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Tag Archives: flat modules
Commutative Algebra 56
Throughout this article, A denotes a noetherian ring and is a fixed ideal. All Amodules are finitely generated. Consequences of ArtinRees Lemma Suppose we have an exact sequence of finitely generated Amodules Let M be given the 𝔞adic filtration; the induced filtration on … Continue reading
Commutative Algebra 35
Noetherian Modules Through this article, A is a fixed ring. For the first two sections, all modules are over A. Recall that a submodule of a finitely generated module is not finitely generated in general. This will not happen if we constrain … Continue reading
Posted in Advanced Algebra
Tagged flat modules, hilbert basis theorem, ideals, modules, noetherian, projective modules
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Commutative Algebra 34
Nakayama’s Lemma The following is a short statement which has farreaching applications. Since its main applications are for local rings, we will state the result in this context. Throughout this section, is a fixed local ring. Theorem (Nakayama’s Lemma). Let … Continue reading
Commutative Algebra 32
Torsion and Flatness Definition. Let A be a ring and M an Amodule; let . If satisfies , we call it an –torsion element. If is an torsion for some nonzerodivisor we call it a torsion element. M is said … Continue reading
Posted in Advanced Algebra
Tagged algebraic geometry, flat modules, torsion, varieties, zerodivisors
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Commutative Algebra 31
Flat Modules Recall from proposition 3 here: for an Amodule M, is a rightexact functor. Definition. We say M is flat over A (or Aflat) if is an exact functor, equivalently, if A flat Aalgebra is an Aalgebra which is flat as … Continue reading