Author: Robert Hyatt
Date: 22:06:33 06/25/98
Go up one level in this thread
On June 26, 1998 at 00:22:31, Bruce Moreland wrote: > >On June 25, 1998 at 23:19:32, Robert Hyatt wrote: > >>On June 25, 1998 at 21:45:15, Robert Hyatt wrote: >> >>>On June 25, 1998 at 19:25:39, Bruce Moreland wrote: >>> >>>> >>>>On June 25, 1998 at 16:18:29, Robert Hyatt wrote: >>>> >>>>>Bruce is doing some extension stuff that might well pick this up quickly, >>>>>as Cray Blitz gets this right at 5 plies and 0 seconds, but the PV is quite >>>>>long and has the horizon moves by white correct, and it realizes that black >>>>>*has* to stop to capture each pawn that is offered, but it discovers that >>>>>those moves are "singular" and it extends them quite deeply. I'm not yet >>>>>doing singular extensions in crafty, so I don't catch this so quickly, but >>>>>I'm starting to play with them again to see if I like the result. >>>> >>>>Nope, nothing weird here, just null move with maybe some conservative and >>>>minimal pawn push extensions and some razoring. >>>> >>>>I find it in 9 plies, but it's +2 until 14 plies, at which point it goes up to >>>>+5. >>>> >>>>If this contradicts anything in my original post on this, it's because I've >>>>changed versions and machines (trivial version changes). >>>> >>>>bruce >>> >>> >>>can you post your 9 ply PV? the problem I have at 9 plies is that white has >>>a few threats of his own. Starting with h4 and black has to retake... then >>>another pawn push that black has to take time out for. Without those, this is >>>an easy position, but each white pawn push requires a capture by black or white >>>gets a queen first. This is what hurts my search... >> >> >> >>this is an interesting position. I just ran some analysis. First, here >>is my 9 ply search: >> 9-> 0.25 -0.03 1. ... Ra3 2. Rxa3 bxa3 3. g4 Kd5 4. >> g5 Kd6 5. h5 gxh5 6. Kh4 >> >> >>this is cute. Ra3 Rxa3 bxa3 are forced. g4 is cute as now black has >>to do something besides go after the a-pawn, else g5 and h4 queens first. >>Crafty understands the threatened promotion, so keeps the king in the square >>of the potentially passed h-pawn... >> >>within 9 plies, I obviously can't solve this. >> >>here's additional searches, showing what I see. I don't understand this >>until ply=12: >> >> 10 0.53 -- 1. ... Ra3 >> 10 0.76 -0.51 1. ... Ra3 2. Rxa3 bxa3 3. g4 Kd5 4. >> g5 e5 5. h5 gxh5 6. g6 Ke6 7. g7 >> 10-> 0.77 -0.51 1. ... Ra3 2. Rxa3 bxa3 3. g4 Kd5 4. >> g5 e5 5. h5 gxh5 6. g6 Ke6 7. g7 >> 11 1.12 -0.71 1. ... Ra3 2. Rxa3 bxa3 3. g4 Kd5 4. >> g5 e5 5. h5 gxh5 6. g6 Ke6 7. g7 Kf7 >> 11-> 1.13 -0.71 1. ... Ra3 2. Rxa3 bxa3 3. g4 Kd5 4. >> g5 e5 5. h5 gxh5 6. g6 Ke6 7. g7 Kf7 >> 12 2.44 ++ 1. ... Ra3!! >> 12 4.17 2.46 1. ... Ra3 2. Rxa3 bxa3 3. h5 gxh5 >> 4. Kh4 Kc3 5. Kxh5 Kb2 6. g4 fxg4 7. >> Kh4 Kxa2 8. Kxg4 >> 12-> 4.19 2.46 1. ... Ra3 2. Rxa3 bxa3 3. h5 gxh5 >> 4. Kh4 Kc3 5. Kxh5 Kb2 6. g4 fxg4 7. >> Kh4 Kxa2 8. Kxg4 >> >>big question is, now, how is Ferret seeing this at depth=9, because it >>looks quite tricky for both sides to me. What is Crafty overlooking here? > >PV 00:00:00.592 9 35 [wrong] Ra3 >PV 00:00:00.602 9 107 [wrong] Ra3 >PV 00:00:00.633 9 248 [wrong] Ra3 Rxa3 bxa3 g4 Kc3 Kg3 Kb2 h5 gxh5 gxf5 >PV 00:00:00.756 10 198 [wrong] Ra3 Rxa3 bxa3 g4 Kc3 h5 fxg4+ Kxg4 gxh5+ Kxh5 >Kb2 Kg5 Kxa2 Kf6 Kb1 > >I think it failed low then failed high in ply 10, but I don't know for sure, >this is odd. > >PV 00:00:00.825 11 198 [wrong] Ra3 Rxa3 bxa3 g4 Kc3 h5 fxg4+ Kxg4 gxh5+ Kxh5 >Kb2 Kg5 Kxa2 Kf6 Kb1 Kxe6 >PV 00:00:01.673 12 188 [wrong] Ra3 Rxa3 bxa3 g4 fxg4+ Kxg4 Kc3 Kg5 Kb2 Kxg6 >Kxa2 f5 exf5 Kxf5 Kb2 >PV 00:00:02.336 13 190 [wrong] Ra3 Rxa3 bxa3 g4 fxg4+ Kxg4 Kc3 Kg5 Kb2 Kxg6 >Kxa2 f5 exf5 Kg5 Kb1 Kxf5 >PV 00:00:03.173 14 240 [wrong] Ra3 Rxa3 bxa3 g4 fxg4+ Kxg4 Kc3 Kg5 Kb2 Kxg6 >Kxa2 f5 exf5 Kg5 Kb1 Kxf5 >PV 00:00:04.468 14 515 [wrong] Ra3 Rxa3 bxa3 h5 gxh5 Kh4 Kc3 Kxh5 Kb2 g4 fxg4 >Kg5 Kxa2 Kf6 g3 >PV 00:00:09.230 15 446 [wrong] Ra3 Rxa3 bxa3 h5 gxh5 Kh4 Kc3 Kxh5 Kb2 g4 fxg4 >Kh4 Kb1 f5 exf5 ok... I played out your 9 ply variation... it ends up with black king at b1, black pawn at a3, white king at e6 white pawn at f4, black to move, which looks winnable, but where do you get +2 eval? ie both pawns are unstoppable from a square of the king perspective... in fact, crafty evaluates this as -7, because it realize it promotes soon enough that white is losing. So I won't hit on this position because I consider it already won for black and find something else for white. This is cute... where it seems that black wins, but barely and by walking a very precise tightrope...
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