RE: [gnugo-devel] Proposed owl_determine_life() improvement

[Portela Fernand]

Dan wrote:

> While we're on the subject of owl_determine_life, here's an
> example of a not too uncommon type where something goes 
> seriously wrong. I think this example is worth pondering.
> (...)
> But we have the following around line 2020 in do_owl_defend:
> 
>    if (eyemax < 2 && stackp > 2)
>      move_cutoff = 99; /* Effectively disable vital moves. */

I didn't try yet to find alternatives to this policy. I suspect it
would cause quite a bunch of problems. I'm ready to investigate more,
but I'd need more examples like this one. Can you provide some Dan ?


For this specific case though, I found something which is worth
considering IMO. When you look at D622, it seems that the database
already has the move. It suffices to exchange the marked points :

->*OX?       solidify eye and threaten to make more on the edge
->OXOo
  ....
  ----

I tested that a D622a pattern like this solves nngs4:30 and I'm
currently running the regression tests to see what happens elsewhere.

/nando

PS: I'm wondering if it would be interesting to modify mkpat.c to
accept wildcards like :

*OX?
*XOo
....
----

which would generate

OOX? and *OX?
*XOo     OXOo
....     ....
----     ----

with the same set of constraints (if present)