f true xs f eq s length xs length cons a xs append cons a nil xs length nil 0 length cons x xs s length xs eq 0 0 true eq s x 0 false eq 0 s y false eq s x s y eq x y append nil ys ys append cons x xs ys cons x append xs ys f 2 true 0 eq 2 s 1 length 1 cons 2 a 0 append 2 nil 0 0 0 false 0 FULL emmes-nonloop-ex7_2.trs