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We classify the finite connected simple graphs whose edge rings are strongly Koszul. From the classification, it follows that if the edge ring is strongly Koszul, then its toric ideal possesses a quadratic Gr\"obner basis.

Commutative Algebra · Mathematics 2016-02-02 Takayuki Hibi , Kazunori Matsuda , Hidefumi Ohsugi

We characterise those objects in the derived category of a scheme which are a sheaf supported on a closed subscheme in terms of Koszul complexes. This is applied to generalize to arbitrary schemes the fully faithfullness criteria of an…

Algebraic Geometry · Mathematics 2014-02-26 Fernando Sancho de Salas

For a projective hypersurface $Z$ with isolated singularities, we generalize some well-known assertions in the nonsingular case due to Griffiths, Scherk, Steenbrink, Varchenko, and others about the relations between the Steenbrink spectrum,…

Algebraic Geometry · Mathematics 2024-03-11 Alexandru Dimca , Morihiko Saito

Let S=K[x_1,...,x_n] be a polynomial ring over a field K and I a homogeneous ideal in S generated by a regular sequence f_1,f_2,...,f_k of homogeneous forms of degree d. We study a generalization of a result of Conca, Herzog, Trung, and…

Commutative Algebra · Mathematics 2013-08-01 Neeraj Kumar

We give necessary and sufficient conditions for strong Koszulness of toric rings associated with the stable set polytope of graphs.

Commutative Algebra · Mathematics 2013-09-17 Kazunori Matsuda

In a polynomial ring $R$ with $n$ variables, for every homogeneous ideal $I$ and for every $p\leq n$ we consider the Koszul homology $H_i(p,R/I)$ with respect to a sequence of $p$ of generic linear forms and define the Koszul-Betti number…

Commutative Algebra · Mathematics 2007-05-23 Aldo Conca

We prove Koszulity of the homology of the of moduli spaces of stable n-pointed curves of genus zero $\overline{M}_{0,n}$ for $n=5$, using its presentation due to Keel and the Priddy criterion of Koszulity. For $n=6 $ we establish that…

Rings and Algebras · Mathematics 2017-11-22 Natalia Iyudu

We define a local homomorphism $(Q,k)\to (R,\ell)$ to be Koszul if its derived fiber $R \otimes^{\mathsf{L}}_Q k$ is formal, and if $\operatorname{Tor}^Q(R,k)$ is Koszul in the classical sense. This recovers the classical definition when…

Commutative Algebra · Mathematics 2025-04-02 Benjamin Briggs , James C. Cameron , Janina C. Letz , Josh Pollitz

Let $G$ be a simple, simply connected algebraic group over an algebraically closed field of positive characteristic $p$. In recent work, the authors have studied a graded analogue of the category of rational $G$-modules. These gradings are…

Representation Theory · Mathematics 2013-05-28 Brian J. Parshall , Leonard L. Scott

Let $(R,\mathfrak m, \mathsf k)$ be a complete intersection local ring, $K$ be the Koszul complex on a minimal set of generators of $\mathfrak m$, and $A=H(K)$ be its homology algebra. We establish exact sequences involving direct sums of…

Commutative Algebra · Mathematics 2024-04-04 Van C. Nguyen , Oana Veliche

We show that any upper finite or essentially finite highest weight category where the standard objects have linear projective resolutions and the costandard objects have linear injective resolutions is Koszul. This extends the result of…

Representation Theory · Mathematics 2025-06-12 Thorsten Heidersdorf , Jonas Nehme , Catharina Stroppel

We prove regularity bounds for Koszul cycles holding for every ideal of dimension at most 1 in a polynomial ring. We generalize the lower bound for the Green-Lazarsfeld index of Veronese rings we proved in arXiv:0902.2431 to the…

Commutative Algebra · Mathematics 2010-09-08 Winfreid Bruns , Aldo Conca , Tim Römer

We study a properly convex real projective manifold with (possibly empty) compact, strictly convex boundary, and which consists of a compact part plus finitely many convex ends. We extend a theorem of Koszul which asserts that for a compact…

Geometric Topology · Mathematics 2018-03-28 Daryl Cooper , Darren Long , Stephan Tillmann

In this paper, we introduce the point-exact condition for a Koszul algebra $A$, which is useful for characterizing the (G1) condition of $A$ in the sense of Mori. Let $B = A/(f)$, where $f \in A_2$ is a regular normal element. We show that…

Rings and Algebras · Mathematics 2026-03-17 Haigang Hu , Wenchao Wu , Yu Ye

We discuss various applications of a uniform vanishing result for the graded components of the finite length Koszul module associated to a subspace in the second wedge product of a vector space. Previously Koszul modules of finite length…

Algebraic Geometry · Mathematics 2023-12-11 Marian Aprodu , Gavril Farkas , Claudiu Raicu , Jerzy Weyman

A cut ideal of a graph was introduced by Sturmfels and Sullivant. In this paper, we give a necessary and sufficient condition for toric rings associated to the cut ideal to be Strongly Koszul.

Commutative Algebra · Mathematics 2019-07-24 Kazuki Shibata

Koszul modules and their associated resonance schemes are objects appearing in a variety of contexts in algebraic geometry, topology, and combinatorics. We present a proof of an effective version of the Chen ranks conjecture describing the…

Algebraic Geometry · Mathematics 2025-12-12 Marian Aprodu , Gavril Farkas , Claudiu Raicu , Alexander I. Suciu

In this paper we study monomial cycles in Koszul homology over a monomial ring. The main result is that a monomial cycle is a boundary precisely when the monomial representing that cycle is contained in an ideal we introduce called the…

Commutative Algebra · Mathematics 2024-09-13 Jacob Zoromski

Cassidy, Phan and Shelton associate to any regular cell complex X a quadratic K-algebra R(X). They give a combinatorial solution to the question of when this algebra is Koszul. The algebra R(X) is a combinatorial invariant but not a…

Rings and Algebras · Mathematics 2009-11-16 Hal Sadofsky , Brad Shelton

Koszul and homogeneous Koszul algebras were defined by Priddy in \cite{Priddy1970}. There exist some relations between these algebras and the skew PBW extensions introduced in \cite{LezamaGallego}. In this paper we give conditions to…

Rings and Algebras · Mathematics 2016-11-15 Héctor Suárez , Armando Reyes