Author: Ingo Lindam
Date: 08:36:03 12/07/02
Go up one level in this thread
On December 07, 2002 at 11:25:03, Uri Blass wrote: >On December 07, 2002 at 05:04:33, Ingo Lindam wrote: > >>Hello all, >> >>concerning the current discussion about testing positional skills >>I like to add the following: >> >>I think to evaluate/test positional skills of an chess engine you don't need to >>have positions without tactics (what I think is impossible, because for >>everything true in a chess position there is a tactical proof if you are just >>able to look deep enough into the tree). >> >>We agree that also in a nearly 'tactical solution free' (within a certain scope) >>position with a one and only best move it could happen that the engine plays the >>right move for the wrong reason. >> >>So why not test the other direction? Assume that you have a true evaluation for >>a position. This true evaluation doesn't need to be exact it can also be: "White >>is atleast equal (or better)." So as long as the engine claims a clear advantage >>for black, it fails the test. If the score corresponds with your own evaluation >>you are ofcourse not able to judge about the engine as long as you not checked >>the reason, why it gives this evaluation. Ofcourse your test positions prefers >>the engine to give the wrong evaluation instantly because of e.g. being a pawn >>up. The deeper the engine goes into the search tree keeps to give the wrong >>evaluation the worse is the positional evaluation of the maschine (at least at >>this special kind of positions). And because you know at least one reason, why >>the position shouldn't be judge that worse as the engine does, you should also >>be able to name some/a positional feature/s the engine doesn't evaluate right. >> >>Giving an example: >> >>[D] r3kb1r/1p1q1ppp/p1n1p3/3pN1B1/3Pb3/1Q2P3/PP2BPPP/2R1K2R b Kkq - 0 1 >> >>position after 12.Se5 >> >>Analysis by Fritz 7: >>(sorry for the german letters: S=N,L=B,D=Q,T=R and K=K) >> >>12...Sxe5 13.f3 Sg6 14.fxe4 h6 15.Lf4 Sxf4 16.exf4 dxe4 >>³ (-0.69) Tiefe: 8/21 00:00:00 151kN >>12...Sxe5 13.dxe5 Lxg2 14.Tg1 Le4 15.f3 h6 16.Lh4 Lf5 17.Kf1 >>³ (-0.69) Tiefe: 9/24 00:00:00 400kN >>12...Sxe5 13.f3 Sg6 14.fxe4 h6 15.Lf4 Sxf4 16.exf4 dxe4 17.De3 Lb4+ >>µ (-0.78) Tiefe: 10/27 00:00:01 935kN >>12...Sxe5 13.dxe5 Lxg2 14.Tg1 Le4 15.f3 h6 16.Lf4 Lf5 17.Kf1 Tc8 18.Kg2 >>µ (-0.75) Tiefe: 11/29 00:00:04 2493kN >>12...Sxe5 13.dxe5 Lxg2 14.Tg1 Le4 15.f3 h6 16.Lf4 Lg6 17.Kf1 Le7 18.Ld3 Lxd3+ >>19.Dxd3 >>µ (-0.78) Tiefe: 12/31 00:00:10 5134kN >>12...Sxe5 13.dxe5 Lxg2 14.Tg1 Le4 15.f3 h6 16.Lf4 Lf5 17.Kf1 Tc8 18.Txc8+ Dxc8 >>µ (-0.84) Tiefe: 13/36 00:00:28 15940kN >>12...Sxe5 13.dxe5 Lxg2 14.Tg1 Le4 15.f3 h6 16.Lf4 Lf5 17.Kf1 Tc8 18.Txc8+ Dxc8 >>µ (-0.78) Tiefe: 14/38 00:01:06 39095kN >>12...Sxe5 13.dxe5 Lxg2 14.Tg1 Le4 15.f3 Lf5 16.Kf2 b5 17.Lf4 Tc8 18.Txc8+ Dxc8 >>µ (-0.84) Tiefe: 15/42 00:02:47 102460kN >>12...Sxe5 13.dxe5 Lxg2 14.Tg1 Le4 15.Db6 Tc8 16.Txc8+ Dxc8 17.Kd2 d4 18.Dxd4 >>Dc2+ >>µ (-0.72) Tiefe: 16/46 00:08:08 293734kN >> >>Still at ply 16 the machine evaluates (in my opinion wrongly) an advantage for >>black, although the PV contains th ebest moves for white in the beginning. >>(going one move back in the position you will see that the engine will not play >>Ne5 within 17 plys). >> >>Giving the engine some more (white) moves towards 16. Kd2 the evaluation will >>change into the right direction. >> >>in the game it follows: >> >>12... Nxe5 13. dxe5 Bxg2 14. Rg1 >>Be4 15. Qb6 Rc8 > > >The question is if 12.Ne5 was the only best move. >I doubt it > >Movei prefers 15...h6 > >Is there a win for white after 15...h6? > >A possible line is 16.Rc7 Qa4 17.a3 hxg5 18.Qxb7 Bb4+ 19.Kf1 0-0 20.Qxb4 Qxb4 >21.axb4 and the endgame seems to be equal. > >Uri My question was not whether Ne5 is doubtless the one and only best move. I am sure...that black is not better here, after white plays Ne5 and nevertheless the engine (Fritz 8) gives a clear advantage to black. And (if I am right) that should be a sign that the positional evaluation of the engine is not optimal is this position here, shouldn't it?
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