Author: Heiner Marxen
Date: 19:27:36 01/17/01
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On January 17, 2001 at 19:41:34, leonid wrote: >On January 17, 2001 at 18:43:43, Paul wrote: > >>On January 17, 2001 at 18:18:34, leonid wrote: >> >>>On January 17, 2001 at 18:10:38, Paul wrote: >>>> >>>>My program says mate in 9 for black ... here's a line: >>>> >>>>1... Qxb4 2. Rg8+ Ne8 3. Nxe4 Ncxb3+ 4. cxb3 Nxb3+ 5. axb3 Qxa3+ >>>>6. bxa3 Qcc3+ 7. Nxc3 Qxc3+ 8. Ka2 Rd2+ 9. Bc2 Qexb3x >>>> >>>>Paul >>> >>>Can you indicate by what program you solved and all basic data about solution? >>>Selective or brute force search, hash table, special mate solver or usual chess >>>game. Speed of your computer. >>> >>>Thanks, >>>Leonid. >> >>Hi Leonid ... >> >>It's my own program 'Pretz', selective nullmove search, 48MB hash, usual >>chess program, 400MHz PII. So it's possible there's a shorter mate. >> >>Don't know the exact solving time, cause I had more things running >>at the same time, but it was a couple of minutes. >> >>Paul > >Thanks! > >Pretty new for me to see that nullmove could be used as some kind of selective >search for mate. > >It is possible that 9 moves is the shortest move. I only found that mate is >between 11 moves and 7. Six moves I looked through brute force. In six mate not >existe. > >Brute force, even 6 moves took on mine around 6 minutes. Branching factor looked >very bad for this position. With similar branching factor and having no hash in >the program, I thought that looking for exact solution will be too long. Chest says there is no mate in 7. 214 seconds K7/600 with 20 MB hash table. Since I have already running a long job, it will take some time to complete depth=8. Heiner >Please indicate address of your program, if it is complet chess program (not >engin) and if it free. Curious to see if I already know it. > >Thanks, >Leonid.
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