(VAR s t u )
(RULES 
        comp(s,id) -> s
        cons(one,shift) -> id
        cons(comp(one,s),comp(shift,s)) -> s
        comp(one,cons(s,t)) -> s
        comp(shift,cons(s,t)) -> t
        comp(abs(s),t) -> abs(comp(s,cons(one,comp(t,shift))))
        comp(cons(s,t),u) -> cons(comp(s,u),comp(t,u))
        comp(id,s) -> s
        comp(comp(s,t),u) -> comp(s,comp(t,u))
        
)