Author: Roberto Waldteufel
Date: 06:45:41 10/14/98
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On October 13, 1998 at 17:35:34, Robert Hyatt wrote: > >After reading this thread, I decided to run a test myself. I started >off with 20 games of crafty vs crafty, white having KQ and no tablebases, >black having tablebases. At 20 seconds per move, this ended in 20 wins >for white which surprised me. I took several different positions (20 in >total) most of which were mate in 30 or greater and gave crafty 20 secs/move >using 1 cpu on my ALR. All wins. I didn't expect this. > >I then repeated this at 10 secs/move. All wins. > >I then repeated it at 5 secs/move. All wins. I was going to try 1 sec >but decided that to the computer, this is far easier than I thought. It >seems that the simple heuristic drive king to the edge, then to the >corner, is enough. It didn't play it perfectly, but it never slipped more >than 2 moves from optimal at any single move. And when it started off at >mate in 34, the "game" never went past 40 moves. > >So, I retract my original feeling, that KQ vs KR is hard with the KR >side having a database. It seems it is a "trivial" ending regardless of >having them or not. > >Most surprising... In the process of developping Rabbit I have pitted various versions against other programs (mostly Mephisto Risc 1MB, Fritz2 and Gromit) and occasionally good club standard humans. I find this a good way to test overall program performance. I remember once a very early (ie weak) version of Rabbit achieved the stronger side of KQKR, and was also using square-piece codes that encoraged centralisation for own pieces/decentralisation of opponents pieces (this included the kings, since the position was classified as endgame). Surprisingly (to me), Rabbit won this game. I never did any more tests, but your post reminded me how surprised I was, and adds further evidence to your findings that this endgame can be solved with quite elementary heuristics and a reasonable depth search. I never ceased to be amazed at the power of search.....:-) Roberto
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