Author: Tony Werten
Date: 03:37:15 02/03/01
Go up one level in this thread
On February 03, 2001 at 05:55:48, Enrique Irazoqui wrote: >On February 02, 2001 at 19:52:28, Tony Werten wrote: > >>On February 02, 2001 at 19:24:40, Enrique Irazoqui wrote: >> >>>On February 02, 2001 at 19:08:38, Tony Werten wrote: >>> >>>>On February 02, 2001 at 12:10:58, James T. Walker wrote: >>>> >>>>>On February 02, 2001 at 03:19:14, Timothy J. Frohlick wrote: >>>>> >>>>>>On February 02, 2001 at 01:28:59, Jouni Uski wrote: >>>>>> >>>>>>>[D]8/6kn/3B3p/5K1B/8/8/8/8 b - - >>>>>>> >>>>>>>resign 1-0! Why? Is this really white's win? >>>>>>> >>>>>>>JouniDate: 1/2/2001 >>>>>> >>>>>>Jouni, >>>>>> >>>>>>Gambit Tiger without tablebases solves this as a mate in 46 in 26 minutes on a >>>>>>PII 333 with 48 Megs Hash. >>>>>> >>>>>>1... Ng5 2. Bc5 Nf7 3. Bd4+ Kf8 4. Kf6 Ng5 5. Bc5+ Kg8 6. Kf5 Nf7 7. Be7 Ng5 8. >>>>>>Bb4 Nf7 9. Kg6 Ne5+ 10. Kf6 Nd7+ 11. Ke7 Ne5 12. Bc3 Nc6+ 13. Ke8 Kh7 14. Kf7 >>>>>>Ne5+ 15. Kf6 Nc6 16. Bf3 Nd8 17. Bb4 h5 18. Be4+ Kh8 19. Be7 Nc6 20. Bxc6 Kh7 >>>>>>21. Be4+ Kg8 22. Kg6 Kh8 23. Bd5 h4 24. Bf6# >>>>>> >>>>>> >>>>>>1-0 >>>>>> >>>>>>Maybe tablebases are not all that great after all. They don't always find the >>>>>>shortest solution to a problem. >>>>>> >>>>>>Tim Frohlick >>>>> >>>>>Why mate in 46 and then you give a mate in 24 line? I believe the "mate in 46" >>>>>is true as Shredder 5 finds a mate in 47 (maybe a difference in terms) but where >>>>>did the above line which is 24 moves come from? >>>> >>>>Normally a move consists of 2 ply, but in this case the first and the last move >>>>are only 1 ply. So effectively 23 moves => 46 ply. >>>> >>>>47 ply is impossible since black starts and white finishes so it has to be even. >>> >>>Not really. In the line posted above, after 24.Bf6# the program must see 1 more >>>ply to realize that the black KIng has no escape, so it's a 47 ply search. >> >>Maybe it's 48 ply because white has to realize that black couldn't play so it >>won :) >> >>Even if your program needs a 100 ply search to realize it was mated, it's stil a >>mate in 46 ply. >> >>>A typical problem "white to play and mate in 6" is 12 ply deep, not 11. >> >>Yes it is ( and besides this is a "black to play and white mates problem" ) >> >>By your definition, white play and mate in 1 is a 2 ply mate. > >A mate in one takes a 2 ply search. The first ply finds the checks, but you need >the second to know if a check is a mate. That's an implementation issue. If you don't do check in qsearch you probabely need a 2 ply search. In my program I need 1 ply. But that doesn't matter. It's a 1 ply mate and the score should reflect a 1 ply mate, not 2. Tony > >Enrique > >>Tony >> >>> >>>Enrique >>> >>>>Tony >>>> >>>>>Jim
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