On toric varieties which are almost set-theoretic complete intersections

We describe a class of affine toric varieties V that are set-theoretically minimally defined by binomial equations over fields of any characteristic.     

The equations of almost complete intersections

In this paper we inject four Hilbert functions in the determination of the defining equations of the Rees algebra of almost complete intersections of finite co-length. Because three of the corresponding modules are Artinian, some of these relationships are very effective, with the novel approach opening up tracks to the determination of the equations and also to processes of going from homologically defined sets of equations to higher degrees ones. While not specifically directed towards the extraction of elimination equations, it will show how some of these arise naturally.     

A remark on almost complete intersections

Let k be a perfect field and S the quotient ring of a polynomial ring k[X₁,...,X_t] with respect to a prime ideal. Let I be a prime ideal of S such that R=S/I is an almost complete intersection. Then, in his paper [2], Matsuoka proves that the homological dimension of the differential module _R/Kis infinite under the assumption that R is Cohen-Macaulay and I² is a primary idea]. In this paper we prove that the result is valid without the above assumption.     

On almost revlex ideals with Hilbert function of complete intersections

Ricerche di Matematica - In this paper, we investigate the behavior of almost reverse lexicographic ideals with the Hilbert function of a complete intersection. More precisely, over a field K, we...     

Resolutions of monomial almost complete intersections and generalizations

Let S=K[x₁,…,x_n] be a polynomial ring over a field kand let / be a monomial ideal of S. The main result of this paper is an explicit minimal resolution of kover R= S/Iwhen / is a monomial almost complete intersection ideal of S. We also compute an upper bound on the multigraded resolution of k over a generalization of monomial almost complete intersection ring.     

On Landsberg's criterion for complete intersections

Partially supported by ISF grant MSC000     

On the regularity of products and intersections of complete intersections

This paper proves the formulae

for arbitrary monomial complete intersections and , and provides examples showing that these inequalities do not hold for general complete intersections.

     

On complete intersections with trivial canonical class

We prove birational boundedness results on complete intersections with trivial canonical class of base point free divisors in (some version of) Fano varieties. Our results imply in particular that Batyrev–Borisov toric construction produces only a bounded set of Hodge numbers in any given dimension, even as the codimension is allowed to grow.     

On the homotopy type of complete intersections

The homotopy classification problem for complete intersections is settled when the complex dimension is larger than the total degree.     

Symmetric complete intersections

We consider complete intersection ideals in a polynomial ring over a field of characteristic zero that are stable under the action of the symmetric group permuting the variables. We determine the possible representation types for these ideals and describe formulas for the graded characters of the corresponding quotient rings.     

On extensive games and almost complete information

Our main result for finite games in extensive form is that strict determinacy for a playeri in a completely inflated game structure implies almost complete information for playeri, even if we allow for certain type of overlapping for information sets.     

On support varieties for modules over complete intersections

Let be a complete intersection of codimension , and let be the algebraic closure of . We show that every homogeneous algebraic subset of is the cohomological support variety of an -module, and that the projective variety of a complete indecomposable maximal Cohen-Macaulay -module is connected.

     

On modules of finite projective dimension over complete intersections

Recently Avramov and Miller proved that over a local complete intersection ring in characteristic 0$">, a finitely generated module has finite projective dimension if for some 0$"> and for some 0$">, being the frobenius map repeated times. They used the notion of ``complexity' and several related theorems. Here we offer a very simple proof of the above theorem without using ``complexity' at all.