Nakayama's lemma

From Commalg

This article is about the statement of a simple but indispensable lemma in commutative algebra
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Statement

Let R be a commutative unital ring, and I be an ideal contained inside the Jacobson radical of R. Let M be a finitely generated R-module. Then the following are true:

  1. If IM=M then M=0
  2. If N is a submodule of M suc hthat N+IM=M, then N=M
  3. If m1,m2,,mn have images in M/IM that generate it as a R-module, then m1,m2,,mn generate M as a R-module

Related facts

The graded Nakayama's lemma is a related fact true for graded rings.