Author: James Robertson
Date: 16:56:10 10/31/98
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On October 31, 1998 at 16:45:01, Inmann Werner wrote: >I have problems with "nearly mate" positions, where the opponent can do some >checks, so the mate gets beyond the horizon. > >One Example (really interesting!) > > >Position (LCTII CMB 01) > xrxxxxkx > xqxxbpxx > xxxpxxpx > xxpPxxxx > PxNxxxxR > xxPxxQPx > xPxxxPKx > xxxxxxxx > >Best: c4d6/e7d6/f3f6 white wins > >In depth 7 , my program should find the solution, but it does not! The problem >is, that black can make checks to bring the mate beyond the horizon. At each >check, I extend the search for 1 ply, but it is not enough. > >The computer thinks: >C4d6/e7d6/f3f6/b7d5+/g2h2/d6g3+!!/h2g3/d5d3+/g3h2/g8f8/ no h4h8 and black >"stands good" >7 plys plus 3 plys the checks end up at 10!! > >This things really often happen, and I am reall unhappy with it. When I tried to >extend at a check with 2 plys, this problem was solved very early. But the >overall searchdepth goes dramatically down, so the program plays worse. >On an attack, it is nearly always possible for the opponent to slow down the >attack with "senseless", but forced moves. >I thought about something like: >This is a mate in 1, therefore don´t let you disturb with "senseless " moves. >But I have no thought, how to implement such a thing. >Suggestions? > >Werner I think Mr. Hyatt is right... there is nothing to do about it except search deeper. Think about it this way: in a combination that forces a win, ANYTHING the opponent does is "senseless"; it doesn't stop the combination, but merely delays the inevitable result, and yet we think of it as part of the combination. I suppose that same thought can apply to this position. :) James P.S. Crafty took till ply 10 to find the win.
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