Author: Uri Blass
Date: 20:00:19 12/22/00
Go up one level in this thread
On December 22, 2000 at 16:12:35, Rob Shultz wrote: >On December 22, 2000 at 15:52:19, Ernst A. Heinz wrote: > >>>On December 22, 2000 at 14:45:03, Ernst A. Heinz wrote: >>> >>>>>Did you look at what happens if you play a4? Your kingside gets totally >>>>>shredded, starting with Qxf7+... >>>> >>>>Yes, true -- but then Black's King is not standing there! >>>> >>>>It rather seems quite safe on d8 while White's King gets >>>>into mighty trouble on d1 after the sequence a4 - Qxf7+ - >>>>Kd8 - Qxg7: >>>> >>>>[d]2rk3r/6Q1/4p3/1pqpP3/p3b1PP/1B6/PPP2R1R/2K5 b - - 0 1 >>>> >>>>"DarkThought" quickly scores this as substantially positive >>>>for Black, locking onto Qe3+ as the best move almost instantly. >>>> >>>>=Ernst= >>> >>>I have no doubt that black might actually be winning here. But that wasn't >>>the point. You said you picked a4 at depth=10. For that to happen, you have >>>to ignore king safety and sit in the middle of the board, with a queen at f7, >>>a rook on the open file, the king rook hanging, the king can't move to connect >>>the rooks, etc. >>> >>>IE at 10 ply it is all judgement, not "truth" as the search probably can't see >>>the final outcome. >> >>"DarkThought" gets a fail-low on 0-0 in iteration #10 with the >>score dropping from +1.1 in iteration #9 to just +0.39. Then, >>it locks onto a4 and shows the correct PV for it already in >>iteration #10 (with the white King being driven to d1 where it >>is similarly exposed as the black King on d8). >> >>So, why should that mean to ignore king safety or all the other >>evaluation stuff you are talking about above? >> >>To me, it simply looks like our search picks up the crucial >>threats earlier (maybe, by means of more appropriate extensions >>in this particular case) -- no more, no less. >> >>=Ernst= > >Chess Tiger 13.0 likes Rc7. I ran it on a PII 450 with 48MB hashtable. > >00:00:00.8 0.44 6 44059 Qe7 c3 b4 c4 Qd7 Qg5 dxc4 >00:00:00.0 0.46 7 91889 Qe7 a3 a4 Ba2 Rc7 c3 Bg6 >00:00:02.1 0.12 8 324422 Qe7 a4 b4 h5 Rc7 h6 gxh6 Rxh6 Rxh6 Qxh6 Kd7 >00:00:04.0 0.24 8 476754 Qc7 a3 a4 Ba2 Qe7 h5 Rh6 Rf1 >00:00:05.0 0.74 8 639803 Rc7 Rh3 Qe7 a4 b4 h5 Qc5 Rh4 >00:00:07.2 0.72 9 806572 Rc7 a3 a4 Ba2 b4 axb4 Qxb4 c3 O-O Kd1 >00:00:11.2 0.74 10 1290158 Rc7 a3 a4 Ba2 b4 axb4 Qxb4 c3 O-O Kd1 Qc5 >00:00:19.1 0.92 11 2291923 Rc7 a3 a4 Ba2 b4 axb4 Qxb4 c3 O-O Kd1 Qc5 Ke2 >00:00:43.2 1.40 12 5323176 Rc7 a3 a4 Ba2 b4 axb4 Qxb4 Qe3 O-O Rf1 Rb8 Qa3 Qd4 >00:01:30.0 1.12 13 11353422 Rc7 a3 a4 Ba2 b4 axb4 Qxb4 c3 Qe7 Qg5 Qxg5+ hxg5 >Rxh2 Rxh2 a3 Rh8+ Kd7 >00:03:54.0 1.26 14 30268218 Rc7 a3 a4 Ba2 b4 axb4 Qxb4 Qe3 O-O c3 a3 Kd1 Qe7 Ke1 >Rfc8 bxa3 Rxc3 >00:14:02.7 1.16 15 117114018 Rc7 a3 a4 Ba2 b4 axb4 Qxb4 Qe3 O-O c3 a3 Kd1 Qe7 >Ke1 Rb8 bxa3 Qxa3 > >Rob If you wait enough you will find that tiger changes its mind and find a4 at depth 15 when the score is clearly better(I think about +2 but I do not remember). It can take some hours(It took almost 2 hours on my pIII450). Uri
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