Function:
(defun vcd-index->codestr (x) (declare (xargs :guard (natp x))) (let ((__function__ 'vcd-index->codestr)) (declare (ignorable __function__)) (reverse (coerce (vcd-index->codechars x) 'string))))
Theorem:
(defthm stringp-of-vcd-index->codestr (b* ((code (vcd-index->codestr x))) (stringp code)) :rule-classes :type-prescription)
Theorem:
(defthm vcd-index->codestr-of-nfix-x (equal (vcd-index->codestr (nfix x)) (vcd-index->codestr x)))
Theorem:
(defthm vcd-index->codestr-nat-equiv-congruence-on-x (implies (nat-equiv x x-equiv) (equal (vcd-index->codestr x) (vcd-index->codestr x-equiv))) :rule-classes :congruence)