Gunnar Floystad
The cone of Betti diagrams of bigraded artinian modules of codimension two.
Ср, 01/20/2010 - 16:01 — SomNambulAuthors: Gunnar Floystad, Mats Boij
Subjects: Commutative Algebra
AbstractWe describe the positive cone generated by bigraded Betti diagrams of
artinian modules of codimension two, whose resolutions become pure of a given
type when taking total degrees. If the differences of these total degrees, p
and q, are relatively prime, the extremal rays are parametrised by order ideals
in N^2 contained in the region px + qy < (p-1)(q-1). We also consider some
examples concerning artinian modules of codimension three.The linear space of Betti diagrams of multigraded artinian modules.
Ср, 01/20/2010 - 16:01 — SomNambulAuthors: Gunnar Floystad
Subjects: Commutative Algebra
AbstractWe study the linear space generated by the multigraded Betti diagrams of
Z^n-graded artinian modules of codimension n whose resolutions become pure of a
given type when taking total degrees. We show that the multigraded Betti
diagram of the equivariant resolution constructed by D.Eisenbud, J.Weyman, and
the author, and all its twists, form a basis for this linear space.Artin-Schelter regular algebras of dimension five.
Пнд, 11/30/2009 - 16:01 — SomNambulAuthors: Gunnar Floystad, Jon Eivind Vatne
Subjects: Rings and Algebras
AbstractWe show that there are exactly three types of Hilbert series of
Artin-Schelter regular algebras of dimension five with two generators. One of
these cases (the most extreme) may not be realized by an enveloping algebra of
a graded Lie algebra. This is a new phenomenon compared to lower dimensions,
where all resolution types may be realized by such enveloping algebras.
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