nakayama's lemma for noncommutative rings
Proposition
Let \(A\) be a ring, \(M\) a finitely generated module and \(\mathfrak{a} \subseteq \mathfrak{J}\) a subset of the Jacobson radical such that
Then \(M = 0\)
Proof
Assume \(M \neq 0\), then there exists a maximal proper submodule (cf. finitely generated module contains maximal submodule)
Then \(M/N\) is a simple module (cf. correspondence theorem for quotient modules).
Hence it is isomorphic to some \(R/\mathfrak{m}\) for some left maximal ideal \(\mathfrak{m}\).
Then
contradiction