Re: [gnugo-devel] Owl mistake and thrashing dragons.

[bump]

Gunnar wrote:

> White is dead, even way dead, but starts thrashing with P7. GNU Go has
> a very clear lead and can easily afford a local reply. As it happens
> we have a policy to attack thrashing dragons, but the implementation
> is not good enough, as this example will show.

This does seem to be an area where a big improvement is possible
and this looks like an excellent test case.

At least the thrashing dragons are found in each case, and B is
known to be ahead. The problem is that the steps that are taken

One thing is that in genmove.c, revise_thrashing_dragon is not
called if a move bigger than 10 points is found on the board.
This may be something we want to change.

This is not the problem at move 220. Unfortunately revise_thrashing_dragon
only revises the status of the single stone at P7, which is not
amalgamated with the big dragon. But if you change the thrashing
dragon to R13 and ask to generate a move, GNU comes up with P14,
relevant to the big dragon but not effective as an attack.

I think the real revisions to fix this problem will be in
value_moves.c. For one thing,estimate_strategical_value()
should handle STRATEGIC_ATTACK_MOVE's against thrashing dragons
more aggressively. At move 220, no such moves are found,
however. Perhaps we should have some 'a' patterns which are
ONLY matched if there is a thrashing dragon in the pattern.

Dan