Let $R$ be a commutative Noetherian ring with identity. Prove that $R\ncong R\left[x\right]$ and give an example that the result is not true if $R$ is not Noetherian.
It is well known that a vector space always admits an algebraic (Hamel) basis. This is a theorem that follows from Zorn's lemma based on the Axiom of Choice (AC).
Now consider any specific instance of vector space. Since the AC axiom may or may not be included in the underlying set theory, might there be examples of vector spaces in which an Hamel basis actually doesn't exist ?