is_odd(X) :- 1 is mod(X,2).is_even(X) :- 0 is mod(X,2).
is_odd(5). is_even(6). is_odd(4). is_even(1).
GNU Prolog 1.3.1 By Daniel Diaz Copyright (C) 1999-2009 Daniel Diaz yes yes no no
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