Second induction step of the completeness lemma for parse-alt-rest.
Theorem:
(defthm parse-alt-rest-when-tree-list-match-induction-step-2 (implies (and (not (mv-nth 0 (parse-alt-rest-comp input))) (< (len (mv-nth 2 (parse-alt-rest-comp input))) (len input)) (pred-alt-rest-comp input) (pred-alt-rest (mv-nth 2 (parse-alt-rest-comp input)))) (pred-alt-rest input)))