binary_operation(or, t, t, t).     % disjunction
binary_operation(or, t, f, t). 
binary_operation(or, f, t, t).
binary_operation(or, f, f, f).

binary_operation(and, t, t, t).	   % conjunction
binary_operation(and, t, f, f).
binary_operation(and, f, t, f).
binary_operation(and, f, f, f).

binary_operation(xor, t, t, f).	   % exclusive or
binary_operation(xor, t, f, t).
binary_operation(xor, f, t, t).
binary_operation(xor, f, f, f).

binary_operation(eqv, t, t, t).    % equivalence
binary_operation(eqv, t, f, f).
binary_operation(eqv, f, t, f).
binary_operation(eqv, f, f, t).

binary_operation(imp, t, t, t).    % implication
binary_operation(imp, t, f, f).
binary_operation(imp, f, t, t).
binary_operation(imp, f, f, t).

negation(t, f).                     % negation
negation(f, t).