Ben Lambrechts wrote: > I am planning a fuseki database. > Now I got the following problem: how to rotate/mirror the board for a > unique representation.
Other people have already explained the theory so let me give a practical solution. With GNU Go from CVS (3.7.11 is too old) you can do like this (small board example): kebnekaise 860% ./gnugo --mode gtp --boardsize 7 play black C3 = play white E3 = play black C5 = play white E5 = showboard = A B C D E F G 7 . . . . . . . 7 6 . . . . . . . 6 5 . . X . O . . 5 4 . . . + . . . 4 3 . . X . O . . 3 2 . . . . . . . 2 WHITE (O) has captured 0 stones 1 . . . . . . . 1 BLACK (X) has captured 0 stones A B C D E F G invariant_hash = 260eb1ddc749acde The invariant hash is the minimum of 8 Zobrist hashes for the different rotations/translations, like other people have proposed. Notice that you don't need to transform the board to a canonical orientation. Just let the first position you encounter for a specific invariant hash be the canonical position for that hash. Or forget the board entirely and just work with hashes. For convenience there's also: invariant_hash_for_moves black = A7 318e964ed7069379 B7 0373fdd44fdafe00 C7 26f758754b488c86 D7 05b6443c9d60e37d E7 12f40e9983a36311 F7 325059d1da0d1dc6 G7 2e25b88c7212e237 A6 1a23fde0d4c2013a B6 392298324b51f7b0 C6 4e2e21d52cd43b8f D6 15eebcd82563e84e E6 03819ba2084b34c8 F6 2689b6f0ee4586fe G6 255c9056f34a98a2 A5 0d5f205b26b7125f B5 0ed199b674d50654 D5 0ee34df698dac1de F5 11b25345cd62e0c7 G5 20878af3e6c718f4 A4 a460c09fab970d82 B4 0a45921a80779900 C4 114863343dceb090 D4 27be3651d6b14106 E4 597651a0d52c681c F4 5fabee9c42e474a8 G4 12c61843f864fb16 A3 0d5f205b26b7125f B3 0ed199b674d50654 D3 0ee34df698dac1de F3 11b25345cd62e0c7 G3 20878af3e6c718f4 A2 1a23fde0d4c2013a B2 392298324b51f7b0 C2 4e2e21d52cd43b8f D2 15eebcd82563e84e E2 03819ba2084b34c8 F2 2689b6f0ee4586fe G2 255c9056f34a98a2 A1 318e964ed7069379 B1 0373fdd44fdafe00 C1 26f758754b488c86 D1 05b6443c9d60e37d E1 12f40e9983a36311 F1 325059d1da0d1dc6 G1 2e25b88c7212e237 Notice how e.g. D3 and D5 lead to positions with the same invariant hash, as they should. /Gunnar _______________________________________________ computer-go mailing list computer-go@computer-go.org http://www.computer-go.org/mailman/listinfo/computer-go/
