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