svex-apply is almost always monotonic :-(
Theorem:
(defthm svex-apply-monotonic (implies (and (4veclist-<<= x y) (not (eq (fnsym-fix fn) '===)) (or (not (eq (fnsym-fix fn) '===*)) (equal (4veclist-nth-safe 1 x) (4veclist-nth-safe 1 y))) (or (not (eq (fnsym-fix fn) '==?)) (equal (4veclist-nth-safe 1 x) (4veclist-nth-safe 1 y))) (or (not (eq (fnsym-fix fn) 'bit?!)) (equal (4veclist-nth-safe 0 x) (4veclist-nth-safe 0 y))) (or (not (eq (fnsym-fix fn) '?!)) (equal (4veclist-nth-safe 0 x) (4veclist-nth-safe 0 y)))) (4vec-<<= (svex-apply fn x) (svex-apply fn y))))