[computer-go] KO in Hashtable-UCT?

[John Tromp]

On 5/18/07, Peter Drake <drake at lclark.edu> wrote:
> It took me a long time to get around my mental block and accept the advice
> of everyone here, but your intuition is correct: superko is so rare, and so
> expensive to detect, that you should NOT check for it on every move.

In dimwit, we check for superko while descending the UCT tree,
and only check basic ko in the MC playouts. Our check involves
a single lookup (of the current, incrementally computed Zobrist key)
in a hash_map of previous Zobrist keys, which is not all that expensive.
I agree that doing superko checks in MC playouts would cause an
unnecesary slowdown.

regards,
-John