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Paper   IPM / M / 18172
School of Mathematics
  Title:   Computing finite and infinite free resolutions with Pommaret-like bases
  Author(s):  Amir Hashemi (Joint with M. Orth and W. M. Seiler)
  Status:   Published
  Journal: J. Symb. Comput.
  Vol.:  131
  Year:  2025
  Pages:   #102454
  Supported by:  IPM
  Abstract:
Free resolutions are an important tool in algebraic geometry for the structural analysis of modules over polynomial rings and their quotient rings. Minimal free resolutions are unique up to isomorphism and induce homological invariants in the form of Betti numbers. It is known that Pommaret bases of ideals in the polynomial ring induce finite free resolutions and that the Castelnuovo-Mumford regularity and projective dimension can be read off directly from the Pommaret basis. In this article, we generalize this construction to Pommaret-like bases, which are generally smaller. We apply Pommaret-like bases also to infinite resolutions over quotient rings. Over Clementsâ??Lindstr�¶m rings, we derive bases for the free modules in the resolution using only the Pommaret-like basis. Finally, restricting to monomial ideals in a non-quotient polynomial ring, we derive an explicit formula for the differential of the induced resolution.

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