Author: Slater Wold
Date: 20:16:54 03/06/02
Go up one level in this thread
On March 06, 2002 at 23:13:43, Jeremiah Penery wrote: >On March 06, 2002 at 22:49:38, Slater Wold wrote: > >>On March 06, 2002 at 22:27:17, Uri Blass wrote: >> >>>On March 06, 2002 at 19:18:16, Slater Wold wrote: >>> >>>>I am 100% sure TB's do indeed take castling into consideration. >>> >>> >>>No >>>You do not understand how tablebases work. >>>There are no moves in tablebases. >>> >>>The engine generates all the legal moves and looks in the tablebases after these >>>moves to see distance to mate. >> >> >>Um, well, according to Hyatt, it would tell the TB "o-o" and it wouldn't return >>anything. I am very well aware how TB's work. > >No, that's not how they work. The engine would feed it the position after the >move O-O was made, and the TB would return MATE in 2. But if you give the >position 2 plies before the castling, the TB will return MATE in 4, because it >didn't calculate the distance to mate with castling rights in consideration. If >you feed Crafty the position where castling is possible, it will return the >correct Mate in 2 score, from tablebases. > >White(1): new >White(1): 8/8/8/8/8/6P1/6k1/4KR1R w K - >White(1): analyze >Analyze Mode: type "exit" to terminate. >end-game phase > clearing hash tables > time surplus 0.00 time limit 30.00 (3:30) > nss depth time score variation (1) > 1 0.00 21.61 1. g4 > 1-> 0.00 21.61 1. g43 > 2 0.00 21.31 1. g4 Kg3 > 2-> 0.00 21.31 1. g4 Kg3 > 3 0.00 ++ 1. g4!! > 3 0.00 21.84 1. g4 Kg3 2. g5 > 3 0.04 Mat06 1. Rf2+ Kxh1 <HT> > 3 0.04 Mat05 1. Rh2+ Kxh2 <HT> > 3 0.04 Mat04 1. Rh8 Kxg3 <HT> > 3-> 0.04 Mat04 1. Rh8 Kxg3 <HT> > <snip> > endgame tablebase-> probes done=277 successful=153 >analyze.White(1): Rf4 >White(1): Rf4 > clearing hash tables > time surplus 0.00 time limit 30.00 (3:30) [easy move] > nss depth time score variation (1) > 1 0.00 12.45 1. ... Kxg3 > 1-> 0.00 12.45 1. ... Kxg3 > 2 0.00 -- 1. ... Kxg3 > 2 0.00 Mat03 1. ... Kxg3 <HT> > 2-> 0.00 Mat03 1. ... Kxg3 <HT> > 3 0.00 Mat03 1. ... Kxg3 <HT> > 3-> 0.00 Mat03 1. ... Kxg3 <HT> > <SNIP> > endgame tablebase-> probes done=2 successful=2 >analyze.Black(1): Kxg3 >Black(1): Kxg3 > clearing hash tables > time surplus 0.00 time limit 30.00 (3:30) > nss depth time score variation (1) > 1 0.00 12.45 2. O-O > 1-> 0.00 12.45 2. O-O4 > 2 0.00 ++ 2. O-O!! > 2 0.00 Mat02 2. O-O <HT> > 2-> 0.00 Mat02 2. O-O <HT> > 3 0.00 Mat02 2. O-O <HT> > 3-> 0.00 Mat02 2. O-O <HT> > 4 0.00 Mat02 2. O-O <HT> > 4-> 0.00 Mat02 2. O-O <HT> > time=0.04 cpu=0% mat=10 n=19 fh=100% nps=10k > ext-> chk=0 cap=0 pp=0 1rep=0 mate=0 > predicted=0 nodes=19 evals=0 > endgame tablebase-> probes done=3 successful=3 > hashing-> trans/ref=82% pawn=0% used=0% >analyze.White(2): > > >>>If castling is legal then the engine looks at the tablebases to see the distance >>>to mate after castling in order to see the mate in 2 score. >> >> >>According to Hyatt, no it doesn't. > >Uri was right, and that's exactly what they do. It's just that they don't take >castling rights into consideration in the mate scores they return. If castling >is possible at the root, the engine will generate that move and feed the >resulting position to the TB, which will return the now-correct mate score. Crafty is actually putting out an eval though. No other engine I have does. It just returns in 0.00 the TB results. Crafty took .5 seconds to find the correct move, while say Shredder, finds it in 0.00 with a 100% TB return. There is _zero_ evaluation from the engine. >>The correct position is: >> >>[D]8/8/8/8/8/6P1/6k1/4KR1R w K -
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