Re: [gnugo-devel] pattern questions

[nando]

Hi,

On 11/27/06, alain Baeckeroot <address@hidden> wrote:
> Hi
>
> In regression test nngs:308 , gg3.7.10 wants M9 which is 1 point gote.
> There are other much better moves (nearly 6 pts gote, 2 gote, 1 sente)
>
> First pass move génération gives:
> pattern 'DD6'+1 matched at M9
> pattern 'DD6'+6 matched at M9
> pattern 'DD6'+3 matched at M9
> pattern 'DD6'+4 matched at M9
> pattern 'Sente13'+2 matched at M9
>
> and value 0 for M9
> then a second pass due to endgame is done and wrongly choose M9.
>
> I read the doc, but so far dont understand everything :(
>
> Q1/ what means +1 +6 after the DD6 ?

I believe, it's the orientation which matched (out of the 8 possible
ones). In this case, it seems the symmetry set for the pattern is
actually wrong and should be a '+'.

> Q2/ M9 is gote, so i'm surprised to see "Sente13" pattern
>
> Pattern Sente13
> # gf Revised constraint. (3.1.20)
>
> *O
>
> :-,sO
>
> *a
>
> ;lib(a) == 2 && !attack(a) && safe_xmove(*) && safe_omove(*)
> # Action adds a reverse followup value.
> >defend_against_atari(a)
>
> I agree M9 seems sente, but the problem is after opponent answer
> we must capture to defend our string in atari, so it is gote.
> I tried to put lib(a)>=3 ... this crashed gnugo :)

I haven't looked in detail, but since the pattern is meant to find
reverse-sente moves (moves which prevent a direct threat, here an
atari), maybe you want to try to add a "olib(*)>2" clause in the
constraint. Not sure it'll help though.

-- nando