		Search-engine friendly clone of the ACL2 documentation.

3bits

3bits-fix

Fixing function for 3bits bit structures.

Signature
(3bits-fix x) → fty::fixed
Arguments: x — Guard (3bits-p x).
Returns: fty::fixed — Type (3bits-p fty::fixed).

Definitions and Theorems

Function: 3bits-fix

(defun 3bits-fix (x)
  (declare (xargs :guard (3bits-p x)))
  (let ((__function__ '3bits-fix))
    (declare (ignorable __function__))
    (mbe :logic (loghead 3 x) :exec x)))

Theorem: 3bits-p-of-3bits-fix

(defthm 3bits-p-of-3bits-fix
  (b* ((fty::fixed (3bits-fix x)))
    (3bits-p fty::fixed))
  :rule-classes :rewrite)

Theorem: 3bits-fix-when-3bits-p

(defthm 3bits-fix-when-3bits-p
  (implies (3bits-p x)
           (equal (3bits-fix x) x)))

Function: 3bits-equiv$inline

(defun 3bits-equiv$inline (x y)
  (declare (xargs :guard (and (3bits-p x) (3bits-p y))))
  (equal (3bits-fix x) (3bits-fix y)))

Theorem: 3bits-equiv-is-an-equivalence

(defthm 3bits-equiv-is-an-equivalence
  (and (booleanp (3bits-equiv x y))
       (3bits-equiv x x)
       (implies (3bits-equiv x y)
                (3bits-equiv y x))
       (implies (and (3bits-equiv x y)
                     (3bits-equiv y z))
                (3bits-equiv x z)))
  :rule-classes (:equivalence))

Theorem: 3bits-equiv-implies-equal-3bits-fix-1

(defthm 3bits-equiv-implies-equal-3bits-fix-1
  (implies (3bits-equiv x x-equiv)
           (equal (3bits-fix x)
                  (3bits-fix x-equiv)))
  :rule-classes (:congruence))

Theorem: 3bits-fix-under-3bits-equiv

(defthm 3bits-fix-under-3bits-equiv
  (3bits-equiv (3bits-fix x) x)
  :rule-classes (:rewrite :rewrite-quoted-constant))