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

[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

/Gunnar