Author: Dann Corbit
Date: 11:10:22 12/27/01
Go up one level in this thread
On December 27, 2001 at 03:51:22, Uri Blass wrote: >I downloaded WAC.epd from Dann corbit's site >in order to test my program and I see that there are some cases >when there is more than one solution and >at least in the first 2 cases the solutions are not correct > > >[D]r1bqk2r/ppp1nppp/4p3/n5N1/2BPp3/P1P5/2P2PPP/R1BQK2R w KQkq - >bm Ba2 Nxf7; id "WAC.022"; > >I am not sure if Nxf7 wins the game >I see that Ba2 is one of the solutions and >I do not understand it >Nxf7 seems clearly better for positional reasons but >I am not sure if it is winning for white > >Is Ba2 clearly better than other posiiible moves like Nxe6? > >Here is Deep Fritz's analysis after Ba2 and after Nxe6 >and After Ba2(I give only depth 13 because smaller >depthes are not interesting) > >New position >r1bqk2r/ppp1nppp/4p3/n5N1/3Pp3/P1P5/B1P2PPP/R1BQK2R b KQkq - 0 1 > >Analysis by Deep Fritz: > >1...b6 2.Qh5 Ng6 3.0-0 Bb7 4.Bxe6 fxe6 5.Nxh7 Kf7 6.Ng5+ > = (0.00) Depth: 13/41 00:01:35 52878kN > >(Blass, Tel-aviv 27.12.2001) > >After Nxe6 >New position >r1bqk2r/ppp1nppp/4N3/n7/2BPp3/P1P5/2P2PPP/R1BQK2R b KQkq - 0 1 > >Analysis by Deep Fritz: > >1...Bxe6 2.Bxe6 0-0 3.Ba2 c5 4.Bg5 h6 5.Bh4 cxd4 6.cxd4 Qc7 7.Bxe7 > = (-0.03) Depth: 13/37 00:01:20 46390kN > >(Blass, Tel-aviv 27.12.2001) > > >second example is WAC 31 > >[D]rb3qk1/pQ3ppp/4p3/3P4/8/1P3N2/1P3PPP/3R2K1 w - - >bm Qxa8 d6 dxe6; id "WAC.031 > >Qxa8 is a bad move and I do not understand how it is one of >the solutions > >d6 dxe6 are good moves and g3 is also a winning move that does not appear in the >solutions > >I already tested my program in the first >31 problems of WAC and it could solve almost all of them >in less than a second. > >The only problem that it could not solve in a reasonable time >is WAC 2 >I guess that it needs depth 13 in order to solve it >and the estimated time that >it needs to get this depth is at least some hours. > >The hardest problem for it >(from the problems that it solved) was WAC 22 >but I consider it as a positional problem because >there are many moves that win a pawn for white to get equality >in material. > >Qh5 is one of them and my program found Nxf7 at depth 4 >but changed it's mind at depth 6 to Qh5 only to change >it's mind later again to Nxf7 at depth 7. > >The search techniques are similiar to TSCP except >limiting the qsearch to 7 plies > >I believe that it is illogical to let the qsearch to explode >and it is also illogical to let it to explode only when the >program search deeper. > >Qsearch is selective search and if you search many plies >forward then you cannot trust your score and >if you cannot trust your score there is no logical reason >to waste more nodes in order to find a score and >it seems better to me to save time and to >return static evaluation. There are a few bugs in WAC.EPD. Try this one instead: ftp://cap.connx.com/pub/EPD/wacnew.epd On a few rare occasions, there are other moves that win for certain.
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