fact(the opposite of $a is $b) => fact(the opposite of $b is $a) fact($x is a string list) => fact(you can take $x 's length) fact($gertrude is a $sheep) && fact($sheep are $afraid_of_wolves) => fact($gertrude is $afraid_of_wolves) $x in eval(mL("Pronouns")) => fact($_q_x is a pronoun) fact($$x) && eval(ai_isQuestion_2($$x)) => fact(Untrue: $$x)