(VAR X XS )
(STRATEGY CONTEXTSENSITIVE
        (nats ) 
        (cons 1) 
        (0 ) 
        (incr 1) 
        (pairs ) 
        (odds ) 
        (s 1) 
        (head 1) 
        (tail 1) 
)
(RULES 
        nats -> cons(0, incr(nats))
        pairs -> cons(0, incr(odds))
        odds -> incr(pairs)
        incr(cons(X, XS)) -> cons(s(X), incr(XS))
        head(cons(X, XS)) -> X
        tail(cons(X, XS)) -> XS
        
)