Blueprint for the Adjunction Formula

1.6 Support Theory

Definition 1.6.1
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The annihilator of a module M is the ideal of elements \(r \in R\) such that \(rm = 0\) for all \(m \in M\).

Definition 1.6.2
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The support of a module is the set of prime ideals \(\mathfrak {p} \subset R\) such that \(M_{\mathfrak {p}} \neq 0\).

The zero locus of the annihilator of a module is the same as the support of that module. I.e. the set of prime ideals containing the \(\operatorname {Ann}_R(M)\) is the support of \(M\).

Proof

omitted for now