cons pair, else nil
Major Section: ACL2-BUILT-INS
Completion Axiom (completion-of-cdr):
(equal (cdr x)
       (cond
        ((consp x)
         (cdr x))
        (t nil)))
(or (consp x) (equal x nil))Notice that in the ACL2 logic,
cdr returns nil for every atom.
 
 