[gnugo-devel] optics improvement

[Paul Pogonyshev]

this time a real one ;)

i looked at the reason of owl_rot 244 fail and found this in
topological_eye():

        /* Store these in sorted (descending) order. We remap val
         * differently for attack and defense points according to:
         *
         * val    attack_value     defense_value
         * ---    ------------     -------------
         * 1.0    3                3
         * <1.0   2                1
         * >1.0   1                2
         ...
        else if (val < 1.0) {
          attack_value = 2;
          defense_value = 3;
        }
        else {
          attack_value = 3;
          defense_value = 2;
        }

clearly, version in comments is better since securing diagonals
opponent can control only by winning ko is not so important as ones he
can control unconditionally (val == 1.0). this is just a typo mistake,
i think.

to my mind, it doesn't matter how we place those 1's and 2's as long
as attack and defense values for ko-dependent diagonals are less than
for ones with val == 1.0. double ko is rare enough and as i can see,
one of the two can be won no matter which you play first. however, i
kept the original values (those which are in comments).

i ran modified version with these test files: owl, owl1, owl_rot,
ld_owl, ld_owl_rot, optics and optics_rot and got three PASSes:

owl_rot:244: PASSED: correct: (2|3) F11  answer: 3 F11
owl_rot:245: PASSED: correct: 1 (F11|H8|F8)  answer: 1 F11
ld_owl_rot:179: PASSED: correct: 3 T17  answer: 3 T17

Paul


Index: gnugo/engine/optics.c
===================================================================
RCS file: /cvsroot/gnugo/gnugo/engine/optics.c,v
retrieving revision 1.50
diff -u -r1.50 optics.c
--- gnugo/engine/optics.c       18 Sep 2002 15:10:02 -0000      1.50
+++ gnugo/engine/optics.c       22 Sep 2002 14:07:09 -0000
@@ -1469,10 +1469,10 @@
        }
        else if (val < 1.0) {
          attack_value = 2;
-         defense_value = 3;
+         defense_value = 1;
        }
        else {
-         attack_value = 3;
+         attack_value = 1;
          defense_value = 2;
        }