nLab perfect chain complex



Homological algebra

homological algebra

(also nonabelian homological algebra)



Basic definitions

Stable homotopy theory notions



diagram chasing

Schanuel's lemma

Homology theories


Compact objects



A perfect complex over a commutative ring AA is a perfect module over the Eilenberg-Mac Lane spectrum H(A)H(A). Under the stable Dold-Kan correspondence, perfect complexes correspond to bounded chain complexes of finitely generated projective modules.

Viewing commutative rings as affine schemes, this definition generalizes to arbitrary stacks. In this generality, perfect modules still coincide with the dualizable objects, but not always with the compact objects. The latter does hold for quasi-compact quasi-separated schemes by work of Thomason, Neeman, Bondal-Van den Bergh.


Relation to compact objects


Let AA be a commutative ring and let D(A)D(A) denote the derived category of AA-modules. A chain complex M M_\bullet of AA-modules is perfect if and only if it is a compact object of D(A)D(A).

For instance (Stacks Project, 07LT).

Perfect complexes on a ringed space

Let (X,𝒪 X)(X, \mathcal{O}_X) be a ringed space. A chain complex of 𝒪 X\mathcal{O}_X-modules is called perfect if it is locally quasi-isomorphic to a bounded complex of free? 𝒪 X\mathcal{O}_X-modules of finite type.

Let D(Mod(𝒪 X))D(Mod(\mathcal{O}_X)) be the derived category of 𝒪 X\mathcal{O}_X-modules. Let Pf(X)D(Mod(𝒪 X))Pf(X) \subset D(Mod(\mathcal{O}_X)) denote the full subcategory of perfect complexes. This is a triangulated subcategory, see triangulated categories of sheaves.

finite objects:

geometrymonoidal category theorycategory theory
perfect module(fully-)dualizable objectcompact object


Last revised on January 2, 2016 at 22:43:50. See the history of this page for a list of all contributions to it.