Tree matching theorem for parse-case-insensitive-string.
Theorem:
(defthm tree-match-of-parse-case-insensitive-string (b* (((mv error? tree? &) (parse-case-insensitive-string input))) (implies (and (not error?) (equal element (element-rulename *case-insensitive-string*))) (tree-match-element-p tree? element *grammar*))))