Question

Concatenation of two different language cannot be commutative until atleast one of them is ‘Φ’ or ‘∈

True or false

Comments

I think it is false!

L1= {a} L2 ={aa}

L1.L2 = L2.L1

---

let L1= {a}
L2 ={aa}
then L1.L2 = aaa = L2.L1