Combination of parse-alt-rest-comp-when-tree-match-induction-step-1 and parse-alt-rest-comp-when-tree-match-induction-step-2.
Theorem:
(defthm parse-alt-rest-comp-when-tree-match-induction-step-1+2 (implies (and (not (mv-nth 0 (parse-ichar #\/ (mv-nth 2 (parse-*cwsp input))))) (pred-concatenation (mv-nth 2 (parse-*cwsp (mv-nth 2 (parse-ichar #\/ (mv-nth 2 (parse-*cwsp input)))))))) (pred-alt-rest-comp input)))