I've proven that the Turing-recognizable languages are closed under concatination. And I need to show that they are closed under homomorphism.

But what's really the difference? Doesn't a closure under concat imply homomorphism as well? Or perhaps I misunderstand what homomorphism means when talking about Turing-Recognizable languges?

I've proven that the Turing-recognizable languages are closed under concatenation and I need to show that they are closed under homomorphism.

But what's really the difference? Doesn't closure under concatenation imply homomorphism as well? Or perhaps I misunderstand what homomorphism means when talking about Turing-Recognizable languges?