If I have a Language A and A is not regular and A is a subset of B, then B can't be regular.
I think this is False. Because I can have
B = {a^m b^n | m,n >= 0}
A = {a^m b^m | m >=0 }
A is not regular and B is regular. And A is a subset of B. So it is possible for B to be regular.
I just a bit confused and want to know if this thought would be correct or not?