Am Freitag, den 19.03.2010, 22:38 +0100 schrieb Gunnar Farnebäck: > Martin Holters wrote: > > I arend2:10, after two steps of reading (b G3 w F4), the situation looks > > like this: > > > > 6|...O.... > > 5|..O.X... > > 4|...X.O.. > > 3|..OX.OX. > > 2|..OOXX.. > > 1|........ > > +-------. > > ABCDEFGH > > > > Here, gnugo misses the nice move at H5, capturing the two white stones, > > rejecting G3 in the first place. (G5 instead of H5 does not work, as > > then white can force his way out with a series of ataris after w G4 b > > H4, starting at H3.) > > Agreed. > > > The patch below solves this, adding a suitable attack pattern. > > Nice, it's a very useful technique. > > > However, it breaks strategy5:225 and ninestones:40. In the latter, > > the semeai reading looks bogus with and without the patch and I have > > not really figured out why the patch results in preferring D2 over > > C3. > > I agree about ninestones:40. D2 is extremely ugly but C2 just isn't > working either.
Maybe we should revise the regression test accordingly, also forbidding C2? > > In strategy5:225, the now proposed move L11 matches exactly the pattern > > and indeed looks quite interesting, but IMHO does not work in this > > situation (some better Go player please confirm), but gnugo misses the > > correct defense in the reading process. If time allows, I will > > investigate this further and might add a suitable defense pattern in the > > coming days. > > I'm not sure I'm strong enough to tell either but to me it looks like > L11 doesn't quite work as an owl attack. On the other hand it looks > perfectly playable, strengthening the position while white runs away. > Yes, strategically L11 might be ok, but the OWL reading is definitely not convincing here. > > /Martin > > > > diff --git a/patterns/owl_attackpats.db b/patterns/owl_attackpats.db > > index ee75579..3db44e3 100644 > > --- a/patterns/owl_attackpats.db > > +++ b/patterns/owl_attackpats.db > > @@ -1853,6 +1853,26 @@ X.O > > :/,n,value(90) > > > > > > +Pattern A426 > > +# See e.g. arend2:10 > > + > > +?..? > > +*..O > > +..Y? > > +.O?? > > + > > +:8,-,value(80) > > + > > +?ab? > > +*..O > > +CDe? > > +fG?? > > + > > +; lib(G) == 3 && lib(e) > 2 && xplay_defend(D,C,f,G) > > Maybe oplay_defend(*,D,C,f,G) instead? > > > +; && (owl_escape_value(a) > 0 || owl_escape_value(b) > 0 > > +; || owl_escape_value(C) > 0) > > These should be somewhat better to have before the reading part of the > constraint, to save time. > > /Gunnar Agreed, I will revise the constraints accordingly. /Martin _______________________________________________ gnugo-devel mailing list [email protected] http://lists.gnu.org/mailman/listinfo/gnugo-devel
