Author: Robert Hyatt
Date: 18:37:57 03/07/06
Go up one level in this thread
On March 07, 2006 at 18:48:29, Stuart Cracraft wrote: >On March 07, 2006 at 15:36:11, Robert Hyatt wrote: > >>On March 07, 2006 at 03:49:47, Richard Pijl wrote: >> >>>>If one's results do not rotate approximately as described >>>>for the four positions and you say the evaluation is an >>>>issue, what kinds of evaluation issues have you seen that >>>>could explain it?!? >>> >>>I had this problem long time ago in the Baron as well. To be able to detect >>>these issues I created a little tool that reads a large PGN file, and for every >>>position in the PGN file calls the static evaluation function for that position >>>mirror the position and call static eval again. Whenever that didn't give >>>exactly the same score for both positions, I print both fens, and continue. >>>Usually, if there is an evaluation mirroring bug, it doesn't take long for it to >>>find it. >>> >>>Richard. >> >> >>I've also had this forever it seems, in the "evtest" code in crafty. I have >>'flip' (reverse board, make white pieces black and vice-versa, then copy >>exchange ranks 1 and 8, 2 and 7, etc. I also have a "flop" command that just >>exchanges files a and h, b ahd g, etc, but doesn't change the color. I then do >>something like: >> >>s1 = evaluate() >> >>flip >> >>s2 = evaluate() >> >>flop >> >>s3 = evaluate() >> >>flip >> >>s4 = evaluate() >> >>and the scores must match, except that after a flip the sign must change since >>the pieces are changing. My current code will run through several thousand FEN >>positions with nary a complaint since I no longer have any asymmetry >>whatsoever... > > >Congratulations - not just on the truly great description but on your >perfect multi-lateral symmetry. > >Is this what it means to be balanced? > >Stuart No. That is what it means to be "symmetric". Balanced usually means that various components of the program are "in sync". So that the program is happy in tactical positions, quiet positions, endgame positions, opening positions, etc. If a program is not "balanced" then it has some particular aspect of the game that it does better than others. And good opponents will push you into those kinds of positions where you are worse, and take advantage of the lack of skill there...
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