Author: Omid David Tabibi
Date: 06:05:52 08/21/03
Go up one level in this thread
On August 21, 2003 at 07:25:04, Uri Blass wrote: >On August 21, 2003 at 07:18:47, Uri Blass wrote: > >>On August 21, 2003 at 07:06:20, Omid David Tabibi wrote: >> >>>On August 21, 2003 at 06:12:12, Jouni Uski wrote: >>> >>>>[D]8/1p6/1Pp2N1q/p1Ppk2p/P3p3/3PPpPp/3K1P1P/1R6 w - - >>>> >>>>From CSS forum: Machine should, within a million hours, be able to find the draw >>>>in this position (with Ng4+). But Shredder 7.04 found it in one second!! >>>> >>> >>>It is not a draw. The black queen will penetrate into the white cvamp via a6. >>>For the past year I've been working on endgame blockage detection. I noticed >>>that Shredder has some very limited form of blockage detection, but it is very >>>inaccurate, and in many positions I tried, that inaccurate blockage detection >>>wreaked havoc to the search tree. >> >>Wrong >> >>It is a draw >>I also believed that it is not a draw but trying to win it >>against shredder I got the following game >> >>[Event "?"] >>[Site "?"] >>[Date "????.??.??"] >>[Round "?"] >>[White "New game"] >>[Black "?"] >>[Result "*"] >>[SetUp "1"] >>[FEN "8/1p6/1Pp2N1q/p1Ppk2p/P3p3/3PPpPp/3K1P1P/1R6 w - - 0 1"] >>[PlyCount "11"] >> >>1. Ng4+ hxg4 2. d4+ Ke6 3. Rh1 Qf8 4. Ke1 Qa8 5. Kf1 Qa6+ 6. >>Kg1 and black cannot make progress >> >>Uri > >Here is some analysis of shredder in a non draw position >Shredder believes that black advantage is very small >until seeing the win by search. > >I believe that shredder's score for maybe fortress position >is too small and +1 for black is more realistic for >a position that may be in significant part of the cases a win >for the stronger side. When the program is 100% certain about the existence of an unbreakable blockage, it should give it the draw score (0.00) regardless of material advantage. For example, in the following position Genesis is certain about the blockage and gives it 0.00 instantly: [D]8/1k4pp/pP1pb3/P1p2pP1/2B2P2/3P3P/1K1P4/8 b - - 0 1 depth time nodes score variation 1/ 4-> 0.02 0k 1.65 1...e6d7 2/ 6-> 0.02 0k 1.61 1...d6d5 2.c4b3 3/ 8-> 0.02 0k 0.00 1...e6c4 2.d3c4 g7g6 4/ 8-> 0.02 0k 0.00 1...e6c4 2.d3c4 g7g6 5/ 8-> 0.03 1k 0.00 1...e6c4 2.d3c4 g7g6 6/ 9 0.03 1k 0.00 1...e6c4 2.d3c4 g7g6 6/ 9-> 0.03 2k 0.00 1...e6c4 2.d3c4 g7g6 7/10 0.04 3k 0.00 1...e6c4 2.d3c4 g7g6 7/10-> 0.04 4k 0.00 1...e6c4 2.d3c4 g7g6 8/13 0.05 7k 0.00 1...e6c4 2.d3c4 g7g6 8/13-> 0.06 9k 0.00 1...e6c4 2.d3c4 g7g6 9/15 0.08 14k 0.00 1...e6c4 2.d3c4 g7g6 9/15-> 0.11 21k 0.00 1...e6c4 2.d3c4 g7g6 10/15 0.14 30k 0.00 1...e6c4 2.d3c4 g7g6 10/15-> 0.19 45k 0.00 1...e6c4 2.d3c4 g7g6 11/17 0.23 60k 0.00 1...e6c4 2.d3c4 g7g6 11/17-> 0.35 98k 0.00 1...e6c4 2.d3c4 g7g6 12/18 0.42 123k 0.00 1...e6c4 2.d3c4 g7g6 12/18-> 0.66 200k 0.00 1...e6c4 2.d3c4 g7g6 13/19 0.82 248k 0.00 1...e6c4 2.d3c4 g7g6 13/19-> 1.34 423k 0.00 1...e6c4 2.d3c4 g7g6 14/22 1.62 517k 0.00 1...e6c4 2.d3c4 g7g6 14/22-> 2.66 857k 0.00 1...e6c4 2.d3c4 g7g6 15/23 3.03 985k 0.00 1...e6c4 2.d3c4 g7g6 15/23-> 5.23 1735k 0.00 1...e6c4 2.d3c4 g7g6 ---------------------------------------------------------- Without the block detection knowledge, it is very hard to find the correct move 1...Bxc4.
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