Monad (homological algebra)

In homological algebra, a monad is a 3-term complex

A → B → C
Not to be confused with Monad (category theory).

of objects in some abelian category whose middle term B is projective, whose first map A → B is injective, and whose second map B → C is surjective. Equivalently, a monad is a projective object together with a 3-step filtration B ⊃ ker(B → C) ⊃ im(A → B). In practice A, B, and C are often vector bundles over some space, and there are several minor extra conditions that some authors add to the definition. Monads were introduced by Horrocks (1964, p.698).

See also

References
  • Barth, Wolf; Hulek, Klaus (1978), "Monads and moduli of vector bundles", Manuscripta Mathematica, 25 (4): 323–347, doi:10.1007/BF01168047, ISSN 0025-2611, MR 0509589, Zbl 0395.14007
  • Horrocks, G. (1964), "Vector bundles on the punctured spectrum of a local ring", Proceedings of the London Mathematical Society, Third Series, 14 (4): 689–713, doi:10.1112/plms/s3-14.4.689, ISSN 0024-6115, MR 0169877, Zbl 0126.16801


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