(VAR N X XS Y YS )
(STRATEGY CONTEXTSENSITIVE
        (pairNs ) 
        (cons 1) 
        (0 ) 
        (incr 1) 
        (oddNs ) 
        (s 1) 
        (take 1 2) 
        (nil ) 
        (zip 1 2) 
        (pair 1 2) 
        (tail 1) 
        (repItems 1) 
)
(RULES 
        pairNs -> cons(0, incr(oddNs))
        oddNs -> incr(pairNs)
        incr(cons(X, XS)) -> cons(s(X), incr(XS))
        take(0, XS) -> nil
        take(s(N), cons(X, XS)) -> cons(X, take(N, XS))
        zip(nil, XS) -> nil
        zip(X, nil) -> nil
        zip(cons(X, XS), cons(Y, YS)) -> cons(pair(X, Y), zip(XS, YS))
        tail(cons(X, XS)) -> XS
        repItems(nil) -> nil
        repItems(cons(X, XS)) -> cons(X, cons(X, repItems(XS)))
        
)