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