Re: [gnugo-devel] attack_either patches analysis

[Arend Bayer]

Dan wrote:
> About Evan's defend_both patch, and Arend's updating of Arend wrote:
>
> > What remains to do is a measurement whether your patches have a negative
> > performance impact.

> A net increase of about 54 seconds or 4.5%.

This probably means the patch in its current form is not worth its costs.
However, looking at the code, improvements can be made.

Just looking at attack_either(): We should

1. just return asuccess when the other string is safe, i.e.
        if countlib(bstr) >= 5 or maybe 4
2. similar if stackp > branch_depth
3. really not worry about ko results when you've already called
        defend_both() (you simply cannot do that when you don't use a
        komaster scheme).
4. try to return as soon as possible (i.e. insert
        if (defend0 != 0)
          return defended0;
        between the two alibs trymove's
5. maybe worry about not playing the same move twice (in case they
        have common liberties).

Evan, do you want to give (some of) it a try?


Arend