[computer-go] How to cache local tactical searches?

[Mark Boon]

Instead of a bitmap you should use a hash-key of course, the
comparison is much cheaper.

Mark

On 7/31/06, Chrilly <c.donninger at wavenet.at> wrote:
> The eval of Suzie has a ladder-searcher which I plan now to extend to Geta's
> and simple 3-Liberty Problems. Although the ladder-code is reasonable fast,
> in more complicated positions the speed of the eval goes down considerable
> due to the local tacitical search. So far I use the most primitive cache
> method. A hash-table with the global hash-code. Due to iterative deeping
> there are some cache-hits, but the percentage is much lower than with a more
> clever cache-scheme.
> One idea is that the local search marks a Dirty-Bitmap. All the intersection
> which have been visited (and probably also the neighbours of the visited
> stones, because e.g. the status of a ladder-breaker depends also on its
> liberties). The dirty Bitmap and the current Board-Bitmaps are stored. When
> the local search is called again, the old result is used, if the new board
> matches the stored one on the intersections of the dirty bitmap.
> I do not know if the method works in case of ladders at all, e.g. the
> liberties of a ladder breaker can depend on a stone in a completly other
> part of the board. Its not my intention to have a perfect ladder code. The
> question is, if the idea is flawed at all and not only in some tricky
> special cases.
> A also do not know if the BitMap Key is the best way. I am not really
> satiesfied with this idea. One has to store 3 Bitmaps and also the
> comparision is relative slow (but of course much faster than doing the
> search again). Any other suggestions?
>
> Chrilly
>
> _______________________________________________
> computer-go mailing list
> computer-go at computer-go.org
> http://www.computer-go.org/mailman/listinfo/computer-go/
>