Ancestor ideals of vector spaces of forms, and level algebras

dc.creatorIarrobino, Anthony
dc.date2003-07-21
dc.date.accessioned2026-07-07T06:32:56Z
dc.date.available2026-07-07T06:32:56Z
dc.descriptionLet R be the polynomial ring in r variables over a field k, with maximal ideal M and let V denote a vector subspace of the space of degree-j homogeneous elements of R. We study three related algebras determined by V. The first is the ``ancestor algebra'' whose defining ideal is the largest graded ideal whose intersection with M^j is the ideal (V). The second is the ``level algebra'', whose defining ideal L(V) is the largest graded ideal of R such that the degree-j component is V; and third is the algebra R/(V). When r=2, we determine the possible Hilbert functions H for each of these algebras, and as well the dimension of each Hilbert function stratum. We characterize the graded Betti numbers of these algebras in terms of certain partitions depending only on H, and give the codimension of each stratum in terms of invariants of the partitions. When r=2 and k is algebraically closed the Hilbert function strata for each of the three algebras satisfy a frontier property that the closure of a stratum is the union of more special strata. The family G(H) of all graded quotients of R having the given Hilbert function is a natural desingularization of this closure.
dc.description41 pages, LateX file, to appear Journal of Algebra
dc.identifierhttps://arxiv.org/abs/math/0307281
dc.identifierhttp://arxiv.org/abs/math/0307281
dc.identifierJ. Algebra 272 (2004), no. 2, 530--580
dc.identifier.urihttp://salesiana.dossiersoluciones.com/handle/123456789/99025
dc.subjectCommutative Algebra
dc.subjectAlgebraic Geometry
dc.subject13D40, 14C05
dc.titleAncestor ideals of vector spaces of forms, and level algebras
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