Re: [gnugo-devel] Eye pattern 304

[Gunnar Farneback]

Paul wrote:
> i came up with inessential marginals to avoid revising pattern databases.
> e.g. in the SP Lee's position we had the following:
> 
>   ...O.
>   XXXOX
>   X....
> 
> which is considered as
> 
>   ..!
> 
> by optics code after domain building. when i made the topological analyser
> understand that the neighbor vertex is marginal too (as a false eye) i got
> this eye:
> 
>   .!!
> 

There seems to be more difficulties of this kind. Appended is a patch
adding the new test case owl1:313. Here the topological analysis finds
that D18 is a false eye, but add_false_eye() doesn't see that it
also should be removed from the eyespace:

Eyespace at A19: color=white border, esize=7, msize=2
A19
B19 (X)
C19
D19 (!)
A18
D18 (!)
A17

.X.!
.  !
.   

  guess_eye - 1111, pessimistic_min=0

With D18 removed, eye pattern 6003 would be matched, finding the vital
point at A18.

> since we don't allow such eyespaces it didn't match. i decided the easiest
> (and maybe the most logical) way would be to just ignore the right marginal,
> matching
> 
>   .!

I agree that it's correct to remove the superfluous margin from the
eyespace, but in light of the failure described above I think we
should make a slightly more drastic change to the code. Instead of
using inessential margins and patching up add_false_eye() to modify
the eyespace in various situations, we should simply rebuild the
eyespaces from scratch after the topological analysis. I believe this
will make the code both simpler and more robust.

/Gunnar

Index: regression/owl1.tst
===================================================================
RCS file: /cvsroot/gnugo/gnugo/regression/owl1.tst,v
retrieving revision 1.59
diff -u -r1.59 owl1.tst
--- regression/owl1.tst 13 May 2003 03:22:53 -0000      1.59
+++ regression/owl1.tst 19 May 2003 19:15:01 -0000
@@ -208,6 +208,10 @@
 312 owl_defend K6
 #? [1 C3]*
 
+loadsgf games/owl45.sgf
+313 owl_attack B18
+#? [1 (A18|C19)]
+
 
 ########### end of tests #####################
 
Index: regression/games/owl45.sgf
===================================================================
RCS file: regression/games/owl45.sgf
diff -N regression/games/owl45.sgf
--- /dev/null   1 Jan 1970 00:00:00 -0000
+++ regression/games/owl45.sgf  19 May 2003 19:15:02 -0000
@@ -0,0 +1,24 @@
+(;GM[1]FF[4]
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