On the Arithmetical Rank of the Edge Ideals of Some Graphs

2012 ◽  
Vol 19 (spec01) ◽  
pp. 797-806 ◽  
Author(s):  
Fatemeh Mohammadi ◽  
Dariush Kiani

In this paper, we compute the projective dimension of the edge ideals of graphs consisting of some cycles and lines which are joint in a common vertex. Moreover, we show that for such graphs, the arithmetical rank equals the projective dimension. As an application, we can compute the arithmetical rank for some homogenous monomial ideals.

2021 ◽  
Vol 28 (02) ◽  
pp. 253-268
Author(s):  
Hong Wang ◽  
Guangjun Zhu ◽  
Li Xu ◽  
Jiaqi Zhang

We provide some exact formulas for the projective dimension and regularity of edge ideals associated to some vertex-weighted oriented cyclic graphs with a common vertex or edge. These formulas are functions in the weight of the vertices, and the numbers of edges and cycles. Some examples show that these formulas are related to direction selection and the assumption that [Formula: see text] for any vertex [Formula: see text] cannot be dropped.


2012 ◽  
Vol 11 (02) ◽  
pp. 1250039 ◽  
Author(s):  
MARGHERITA BARILE ◽  
DARIUSH KIANI ◽  
FATEMEH MOHAMMADI ◽  
SIAMAK YASSEMI

We show that for the edge ideals of the graphs consisting of one cycle or two cycles of any length connected through a vertex, the arithmetical rank equals the projective dimension of the corresponding quotient ring.


2017 ◽  
Vol 10 (03) ◽  
pp. 1750061
Author(s):  
Somayeh Moradi

In this paper, we study the regularity and the projective dimension of the Stanley–Reisner ring of a [Formula: see text]-decomposable simplicial complex and explain these invariants with a recursive formula. To this aim, the graded Betti numbers of decomposable monomial ideals which is the dual concept for [Formula: see text]-decomposable simplicial complexes are studied and an inductive formula for the Betti numbers is given. As a corollary, for a shellable simplicial complex [Formula: see text], a formula for the regularity of the Stanley–Reisner ring of [Formula: see text] is presented. Finally, for a chordal clutter [Formula: see text], an upper bound for [Formula: see text] is given in terms of the regularities of edge ideals of some chordal clutters which are minors of [Formula: see text].


2017 ◽  
Vol 45 (12) ◽  
pp. 5407-5419
Author(s):  
Margherita Barile ◽  
Antonio Macchia

2019 ◽  
Vol 18 (12) ◽  
pp. 1950224
Author(s):  
Somayeh Bandari ◽  
Raheleh Jafari

We introduce the concept of monomial ideals with stable projective dimension, as a generalization of the Cohen–Macaulay property. Indeed, we study the class of monomial ideals [Formula: see text], whose projective dimension is stable under monomial localizations at monomial prime ideals [Formula: see text], with [Formula: see text]. We study the relations between this property and other sorts of Cohen–Macaulayness. Finally, we characterize some classes of polymatroidal ideals with stable projective dimension.


1988 ◽  
Vol 112 (1) ◽  
pp. 86-89 ◽  
Author(s):  
Gennady Lyubeznik

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