Addition function
Completion Axiom (
(equal (binary-+ x y) (if (acl2-numberp x) (if (acl2-numberp y) (binary-+ x y) x) (if (acl2-numberp y) y 0)))
(and (acl2-numberp x) (acl2-numberp y))
Notice that like all arithmetic functions,
(thm (equal (+ (fix x) y) (+ x y))) (thm (equal (+ x (fix y)) (+ x y)))