Re: [gnugo-devel] new vital attack pattern

[Paul Pogonyshev]

Martin wrote:
> The following patch fixes ld_owl:413 and ld_owl:414. Effect on the node
> counts is negligible.

Are there any more changes in regressions?

>
>  ;lib(A)==2
>
> +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.
        +-----

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

Regarding pattern constraint: seems good, apart from
`owl_maxeye(*)==1' part, which is too restrictive.  Consider e.g. this
position:

        |OOOOO
        |XXXXO
        |.X.XO
        |.*XOO
        |.OXO.
        +-----

The move at * kills black dragon, but your pattern wouldn't suggest it,
because maximum number of eyes for the big eyespace is 2 (if black
plays A2 or B2).

And two little bits regarding decorations.  It is a common practice to
add short "change log" in pattern comments (in this case, just a
mention of who and when created the file, see e.g. VA53).  And please,
do keep two empty lines between patterns, as they help to visually
distinguish different patterns.  You can see that this convention is
used consistently in all our databases.

If you use Emacs, you might be interested in Emacs major mode for
editing pattern databases.  More info can be found in
`doc/gnugo.info', node `Patterns' / `Editing Patterns'.

Paul