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The emergence of Boij-S\"oderberg theory has given rise to new connections between combinatorics and commutative algebra. Herzog, Sharifan, and Varbaro recently showed that every Betti diagram of an ideal with a k-linear minimal resolution…

Combinatorics · Mathematics 2016-01-20 Alexander Engström , Matthew T. Stamps

We study the expected behavior of the Betti numbers of arrangements of the zeros of random (distributed according to the Kostlan distribution) polynomials in $\mathbb{R}\mathrm{P}^n$. Using a random spectral sequence, we prove an…

Algebraic Geometry · Mathematics 2022-06-09 Saugata Basu , Antonio Lerario , Abhiram Natarajan

In this thesis we investigate certain types of monomial ideals of polynomial rings over fields. We are interested in minimal free resolutions of these ideals (or equivalently the quotients of the polynomial ring by the ideals) considered as…

Commutative Algebra · Mathematics 2007-05-23 Sean Jacques

Let $\mathcal{D}$ be a weighted oriented graph and $I(\mathcal{D})$ be its edge ideal. In this paper, we investigate the Betti numbers of $I(\mathcal{D})$ via upper-Koszul simplicial complexes, Betti splittings and the mapping cone…

Commutative Algebra · Mathematics 2020-09-24 Beata Casiday , Selvi Kara

We study mathematical expectations of Betti numbers of configuration spaces of planar linkages, viewing the lengths of the bars of the linkage as random variables. Our main result gives an explicit asymptotic formulae for these mathematical…

Algebraic Topology · Mathematics 2007-05-23 Michael Farber , Thomas Kappeler

We present two new problems on lower bounds for resolution Betti numbers of monomial ideals generated in a fixed degree. The first concerns any such ideal and bounds the total Betti numbers, while the second concerns ideals that are…

Commutative Algebra · Mathematics 2007-12-18 Uwe Nagel , Victor Reiner

The total Betti numbers of the toric ideal of a simple graph are, in general, highly sensitive to any small change of the graph. In this paper we look at some combinatorial operations that cause total Betti numbers to change in predictable…

Commutative Algebra · Mathematics 2024-04-30 Giuseppe Favacchio

We compute one of the distinguished extremal Betti number of the binomial edge ideal of a block graph, and classify all block graphs admitting precisely one extremal Betti number.

Commutative Algebra · Mathematics 2018-02-19 Juergen Herzog , Giancarlo Rinaldo

In this article bipartite planar graphs St_r are investigated, r the number of their plane regions. Bounds for the graded Betti numbers and the projective dimension of the quotient ring associated to such graphs are discussed. We prove that…

Commutative Algebra · Mathematics 2024-04-01 Maurizio Imbesi , Monica La Barbiera

We study the Betti numbers of binomial edge ideal associated to some classes of graphs with large Castelnuovo-Mumford regularity. As an application we give several lower bounds of the Castelnuovo-Mumford regularity of arbitrary graphs…

Commutative Algebra · Mathematics 2013-10-16 Zohaib Zahid , Sohail Zafar

We study the Betti tables of reducible algebraic curves with a focus on connected line arrangements and provide a general formula for computing the quadratic strand of the Betti table for line arrangements that satisfy certain hypotheses.…

Algebraic Geometry · Mathematics 2015-07-17 David J. Bruce , Pin-Hung Kao , Evan D. Nash , Ben Perez , Peter Vermeire

We compute the multigraded Betti numbers of edge ideals for weighted oriented crown graphs using a novel approach. This approach, which we still call the \emph{induced subgraph approach}, originates from our prior work on computing Betti…

Commutative Algebra · Mathematics 2025-05-13 Zexin Wang , Dancheng Lu

The expected value for the weighted crossing number of a randomly weighted graph is studied. A variation of the Crossing Lemma for expectations is proved. We focus on the case where the edge-weights are independent random variables that are…

Combinatorics · Mathematics 2010-12-14 Bojan Mohar , Tamon Stephen

Let $G$ be the circulant graph $C_n(S)$ with $S \subseteq \{1, 2, \dots, \lfloor \frac{n}{2} \rfloor\}$, and let $I(G)$ denote the edge ideal in the polynomial ring $R=\mathbb{K}[x_0, x_1, \dots, x_{n-1}]$ over a field $\mathbb{K}$. In this…

Combinatorics · Mathematics 2025-10-06 Sonica Anand , Amit Roy

We associate a sequence of positive integers, termed the type sequence, with a cochordal graph. Using this type sequence, we compute all graded Betti numbers of its edge ideal. We then classify all positive integer $n$ such that the zero…

Commutative Algebra · Mathematics 2024-11-13 Le Xuan Dung , Thanh Vu

We study homological properties of random quadratic monomial ideals in a polynomial ring $R = {\mathbb K}[x_1, \dots x_n]$, utilizing methods from the Erd\"{o}s-R\'{e}nyi model of random graphs. Here for a graph $G \sim G(n, p)$ we consider…

Commutative Algebra · Mathematics 2023-08-16 Anton Dochtermann , Andrew Newman

We apply some basic notions from combinatorial topology to establish various algebraic properties of edge ideals of graphs and more general Stanley-Reisner rings. In this way we provide new short proofs of some theorems from the literature…

Combinatorics · Mathematics 2008-10-23 Anton Dochtermann , Alexander Engstrom

In this paper, we obtain a combinatorial formula for computing the Betti numbers in the linear strand of edge ideals of bipartite Kneser graphs. We deduce lower and upper bounds for regularity of powers of edge ideals of these graphs in…

Commutative Algebra · Mathematics 2021-05-14 Ajay Kumar , Pavinder Singh , Rohit Verma

We introduce a novel approach named the {\it induced-subgraph approach} for investigating the Betti numbers of normal edge rings. Utilizing this approach, we compute all the multi-graded Betti numbers of the edge rings associated with…

Commutative Algebra · Mathematics 2025-05-02 Zexin Wang , Dancheng Lu

We compute the graded Betti numbers for the toric ideal of a family of graphs constructed by adjoining a cycle to a complete bipartite graph. The key observation is that this family admits an initial ideal which has linear quotients. As a…

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