20 research outputs found
Shedding vertices and Ass-decomposable monomial ideals
The shedding vertices of simplicial complexes are studied from an algebraic
point of view. Based on this perspective, we introduce the class of
ass-decomposable monomial ideals which is a generalization of the class of
Stanley-Reisner ideals of vertex decomposable simplicial complexes. The
recursive structure of ass-decomposable monomial ideals allows us to find a
simple formula for the depth, and in squarefree case, an upper bound for the
regularity of such ideals.Comment: 13 page
The saturation number of monomial ideals
Let be the polynomial ring over a field
and be the irredundant maximal
ideal of . For an ideal , let be the minimum
number for which .
In this paper, we compute the saturation number of irreducible monomial ideals
and their powers. We apply this result to find the saturation number of the
ordinary powers and symbolic powers of some families of monomial ideals in
terms of the saturation number of irreducible components appearing in an
irreducible decomposition of these ideals. Moreover, we give an explicit
formula for the saturation number of monomial ideals in two variables
Gr\"obner basis and Krull dimension of Lov\'asz-Saks-Sherijver ideal associated to a tree
Let be a field and be a positive integer. Let be a simple graph, where . If is a polynomial ring, then the graded ideal is called the Lov\'{a}sz-Saks-Schrijver
ideal, LSS-ideal for short, of with respect to . In the
present paper, we compute a Gr\"obner basis of this ideal with respect to
lexicographic ordering induced by when
is a tree. As a result, we show that it is independent of the choice
of the ground field and compute the Hilbert series of
. Finally, we present concrete combinatorial formulas to
obtain the Krull dimension of as well as lower and upper
bounds for Krull dimension.Comment: 23 pages, 1 figur
Monomial ideals with 3-linear resolutions
In this paper, we study Cstelnuovo-Mumford regularity of square-free monomial
ideals generated in degree 3. We define some operations on the clutters
associated to such ideals and prove that the regularity is conserved under
these operations. We apply the operations to introduce some classes of ideals
with linear resolutions and also show that any clutter corresponding to a
triangulation of the sphere does not have linear resolution while any proper
sub-clutter of it has a linear resolution.Comment: 11 page