Don Dailey wrote:
After 842 games with 19x19 go the version with the 3-4-5 line rule is
scoring about 55%
I thought it might do better, I think the rule is reasonably sound - but
55% is pretty respectable for such an easy change and it hardly slows
down the search at all.
Rank Name Elo + - games score oppo. draws
1 d2p 2037 12 12 842 55% 2000 0%
2 base 2000 12 12 842 45% 2037 0%
You are using the rule for move selection during the playouts and the
search, right?
I think such a change may make engine objectively stronger while making
it more vulnerable against humans. Even if the human opponent isn't
aware of the move pruning logic initially, it wouldn't take a lot of
games to figure out that the computer never makes a move away from the
last move to the center or to the sides. Once the player understands the
reason (because the engine never _considers_ such moves) building traps
should be very easy for a good go player. For example, start a losing
ladder towards the center on one side, then start another losing ladder
to the center from another side, such that a ladder breaker in the
center can break both ladders. Now the engine would play thinking all of
its stones in the ladder are safe, oblivious to the fact it will be able
to rescue only one group of them, if a move to the center is made. Of
course the same idea may be used by a programmer to specifically build
an engine stronger against engines with 3-4-5 rule too.
The engine should at least allow _opponent_ to break the rule in the
search tree. That is quite a bit harder to exploit. Now the player must
find moves with refutations outside of the allowed search window. But
there is now the problem of increased evaluation difference between odd
and even depths (as one "player" is objectively stronger.)
Therefore I think you shouldn't let engine prune in the tree with *any*
simple heuristic rule, no matter how often that rule is a useful guide.
OTOH pruning in the playouts seems safe enough. Does that increase
strength too?
_______________________________________________
computer-go mailing list
computer-go@computer-go.org
http://www.computer-go.org/mailman/listinfo/computer-go/
