Author: Inmann Werner
Date: 10:03:07 11/01/98
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On October 31, 1998 at 19:53:46, Andrew Dados wrote: > >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 > > One solution I find acceptable is whenever you make null move generate all >checks at next ply even if null throws you to quiescence... that way null >returns 'being mated' score - and based on that you can extend your search >deeper...hopefully going beyond all delaying moves. > >Andrew I also thought about using the null move for this problems. Now my program finds the move at ply eight. I do not agree, that "brute force and fast" going into deeper plys is always better. If you make some "nice things", maybe the program finds something one ply earlier, which means "speed increasing" by factor three. So its worth to think about it, but always calculate the costs. I will try something with null moves and extensions, lets look what comes out. Werner
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