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Comparing Castelnuovo-Mumford regularity and extended degree: the borderline cases

Uwe Nagel
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Abstract

Castelnuovo-Mumford regularity and any extended degree function can be thought of as complexity measures for the structure of finitely generated graded modules. A recent result of Doering, Gunston, Vasconcelos shows that both can be compared in case of a graded algebra. We extend this result to modules and analyze when the estimate is in fact an equality. A complete classification is obtained if we choose as extended degree the homological or the smallest extended degree. The corresponding algebras are characterized in three ways: by relations among the algebra generators, by using generic initial ideals, and by their Hilbert series.

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Uwe Nagel. 2003-11-28. Comparing Castelnuovo-Mumford regularity and extended degree: the borderline cases. https://arxiv.org/abs/math/0311534

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