Freyd realizations of the two coherent-defect presentations #
The restricted contravariant and covariant Yoneda embeddings are fully faithful and have projective values. Their right-Freyd cokernel realizations are therefore fully faithful. This packages the projective-resolution lifting and homotopy-independence used in the morphism part of Auslander's coherent duality.
Restricted contravariant Yoneda is full on all finitely generated modules.
Restricted contravariant Yoneda is faithful on all finitely generated modules.
Every finite contravariant functor is an epimorphic image of a restricted representable of a finitely generated module.
The right-Freyd realization of contravariant representable presentations.
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Every finite contravariant functor has a restricted-representable presentation, and right homotopy is exactly equality on its cokernel.
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The right-Freyd realization of covariant representable presentations.
The representing module variable is opposite because Hom(X,−) is
contravariant in X.
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Every finite covariant functor is an epimorphic image of a restricted covariant representable of an object of the opposite module category.
Every finite covariant functor has a restricted-corepresentable presentation, modulo right homotopy.
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The contravariant Freyd realization restricted to epimorphic presentations.
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Epimorphic Freyd presentations realized as exact contravariant defects.
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Exact contravariant defects are the cokernel realizations of epimorphic presentations.
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The covariant Freyd realization restricted to epimorphic presentations in the opposite module category.
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Epimorphic opposite-Freyd presentations realized as exact covariant defects.
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Exact covariant defects are the cokernel realizations of epimorphic presentations in the opposite module category.
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Auslander's anti-equivalence on the exact-defect subcategories, realized by projective presentations and kernel reversal.