Basic normalization to move negative terms to the other side of an inequality.
Theorem:
(defthm <-0-minus (equal (< 0 (- x)) (< x 0)))
Theorem:
(defthm <-minus-zero (equal (< (- x) 0) (< 0 x)))
Theorem:
(defthm <-0-+-negative-1 (equal (< 0 (+ (- y) x)) (< y x)))
Theorem:
(defthm <-0-+-negative-2 (equal (< 0 (+ x (- y))) (< y x)))
Theorem:
(defthm <-+-negative-0-1 (equal (< (+ (- y) x) 0) (< x y)))
Theorem:
(defthm <-+-negative-0-2 (equal (< (+ x (- y)) 0) (< x y)))