NORTHEASTERN UNIVERSITY
MATHEMATICS DEPARTMENT
 
Geometry-Algebra-Singularities-Combinatorics 
Seminar
 
 
Zero-dimensional schemes, Gorenstein algebras and simplicial complexes 
 
 

Mats Boij

(KTH, Stockholm )
 
 

Northeastern University

509 Lake Hall

1:30 p.m., Monday, September 25, 2000

 
 
Abstract:   Given a graded algebra R over a field k, we look at the graded Gorenstein Artin quotients A of R. In particular, when R is the homogeneous coordinate ring of a zero-dimensional scheme in projective space, we study under what conditions there are Gorenstein Artin quotients of R with Hilbert function equal to the Hilbert function of R in all degrees less than or equal to half the socle degree. Similar results have been obtained by Iarrobino and Kanev~\cite{Iarrobino-Kanev} and by Cho and Iarrobino~\cite{Cho-Iarrobino} using inverse systems.

If \Delta is a Cohen-Macaulay simplicial complex and k[\Delta] the corresponding Stanley-Reisner ring, we can take the quotient of k[\Delta] by a regular sequence to get the coordinate ring of a zero-dimensional scheme consisting of n distinct points in projective space. We make some remarks on how this observation can be used to give interesting examples of zero-dimensional schemes. In particular, we get arithmetically Gorenstein subschemes if the complex is Gorenstein, e.g. a simplicial polytope or a simplicial sphere. We also get results about generalized stick figures (cf. Geramita and Migliore~\cite{Geramita-Migliore}).

 
Home Web page:  Alexandru I. Suciu  Created: Sept 10, 2000   
Maintained by:  Carol Chang  URL: http://www.math.neu.edu/~GASC/gas/boij.html