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    • Stobj-updater-independence

    Range-equal

    Check that a range of entries from two lists are equal.

    Signature
    (range-equal start num x y) → *
    Arguments
    start — Guard (natp start).
    num — Guard (natp num).
    x — Guard (true-listp x).
    y — Guard (true-listp y).

    This is useful for stobj updater independence theorems, e.g.,

    (def-stobj-updater-independence sum-range-of-field2-updater-independence
      (implies (range-equal 0 k (nth 2 new) (nth 2 old))
               (equal (sum-range-of-field2 k new)
                      (sum-range-of-field2 k old))))

    Also see range-nat-equiv, which is similar but checks nat-equiv of corresponding elements instead of equal.

    Definitions and Theorems

    Function: range-equal

    (defun range-equal (start num x y)
           (declare (xargs :guard (and (natp start)
                                       (natp num)
                                       (true-listp x)
                                       (true-listp y))))
           (let ((__function__ 'range-equal))
                (declare (ignorable __function__))
                (if (zp num)
                    t
                    (and (equal (nth start x) (nth start y))
                         (range-equal (1+ (lnfix start))
                                      (1- num)
                                      x y)))))

    Theorem: range-equal-open

    (defthm range-equal-open
            (implies (not (zp num))
                     (equal (range-equal start num x y)
                            (and (equal (nth start x) (nth start y))
                                 (range-equal (1+ (lnfix start))
                                              (1- num)
                                              x y)))))

    Theorem: range-equal-of-nfix-start

    (defthm range-equal-of-nfix-start
            (equal (range-equal (nfix start) num x y)
                   (range-equal start num x y)))

    Theorem: range-equal-nat-equiv-congruence-on-start

    (defthm range-equal-nat-equiv-congruence-on-start
            (implies (nat-equiv start start-equiv)
                     (equal (range-equal start num x y)
                            (range-equal start-equiv num x y)))
            :rule-classes :congruence)

    Theorem: range-equal-of-nfix-num

    (defthm range-equal-of-nfix-num
            (equal (range-equal start (nfix num) x y)
                   (range-equal start num x y)))

    Theorem: range-equal-nat-equiv-congruence-on-num

    (defthm range-equal-nat-equiv-congruence-on-num
            (implies (nat-equiv num num-equiv)
                     (equal (range-equal start num x y)
                            (range-equal start num-equiv x y)))
            :rule-classes :congruence)

    Theorem: range-equal-of-list-fix-x

    (defthm range-equal-of-list-fix-x
            (equal (range-equal start num (acl2::list-fix x)
                                y)
                   (range-equal start num x y)))

    Theorem: range-equal-list-equiv-congruence-on-x

    (defthm range-equal-list-equiv-congruence-on-x
            (implies (acl2::list-equiv x x-equiv)
                     (equal (range-equal start num x y)
                            (range-equal start num x-equiv y)))
            :rule-classes :congruence)

    Theorem: range-equal-of-list-fix-y

    (defthm range-equal-of-list-fix-y
            (equal (range-equal start num x (acl2::list-fix y))
                   (range-equal start num x y)))

    Theorem: range-equal-list-equiv-congruence-on-y

    (defthm range-equal-list-equiv-congruence-on-y
            (implies (acl2::list-equiv y y-equiv)
                     (equal (range-equal start num x y)
                            (range-equal start num x y-equiv)))
            :rule-classes :congruence)

    Theorem: nth-when-range-equal

    (defthm nth-when-range-equal
            (implies (and (range-equal start num x y)
                          (<= (nfix start) (nfix n))
                          (< (nfix n)
                             (+ (nfix start) (nfix num))))
                     (equal (nth n x) (nth n y))))

    Theorem: range-equal-self

    (defthm range-equal-self
            (range-equal start num x x))

    Theorem: range-equal-of-update-out-of-range-1

    (defthm range-equal-of-update-out-of-range-1
            (implies (not (and (<= (nfix start) (nfix n))
                               (< (nfix n)
                                  (+ (nfix start) (nfix num)))))
                     (equal (range-equal start num (update-nth n v x)
                                         y)
                            (range-equal start num x y))))

    Theorem: range-equal-of-update-out-of-range-2

    (defthm range-equal-of-update-out-of-range-2
            (implies (not (and (<= (nfix start) (nfix n))
                               (< (nfix n)
                                  (+ (nfix start) (nfix num)))))
                     (equal (range-equal start num x (update-nth n v y))
                            (range-equal start num x y))))

    Theorem: range-equal-of-empty

    (defthm range-equal-of-empty
            (range-equal start 0 x y))