Excellent idea Chris! Of course you could also hash the hash! But then we are talking about using even more CPU time.
- Don Chris Fant wrote: > Another thing about Zobrist hashes... after you select the canonical > hash, you will end up with a non-uniform distribution. If this value > is going to be used in binary tree, you may wish to swap the low-order > bits with the high-order bits to keep the tree more balanced. > > > On Dec 19, 2007 10:44 AM, Don Dailey <[EMAIL PROTECTED]> wrote: > >> I actually have a routine in Lazarus that rotates a full board. It's >> called transformBoard() and it takes 2 arguments - a board to rotate and >> a transformation (0 through 7) and returns a new rotated board. >> >> I don't use it much except for debugging or stuff done at the root, >> because there are faster ways to do things. >> >> I also have a routine called canHash() which returns a canonical hash >> of the board by trying all 8 transformations and returning the lowest >> valued one. It is more efficient (but not efficient) because it >> doesn't actually produce a new board - it just builds 8 hashes of the >> board from scratch without touching anything. This routine is only >> used at the root for storing opening book moves. >> >> You can use zobrist hashing for maintaining all 8 keys incrementally, >> but you probably need a fairly good reason to do so. Incrementally >> updating of 1 key is almost free, but 8 might be noticeable if you are >> doing it inside a tree search or play-outs. It depends on how "fat" or >> "lean" your program is. Even 8 keys may not be noticeable if your >> program does a lot of work at each move (or an end nodes.) If you are >> not, then it doesn't really matter how you do it. >> >> I typically have 2 routines for everything - I have a slow_make() and a >> fast_make() and the fast_make() doesn't care about superko (although it >> checks for simple-ko) or anything that fast play-outs doesn't care >> about. So the fast make doesn't even try to update zobrist keys. >> >> >> - Don >> >> >> >> >> >> >> Ben Lambrechts wrote: >> >>> Hi all, >>> >>> I am planning a fuseki database. >>> Now I got the following problem: how to rotate/mirror the board for a >>> unique representation. >>> >>> $$c >>> $$ +---------------------------------------+ >>> $$ | . . . . . . . . . . . . . . . . . . . | >>> $$ | . . . . . . . . . . . . . . . . . . . | >>> $$ | . . . . . . . . . . . . . . . . . . . | >>> $$ | . . . O . . . . . , . . . . . X . . . | >>> $$ | . . . . . . . . . . . . . . . . . . . | >>> $$ | . . . . . . . . . . . . . . . . . . . | >>> $$ | . . . . . . . . . . . . . . . . . . . | >>> $$ | . . . . . . . . . . . . . . . . . . . | >>> $$ | . . . . . . . . . . . . . . . . . . . | >>> $$ | . . . , . . . . . , . . . . . , . . . | >>> $$ | . . . . . . . . . . . . . . . . 5 . . | >>> $$ | . . . . . . . . . . . . . . . . . . . | >>> $$ | . . . . . . . . . . . . . . . . . . . | >>> $$ | . . . . . . . . . . . . . . . . . . . | >>> $$ | . . . . . . . . . . . . . . . . . . . | >>> $$ | . . . O . . . . . , . . . . . , . . . | >>> $$ | . . . . . . . . . . . . . . . X . . . | >>> $$ | . . . . . . . . . . . . . . . . . . . | >>> $$ | . . . . . . . . . . . . . . . . . . . | >>> $$ +---------------------------------------+ >>> >>> $$c >>> $$ +---------------------------------------+ >>> $$ | . . . . . . . . . . . . . . . . . . . | >>> $$ | . . . . . . . . . . . . . . . . . . . | >>> $$ | . . . . . . . . 5 . . . . . . . . . . | >>> $$ | . . X , . . . . . , . . . . . X . . . | >>> $$ | . . . . . . . . . . . . . . . . . . . | >>> $$ | . . . . . . . . . . . . . . . . . . . | >>> $$ | . . . . . . . . . . . . . . . . . . . | >>> $$ | . . . . . . . . . . . . . . . . . . . | >>> $$ | . . . . . . . . . . . . . . . . . . . | >>> $$ | . . . , . . . . . , . . . . . , . . . | >>> $$ | . . . . . . . . . . . . . . . . . . . | >>> $$ | . . . . . . . . . . . . . . . . . . . | >>> $$ | . . . . . . . . . . . . . . . . . . . | >>> $$ | . . . . . . . . . . . . . . . . . . . | >>> $$ | . . . . . . . . . . . . . . . . . . . | >>> $$ | . . . O . . . . . , . . . . . O . . . | >>> $$ | . . . . . . . . . . . . . . . . . . . | >>> $$ | . . . . . . . . . . . . . . . . . . . | >>> $$ | . . . . . . . . . . . . . . . . . . . | >>> $$ +---------------------------------------+ >>> >>> Both are the same board, but has anyone made an algorithm that rotates >>> the board or an area of the board in a unique way? >>> I don't need the move order, just the "snapshot" of the board. >>> >>> Ben >>> _______________________________________________ >>> computer-go mailing list >>> computer-go@computer-go.org >>> http://www.computer-go.org/mailman/listinfo/computer-go/ >>> >>> >> _______________________________________________ >> computer-go mailing list >> computer-go@computer-go.org >> http://www.computer-go.org/mailman/listinfo/computer-go/ >> >> > _______________________________________________ > computer-go mailing list > computer-go@computer-go.org > http://www.computer-go.org/mailman/listinfo/computer-go/ > > _______________________________________________ computer-go mailing list computer-go@computer-go.org http://www.computer-go.org/mailman/listinfo/computer-go/
