>Wcrafty-18.6 (using Winboard) and Fritz6, both using the same 5-piece Nalimov >>tablebases. >> >>But now it gets strange. What if White temporizes first with 1. Rg1+ Kf7, >>arising at this position: >> >>[D]r7/4Pk2/3K4/8/8/8/8/6R1 w >> >>Wcrafty-18.6 instantly finds the win after 2. Rf1+ Kg7 (not 2. ...Ke8? 3. Rf8#) >>3. Ra1, transposing into the first position. However, Fritz6 doesn't see the >>win!? It's engine output reads: >> >>Analysis by Fritz 6: >> >>1. = (0.03): 10.e8R Rxe8 11.Rf1+ Kg6 12.Kd5 Kg5 13.Rf7 Rd8+ 14.Ke5 Re8+ >>2. = (0.00): 10.Re1 >>3. = (0.00): 10.Rh1 >>4. = (0.00): 10.Rd1 >>5. = (0.00): 10.Ke5 >>6. = (0.00): 10.Kd5 >> >>How can Fritz6 see the win in the first position and not see it in the second? >>The most obvious move, 2. Rf1+, isn't even listed in the engine output!? >> >>What's going on here? Can anyone duplicate this strange output? > >That is very odd. Every engine I tested (which knows about tablebase files) >found it immediately. > >I have the 5 men files. Maybe Fritz has only the 4 men files available? No, Fritz6 and Wcrafty-18.6 are accessing the same 5-piece tablebase files. Just to be certain, I run the native Chessbase version of Crafty-18.03 under Fritz6 and it instantly found the win in the second position after 2. Rf1+. Fritz6 accesses and uses the 5-piece tablebases just fine, as evidenced by the fact that it instantly found the win (1. Ra1) in the first position. I've been using the 5-piece tablebases under Fritz for a while, and they've always worked just fine. Even stranger, in the first position, Fritz announces mate in 'x' moves if White plays 1. Rg1+ instead of 1. Ra1, but then "loses" the mate when it reaches the second position. I'm stumped. JOHN
This page took 0 seconds to execute
Last modified: Thu, 15 Apr 21 08:11:13 -0700
Current Computer Chess Club Forums at Talkchess. This site by Sean Mintz.