Author: Amir Ban
Date: 07:23:54 01/15/98
Go up one level in this thread
On January 15, 1998 at 09:52:09, Robert Hyatt wrote: >On January 15, 1998 at 09:49:04, Robert Hyatt wrote: > >>On January 15, 1998 at 09:19:45, Robert Hyatt wrote: >> >>>On January 15, 1998 at 08:53:27, Amir Ban wrote: >>> >>>>On January 15, 1998 at 08:01:10, Robert Hyatt wrote: >>>> >>>>>On January 15, 1998 at 05:35:18, Amir Ban wrote: >>>>> >>>>>> >>>>>>Maybe we can break the problem into two easier parts: >>>>>> >>>>>>- Who sees a plus score for Qxb3 ? >>>>>>- Who sees a draw score for only shuffling the queen ? >>>>>> >>>>>>Amir >>>>> >>>>> >>>>>I disagree. I have seen Cray Blitz and Crafty win many such positions. >>>>>It >>>>>takes a lot of time, but being ahead +12 is *not* going to draw if the >>>>>program >>>>>understands the 50 move rule and repetitions. IE sooner or later it is >>>>>going >>>>>to see that another couple of queen moves draws. And it is going to >>>>>then >>>>>search for a way to push a pawn, or capture something. Being ahead +12 >>>>>is >>>>>enough to allow the queen sac and still remain far enough ahead in >>>>>material >>>>>to win. >>>>> >>>>>In 1986 we had a game somewhat like this at the WCCC in Germany. Except >>>>>we were only up 1.5 pawns or saw. After about 30-35 moves of shuffling, >>>>>Cray Blitz found what we already knew... it had to give up its pawn, but >>>>>then could win. It did, but only when urged on by the threat of a draw. >>>>>I think many programs would win this, assuming the game is played for >>>>>another 45 moves. +12 is simply not going to draw. Now if we are into >>>>>"elegant" wins, and if this has to be solved *now* or never, then we >>>>>have >>>>>a problem. But I've never seen a +12 position that wasn't winnable, >>>>>except for a few that are close like Q vs bp... >>>> >>>> >>>>Very well. So how about this discount: Set the 50-move counter to >>>>something close to 50 and find the winning PV. >>>> >>>>Amir >>> >>> >>>this I'll run... results soon... >> >> >>Heres the results run on Cray Blitz (Crafty's machine seems to stay busy >>playing ICC games...) >> >>I set the 50 move counter to 6 plies away from draw. I snipped a lot of >>noise around the point where it started seeing draw, as it was changing >>it's mind, then failing high, then failing low, etc. I stopped after 10 >>seconds as it seemed to be "on track". I want to try this on Crafty >>later, >>as I'm not sure the two connected passed pawns are valuable enough to >>make >>it want to do this, period, unless the search can go deep enough to see >>them >>advancing. CB is a little more aggressive on evaluating connected >>passers, >>because it searches so deeply... >> >> >> depth time score variation (1) >> 1 0:00 7.441 Qg2 >> 1-> 0:00 7.441 Qg2 >> 2 0:00 7.364 Qg2 Bc6 >> 2-> 0:00 7.364 Qg2 Bc6 >> 3 0:00 7.364 Qg2 Bc6 Qg3 >> 3-> 0:00 7.364 Qg2 Bc6 Qg3 >> 4 0:00 7.336 Qg2 Bc6 Qg3 Kb6 >> 4-> 0:00 7.336 Qg2 Bc6 Qg3 Kb6 >> >><noise deleted> >> >> 8 0:00 -- Qf1 >> 8 0:00 0.000 Qf1 Bc6 Qg2 Ba4 >> 8 0:00 0.234 Qd1 Bc6 Qxb3 cxb3 Kxb3 Kb6 c4 Kc5 >> 8-> 0:00 0.234 Qd1 Bc6 Qxb3 cxb3 Kxb3 Kb6 c4 Kc5 >> 9 0:00 0.234 Qd1 Bc6 Qxb3 cxb3 Kxb3 Kb6 c4 Kc5 >>Kc3 >> 9-> 0:00 0.234 Qd1 Bc6 Qxb3 cxb3 Kxb3 Kb6 c4 Kc5 >>Kc3 >> 10 0:00 0.302 Qd1 Bc6 Qxb3 cxb3 Kxb3 Kb6 c4 Kc5 >>Kc3 >> Bd7 >> 10-> 0:00 0.302 Qd1 Bc6 Qxb3 cxb3 Kxb3 Kb6 c4 Kc5 >>Kc3 >> Bd7 >> 11 0:00 0.388 Qd1 Be8 Qxb3 cxb3 Kxb3 Kb6 Kc4 Bf7+ >> Kd4 Kb5 b4 Bc4 >> 11-> 0:00 0.388 Qd1 Be8 Qxb3 cxb3 Kxb3 Kb6 Kc4 Bf7+ >> Kd4 Kb5 b4 Bc4 >> 12 0:00 0.388 Qd1 Be8 Qxb3 cxb3 Kxb3 Kb6 Kc4 Bf7+ >> Kd4 Kb5 b4 Bc4 Ke5 >> 12-> 0:00 0.388 Qd1 Be8 Qxb3 cxb3 Kxb3 Kb6 Kc4 Bf7+ >> Kd4 Kb5 b4 Bc4 Ke5 >> 13 0:00 0.293 Qd1 Be8 Qxb3 cxb3 Kxb3 Ba4+ Ka3 Bd1 >> c4 Kb6 b4 Kc6 c5 Bf3 >> 13-> 0:00 0.293 Qd1 Be8 Qxb3 cxb3 Kxb3 Ba4+ Ka3 Bd1 >> c4 Kb6 b4 Kc6 c5 Bf3 >> 14 0:00 0.293 Qd1 Be8 Qxb3 cxb3 Kxb3 Ba4+ Ka3 Bd1 >> c4 Kb6 b4 Kc6 Kb2 Bf3 c5 >> 14-> 0:00 0.293 Qd1 Be8 Qxb3 cxb3 Kxb3 Ba4+ Ka3 Bd1 >> c4 Kb6 b4 Kc6 Kb2 Bf3 c5 >> 15 0:00 0.269 Qd1 Be8 Qxb3 cxb3 Kxb3 Ba4+ Ka3 Bd1 >> c4 Ka6 b4 Kb6 Kb2 Bf3 c5+ Kc6 Kb3 >> 15-> 0:01 0.269 Qd1 Be8 Qxb3 cxb3 Kxb3 Ba4+ Ka3 Bd1 >> c4 Ka6 b4 Kb6 Kb2 Bf3 c5+ Kc6 Kb3 >> >> >>So it isn't hopeless, but needs some help from the 50 move rule. This >>was >>run on a 1 processor C90. I suspect the 32 processor T90 could reach 20 >>plies in 1 second, and that this could be searched to a depth of 30 or >>so, >>with no trouble. In that case, I'm sure the scores would be much higher >>as >>by then the pawns would be well on their way... > > >one other thing. If you'd like to see your favorite program solve this, >you need to (a) play to near 50 moves and (b) set the draw score >(contempt >factor) low enough that it will think drawing is worse than giving up >the >Q. Crafty would probably score this about -.5 I suspect, although I >will >give its analysis later on. Setting the contempt to -1.00 would >probably >be more than enough to find this at 10 seconds, but I'm not sure. The >deeper you can search, the more likely the sac looks good as the pawns >can >slowly advance, until the bishop gets sacrificed to stop them... > >Interesting position of course... Hey, not fair ! You have the 50-move rule discount, not license to play around with the eval through the contempt factor. Evaluating the two passed pawns as worth the bishop would be wrong here. With so many other pawns and the black king positioned well black should in general win easily. This position is very unusual in that the white pawns are safe from attack while black's h7 cannot be protected. Amir
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