(a4vec-1x) returns an a4vec that evaluates to 4vec-1x under every environment.
Macro:
(defmacro a4vec-1x nil (list 'quote (a4vec (aig-scons t (aig-sterm nil)) (aig-sterm nil))))
Theorem:
(defthm a4vec-1x-correct (equal (a4vec-eval (a4vec-1x) env) (4vec-1x)))