Author: John Hatcher
Date: 13:02:20 03/16/01
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? JOHN
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