Author: John Coffey
Date: 09:18:37 10/14/98
Go up one level in this thread
On October 13, 1998 at 20:37:43, Robert Hyatt wrote: >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... Although i doubt that any program can see the solution all the way through in such short time, I am sure that they can find a position that brings them closer to a solution (such as getting the king to the side of the board or corner, as you have said.) John Coffey
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