Function:
(defun bitset-binary-intersect$inline (x y) (declare (type unsigned-byte x) (type unsigned-byte y)) (declare (xargs :guard (and (natp x) (natp y)))) (declare (xargs :split-types t)) (let ((__function__ 'bitset-binary-intersect)) (declare (ignorable __function__)) (the unsigned-byte (logand (the unsigned-byte (lnfix x)) (the unsigned-byte (lnfix y))))))
Theorem:
(defthm natp-of-bitset-binary-intersect (b* ((bitset (bitset-binary-intersect$inline x y))) (natp bitset)) :rule-classes :type-prescription)