(VAR x1 )
(RULES 
        a(x1) -> b(b(x1))
        a(b(b(x1))) -> b(b(c(c(c(a(x1))))))
        b(b(x1)) -> c(c(c(x1)))
        c(c(c(b(b(x1))))) -> a(x1)
        
)