Author: Robert Hyatt
Date: 17:37:43 10/13/98
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On October 13, 1998 at 18:41:22, Mark Young wrote: >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... > >It happens to the best of us. I wonder if this simple idea of driving the king >to the edge, then to the corner is what the Grandmaster's caught onto so quickly >after only drawing the first few times, or did they find some other idea that >also works. No.. there's more to it than that... the main problem is the rook on the opposite board, checking the king at the right time, also preventing the king and queen from getting on the same rank or file for a skewer... and the check lets the king "out" to the other side where it has to be done again, and once it it out, the 50 move counter usually ends the game. I am utterly amazed that a 5 second search can solve this. Had you told me this a year ago I'd have laughed. As it was I was skeptical. And when I saw it I was *still* skeptical and was looking for a setup error in my experiment. I still want to try at 1 sec / move however... but this is definitely easier than KBN K now... to the computer, because it takes a special piece/square table to win, since you have to drive to the right corner as well...
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