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