Re: [gnugo-devel] nasty shape values

[Gunnar Farneback]

Nando wrote:
> > (...) the mistake was caused by CB328 pattern with shape value of +10.
> 
> FWIW, I also have a (not submitted) test case where CB328 causes a mistake
> worth about 10 points. There has been a discussion about high shape values
> some time ago, with the result that nothing changed. Still, shape(10)
> roughly means doubling the move value whatever this value is, which
> looks a bit unreasonable to me. 

Please submit such tests.

As an experiment I tried to significantly limit the effects of shape
values to a maximum change of 0.95 points, as implemented in the
appended patch (not for CVS). The breakage is large and more negative
than positive. Analysis of these tests may give some insights about
the positive and negative effects of (large) shape values.

trevora:130     FAIL B7 [F4]
nngs1:20        FAIL G3 [F17]
nngs1:34        PASS N15 [!N10|N9|N11|O11|O10]
nngs1:35        FAIL T6 [D13]
nngs1:48        PASS R16 [R16]
golife:4        FAIL B4 [H5]
lazarus:16      PASS L16 [L16]
strategy2:51    FAIL O7 [P3]
strategy2:53    FAIL E10 [S15]
strategy2:54    FAIL P7 [P6]
strategy2:70    PASS N16 [M15|J15|N16|J16]
strategy2:84    PASS Q13 [Q13]
strategy2:90    FAIL F5 [B14|D17]
nicklas1:501    FAIL F6 [G7]
manyfaces:2     FAIL T15 [S16]
trevor:220      FAIL A7 [E8]
trevor:1110     PASS O12 [O12]
nngs:200        PASS O11 [P12|O11]
nngs:590        PASS G3 [G3]
nngs:820        FAIL D14 [J13|L9]
nngs:910        PASS T16 [T16]
nngs:950        FAIL C8 [F1]
nngs:1050       PASS G10 [J10|H10|G10|F10]
trevorc:1570    FAIL E1 [E2|F2|F3]
strategy3:128   FAIL R11 [O8]
global:9        PASS F4 [F4]
arend:38        FAIL O17 [O5]
13x13:12        FAIL H6 [G7|F7|G8]
13x13:36        FAIL B2 [C5]
13x13:37        FAIL E3 [E10]
trevord:200     PASS O11 [O11|E6]
nngs3:310       PASS B5 [C5|B5]
nngs3:470       PASS P11 [!J17]
nngs3:800       FAIL E3 [G4]
nngs4:30        FAIL D5 [C5|C6]
strategy5:224   FAIL O18 [N15]
strategy5:234   FAIL D16 [H14]
century2002:150 PASS B18 [B18]
safety:5        FAIL C15 [K8|L9|L7]
gunnar:19       PASS L4 [L4]
13x13b:22       FAIL A6 [B6|B7]
13x13b:40       FAIL H10 [F8]
13x13b:43       PASS J3 [J3]

/Gunnar

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        26 Feb 2003 21:21:57 -0000
@@ -2590,6 +2590,10 @@
       /* shape_factor has already been computed. */
       float old_value = tot_value;
       tot_value *= shape_factor;
+      if (tot_value > old_value)
+       tot_value = old_value + soft_cap(tot_value - old_value, 0.95);
+      else
+       tot_value = old_value - soft_cap(old_value - tot_value, 0.95);
       if (verbose) {
        /* Should all have been TRACE, except we want field sizes. */
        gprintf("  %1m: %f - shape ", pos, tot_value - old_value);