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