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    !_-fn

    Signature
    (!_-fn alternation) → element
    Arguments
    alternation — Guard (alternationp alternation).
    Returns
    element — Type (elementp element).

    Definitions and Theorems

    Function: !_-fn

    (defun !_-fn (alternation)
      (declare (xargs :guard (alternationp alternation)))
      (element-group alternation))

    Theorem: elementp-of-!_-fn

    (defthm elementp-of-!_-fn
      (b* ((element (!_-fn alternation)))
        (elementp element))
      :rule-classes :rewrite)

    Theorem: !_-fn-of-alternation-fix-alternation

    (defthm !_-fn-of-alternation-fix-alternation
      (equal (!_-fn (alternation-fix alternation))
             (!_-fn alternation)))

    Theorem: !_-fn-alternation-equiv-congruence-on-alternation

    (defthm !_-fn-alternation-equiv-congruence-on-alternation
      (implies (alternation-equiv alternation alternation-equiv)
               (equal (!_-fn alternation)
                      (!_-fn alternation-equiv)))
      :rule-classes :congruence)