RE: [gnugo-devel] nasty shape values

[Portela Fernand]

Gunnar wrote:

> Please submit such tests.

Although it was not really necessary, I've been recently reminded that
reviewing patches is a large amount of work for Dan, Arend and you (thank
you all btw). Since my recent test cases submissions proved to be somewhat
imperfect, I was just holding this case in a (soon to be submitted) batch,
until I find the time to review them as carefully as I can.

> As an experiment I tried to significantly limit the effects of shape
> values to a maximum change of 0.95 points (...)

This looks a bit too drastic to me, though it's definitely interesting to
measure the impact of such a change. IMO shape values are important,
and we maybe only need to try to fix their (sometimes) nasty effects.

I just made another experiment with the appended patch (not for CVS either,
just for discussion), which solves the test case I have and plays H8
(instead of M8) in Paul's game. AFAICT, it is otherwise completely neutral
on regressions. Inge's idea was to remove all large shape values, my
experiment is a bit more general, since it limits any shape boost to a
maximum of +40%.

/nando

Index: engine/value_moves.c
===================================================================
RCS file: /cvsroot/gnugo/gnugo/engine/value_moves.c,v
retrieving revision 1.82
diff -u -r1.82 value_moves.c
--- engine/value_moves.c        13 Feb 2003 20:09:42 -0000      1.82
+++ engine/value_moves.c        28 Feb 2003 17:40:06 -0000
@@ -1084,6 +1084,8 @@
     exponent += move[pos].numpos_shape - 1;
   if (move[pos].numneg_shape > 1)
     exponent -= move[pos].numneg_shape - 1;
+  if (exponent > 7)
+    exponent = 7;
   return pow(1.05, exponent);
 }