Author: Robert Hyatt
Date: 07:58:22 05/28/03
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On May 28, 2003 at 01:08:48, Terry McCracken wrote: >On May 28, 2003 at 00:10:32, Robert Hyatt wrote: > >>On May 27, 2003 at 19:11:49, Jorge Pichard wrote: >> >>>After being completely out-played for the entire game, and with imminent defeat >>>on the horizon, Kasparov resigned the 2nd game rather than drag out the >>>humiliation. But Deep Blue had made a critical error, allowing Kasparov a >>>perpetual check. The analysis is quite deep and extends slightly beyond Deep >>>Blue's search horizon. And, apparently, also Kasparov's. Kasparov's team, which >>>included Grandmaster Yuri Dokhoian and Frederic Friedel, were faced with the >>>delicate task of revealing the news to Kasparov. They waited until lunch the >>>next day, after he had had a nice glass of wine to drink. After they revealed >>>the hidden drawing resource, Kasparov sunk into deep thought (no pun intended) >>>for five minutes before he conceded that he had missed a draw. He later claimed >>>that this was the first time he had resigned a drawn position. >>> >>>Six years later, which program can see the draw in the famous 2nd game of the >>>rematch? >>> >>>Jorge >> >> >>NO program sees this. It is about 60 plies deep. It is unlikely that a >>program will see it for quite some time to come, in fact... > >Bob, is it possible to give a programme just enough knowledge when this kind >of position occurs that a type of quiescense search and extensions is employed >to seek for perpetuals checks, thus reducing the number of plys substantially, >to complete such a task? The draw PV is about 60 plies long. I think Ed posted the analysis on his web site at some point after the 1997 match, although I don't know if it is still there or not. It should be possible to find this draw, but the problem is that it is going to kill performance on other similar positions where there is no draw, but where the program still searches way too deeply wasting a lot of time. > >Or is it too complex and costly to add this type of search? If indeed this type >of search would work in the first place? The problem, as always, is to search the "good positions" and exclude the "useless positions." But that is far easier said than done. > >Here is a primitive example is how the Mach III Master found a mate in 11 with >only ply search, 4 iterations due to checks and captures, in less than a second! > >Of course this isn't the same thing but could it be expanded to find such >difficult draws quickly or at least in a reasonably short time? Many programs find deep mates. Quickly. And they also lose depth in other positions following the same kinds of checks that happen to lead nowhere. > >[D]1kbr3r/pp6/8/P1n2ppq/2N3n1/R3Q1P1/3B1P2/2R2BK1 w > >Terry
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