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section functor (Definition)

Essential data

Let us consider an Abelian category $\mathcal{C}$ which is locally small and a dense subcategory $\mathcal{A}$ of $\mathcal{C}$ , with $T: \mathcal{C} \to \mathcal{C}/\mathcal{A}$ being the canonical functor. Moreover, let us assume that $T$ has a right adjoint denoted by $S$ such that one has the following functorial isomorphism, or natural equivalence:

$$Hom_{\mathcal{C}}(X, S(Y)) \cong Hom_{\mathcal{C} / \mathcal{A}}$$ .

Definition 1.1   The right adjoint functor $$S: \mathcal{C}/ \mathcal{A} \to \mathcal{C}$$ of $T$ - which is specified by the essential data above- is called a section functor.

Note: the category $\mathcal{A}$ is defined as a localizing subcategory.




"section functor" is owned by bci1.
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Also defines:  localizing subcategory
Keywords:  section functor, adjoint functor, localization
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Cross-references: category, natural equivalence, isomorphism, right adjoint, functor, canonical, dense subcategory, locally small, abelian category
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This is version 9 of section functor, born on 2008-10-03, modified 2009-04-05.
Object id is 11130, canonical name is SectionFunctor.
Accessed 823 times total.

Classification:
AMS MSC18-00 (Category theory; homological algebra :: General reference works )
 18E05 (Category theory; homological algebra :: Abelian categories :: Preadditive, additive categories)

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