Re: [gnugo-devel] new vital attack pattern

[Gunnar Farneback]

Paul wrote:
> Martin wrote:
> > +Pattern VA54
> > +
> > +X.X     play atari inside one eye to destroy the other eye
> > +*XO
> > +
> > +:8,s,value(15)
> > +
> > +XaX
> > +*BO
> > +
> > +;lib(B)==2 && olib(*)>=2 && owl_eye_size(a)==1 && owl_maxeye(*)==1
> >
> >  # END OF FILE
> 
> The very low value looks artificial, since the move is very logical.
> I assume that you used so low value, because of positions like this,
> where the move doesn't work as intended:
> 
>         |OOOOO
>         |OXXXO
>         |.X.XO
>         |XX.XO
>         |.*XOO
>         |.OXO.
>         +-----

That position doesn't satisfy the owl_eye_size(a)==1 condition.

> Maybe you should instead provide more context in the pattern diagram,
> like this (correct me if it doesn't work for all cases):
> 
>         Pattern VA54
> 
>         ?X?
>         X.X     play atari inside one eye to destroy the other eye
>         *XO

The main attraction of this alternative is that it's more efficient to
invalidate a match geometrically than by constraint.

/Gunnar