%! damm_algorithm(+Number) is semidet. % Succeeds if the number is valid according to the Damm algorithm. damm_algorithm(Number) :- Matrix = [ [0, 3, 1, 7, 5, 9, 8, 6, 4, 2], [7, 0, 9, 2, 1, 5, 4, 8, 6, 3], [4, 2, 0, 6, 8, 7, 1, 3, 5, 9], [1, 7, 5, 0, 9, 8, 3, 4, 2, 6], [6, 1, 2, 3, 0, 4, 5, 9, 7, 8], [3, 6, 7, 4, 2, 0, 9, 5, 8, 1], [5, 8, 6, 9, 7, 2, 0, 1, 3, 4], [8, 9, 4, 5, 3, 6, 2, 0, 1, 7], [9, 4, 3, 8, 6, 1, 7, 2, 0, 5], [2, 5, 8, 1, 4, 3, 6, 7, 9, 0] ], number_codes(Number, Codes), foldl(damm_algorithm(Matrix), Codes, 0, 0). damm_algorithm(Matrix, Code, N0, N) :- Digit is Code - 48, nth0(N0, Matrix, Row), nth0(Digit, Row, N). :- foreach(member(Number, [5724, 5727, 112946, 112949]), ( ( damm_algorithm(Number) -> write(Number is valid) ; write(Number is invalid) ), nl )).