Re: [gnugo-devel] new vital attack pattern (revised)

[Martin Holters]

sön 2004-01-18 klockan 00.54 skrev Gunnar Farneback:
> Martin wrote:
> > The other problem is what Evan pointed, e.g.
> > 
> > |OOOOO
> > |OO.OO
> > |OOXOO
> > |XX.XO
> > |.X.XO
> > |.*XOO
> > |.OXO.
> > +-----
> > 
> > This wouldn't be matched with
> > 
> > ?X?
> > X.X
> > *XO
> > 
> > but the respective move would still work. The alternative is to leave
> > the upper line out
> > 
> > X.X
> > *XO
> > 
> > and use a constraint. But after some experimenting, I have come to the
> > conclusion that in fact, constraining to one-space-eyes does not yield
> > any real advantages. So my new proposal is somewhat simplified, but
> > still the increase in node counts compared to the unpatched version is
> > negligible.
> 
> I think the relevant constraint is that the eyespace we try to destroy
> can actually provide one eye. If it's already false there's not much
> point in destroying it. I.e. like this:
> 
> Pattern VA54
> # mh New pattern (3.5.4)
> # See ld_owl:413/414
> 
> X.X    play atari inside one eye to destroy the other eye
> *XO
> 
> :8,s,value(45)
> 
> XbX
> *AO
> 
> ;lib(A)==2 && olib(*)>=2 && owl_proper_eye(*) && owl_maxeye(b)>0

Yes, good point. I've just run the complete regression suite with this
change. Effectiveness remains the same, but node counters and CPU time
usage are slightly lower.

For completeness sake, the re-revised patch:

Index: patterns/owl_vital_apats.db
===================================================================
RCS file: /cvsroot/gnugo/gnugo/patterns/owl_vital_apats.db,v
retrieving revision 1.42
diff -u -r1.42 owl_vital_apats.db
--- patterns/owl_vital_apats.db 7 Jan 2004 10:00:20 -0000       1.42
+++ patterns/owl_vital_apats.db 18 Jan 2004 12:16:57 -0000
@@ -921,4 +921,19 @@
 ;lib(A)==2
 
 
+Pattern VA54
+# mh New pattern (3.5.4)
+# See ld_owl:413/414
+
+X.X    play atari inside one eye to destroy the other eye
+*XO
+
+:8,s,value(45)
+
+XaX
+*BO
+
+;lib(B)==2 && olib(*)>=2 && owl_proper_eye(*) && owl_maxeye(a)>0
+
+
 # END OF FILE