Get the prefix field from a dec-expo.
(dec-expo->prefix x) → prefix
This is an ordinary field accessor created by fty::defprod.
Function:
(defun dec-expo->prefix$inline (x) (declare (xargs :guard (dec-expop x))) (declare (xargs :guard t)) (let ((__function__ 'dec-expo->prefix)) (declare (ignorable __function__)) (mbe :logic (b* ((x (and t x))) (dec-expo-prefix-fix (cdr (std::da-nth 0 x)))) :exec (cdr (std::da-nth 0 x)))))
Theorem:
(defthm dec-expo-prefixp-of-dec-expo->prefix (b* ((prefix (dec-expo->prefix$inline x))) (dec-expo-prefixp prefix)) :rule-classes :rewrite)
Theorem:
(defthm dec-expo->prefix$inline-of-dec-expo-fix-x (equal (dec-expo->prefix$inline (dec-expo-fix x)) (dec-expo->prefix$inline x)))
Theorem:
(defthm dec-expo->prefix$inline-dec-expo-equiv-congruence-on-x (implies (dec-expo-equiv x x-equiv) (equal (dec-expo->prefix$inline x) (dec-expo->prefix$inline x-equiv))) :rule-classes :congruence)