I am graduate student. As you know, the convolution operation satisfy the below equation due to commutative raw. a(n)*b(n)*c(n) = a(n)*c(n)*b(n) In addition, the muliplication operation also satisfy the below equation due to commutative raw. a(n)b(n)c(n) = a(n)c(n)b(n) however, to my knowledge, the below equation was not satisfied; a(n)b(n)*c(n) = a(n)*c(n)b(n) Can I say that "the commutative raw between multiplication operation and convolution operation does not satisfied" ? Futhermore, do you know any reference for this phenomenon? Best Regards,