Basic equivalence relation for function structures.
Function:
(defun function-equiv$inline (acl2::x acl2::y) (declare (xargs :guard (and (functionp acl2::x) (functionp acl2::y)))) (equal (function-fix acl2::x) (function-fix acl2::y)))
Theorem:
(defthm function-equiv-is-an-equivalence (and (booleanp (function-equiv x y)) (function-equiv x x) (implies (function-equiv x y) (function-equiv y x)) (implies (and (function-equiv x y) (function-equiv y z)) (function-equiv x z))) :rule-classes (:equivalence))
Theorem:
(defthm function-equiv-implies-equal-function-fix-1 (implies (function-equiv acl2::x x-equiv) (equal (function-fix acl2::x) (function-fix x-equiv))) :rule-classes (:congruence))
Theorem:
(defthm function-fix-under-function-equiv (function-equiv (function-fix acl2::x) acl2::x) :rule-classes (:rewrite :rewrite-quoted-constant))
Theorem:
(defthm equal-of-function-fix-1-forward-to-function-equiv (implies (equal (function-fix acl2::x) acl2::y) (function-equiv acl2::x acl2::y)) :rule-classes :forward-chaining)
Theorem:
(defthm equal-of-function-fix-2-forward-to-function-equiv (implies (equal acl2::x (function-fix acl2::y)) (function-equiv acl2::x acl2::y)) :rule-classes :forward-chaining)
Theorem:
(defthm function-equiv-of-function-fix-1-forward (implies (function-equiv (function-fix acl2::x) acl2::y) (function-equiv acl2::x acl2::y)) :rule-classes :forward-chaining)
Theorem:
(defthm function-equiv-of-function-fix-2-forward (implies (function-equiv acl2::x (function-fix acl2::y)) (function-equiv acl2::x acl2::y)) :rule-classes :forward-chaining)