cnf(a_equals_b_6,negated_conjecture, ( equalish(a,b) )). cnf(c_equals_d_7,negated_conjecture, ( equalish(c,d) )). cnf(add_equals_u_8,negated_conjecture, ( equalish(add(a,c),u) )). cnf(add_not_equal_to_u_9,negated_conjecture, ( ~ equalish(add(d,b),u) )).