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Directed graphs naturally model systems with asymmetric, ordered relationships, essential to applications in biology, transportation, social networks, and visual understanding. Generating such graphs enables tasks such as simulation, data…

Machine Learning · Computer Science 2026-02-20 Alba Carballo-Castro , Manuel Madeira , Yiming Qin , Dorina Thanou , Pascal Frossard

We present an algorithm that produces the classification list of smooth Fano d-polytopes for any given d. The input of the algorithm is a single number, namely the positive integer d. The algorithm has been used to classify smooth Fano…

Combinatorics · Mathematics 2007-05-23 Mikkel Øbro

We apply the combinatorial theory of spherical varieties to characterize the momentum polytopes of polarized projective spherical varieties. This enables us to derive a classification of these varieties, without specifying the open orbit,…

Algebraic Geometry · Mathematics 2020-04-16 Stéphanie Cupit-Foutou , Guido Pezzini , Bart Van Steirteghem

We give a necessary and sufficient condition for the nonsingular projective toric variety associated to a finite simple graph to be Fano or weak Fano in terms of the graph.

Algebraic Geometry · Mathematics 2016-05-17 Yusuke Suyama

We study two simplicial complexes arising from a directed graph $G = (V, E)$ with two chosen vertices $s$ and $t$: the *path-free complex*, consisting of all subsets $F \subseteq E$ that contain no path from $s$ to $t$, and the…

Combinatorics · Mathematics 2025-06-12 Darij Grinberg , Lukas Katthän , Joel Brewster Lewis

We associate root polytopes to directed graphs and study them by using ribbon structures. Most attention is paid to what we call the semi-balanced case, i.e., when each cycle has the same number of edges pointing in the two directions.…

Combinatorics · Mathematics 2024-08-16 Tamás Kálmán , Lilla Tóthmérész

To directed graphs with unique sink and source we associate a noncommutative associative alsgebra and a polynomial over this algebra. Edges of the graph correspond to pseudo-roots of the polynomial. We give a sufficient condition when…

Quantum Algebra · Mathematics 2009-11-11 Israel Gelfand , Sergei Gelfand , Vladimir Retakh , Robert Lee Wilson

We introduce and study analogues of expander and hyperfinite graph sequences in the context of directed acyclic graphs, which we call "extender" and "hypershallow" graph sequences, respectively. Our main result is a probabilistic…

Combinatorics · Mathematics 2023-06-22 Endre Csóka , Łukasz Grabowski

Starting from any finite simple graph, one can build a reflexive polytope known as a symmetric edge polytope. The first goal of this paper is to show that symmetric edge polytopes are intrinsically matroidal objects: more precisely, we…

Combinatorics · Mathematics 2023-07-12 Alessio D'Alì , Martina Juhnke-Kubitzke , Melissa Koch

In this work we establish that finite directed graphs give rise to semiflows on the power set of their nodes. We analyze the topological dynamics for semiflows on finite directed graphs by characterizing Morse decompositions, recurrence…

Dynamical Systems · Mathematics 2020-05-29 José Ayala , Wolfgang Kliemann

This paper focuses on certain finite dimensional point derivations for the non-selfadjoint operator algebras corresponding to directed graphs. We begin by analyzing the derivations corresponding to full matrix representations of the tensor…

Operator Algebras · Mathematics 2009-11-12 Benton L. Duncan

A directed graph is set-homogeneous if, whenever U and V are isomorphic finite subdigraphs, there is an automorphism g of the digraph with U^g=V. Here, extending work of Lachlan on finite homogeneous digraphs, we classify finite…

Combinatorics · Mathematics 2010-11-19 Robert Gray , Dugald Macpherson , Cheryl E. Praeger , Gordon F. Royle

We construct Fano threefolds with very ample anti-canonical bundle and Picard rank greater than one from cracked polytopes - polytopes whose intersection with a complete fan forms a set of unimodular polytopes - using Laurent inversion; a…

Algebraic Geometry · Mathematics 2019-07-30 Thomas Prince

The classification of toric Fano manifolds with large Picard number corresponds to the classification of smooth Fano polytopes with large number of vertices. A smooth Fano polytope is a polytope that contains the origin in its interior such…

Algebraic Geometry · Mathematics 2015-08-11 Benjamin Assarf , Benjamin Nill

The fractional perfect b-matching polytope of an undirected graph G is the polytope of all assignments of nonnegative real numbers to the edges of G such that the sum of the numbers over all edges incident to any vertex v is a prescribed…

Combinatorics · Mathematics 2013-01-31 Roger E. Behrend

We define a subclass of separated graphs, the class of adaptable separated graphs, and study their associated monoids. We show that these monoids are primely generated conical refinement monoids, and we explicitly determine their associated…

Rings and Algebras · Mathematics 2019-04-10 P. Ara , J. Bosa , E. Pardo

We survey recent results on the existence of K\"ahler-Einstein metrics on certain smoothable Fano varieties, focusing on the importance of such metrics in the construction of compact algebraic moduli spaces of K-polystable Fano varieties.…

Algebraic Geometry · Mathematics 2017-05-02 Cristiano Spotti

In this paper, we construct directed strongly regular graphs with new parameters by using partial sum families with local rings. 16 families of new directed strongly regular graphs are obtained and the uniform partial sum families are…

Combinatorics · Mathematics 2020-02-25 Jingkun Zhou , Zhiwen He , Zhao Chai

Let $P$ be a simplicial smooth Fano polytope. We provide a concrete unimodular triangulation of $P$. We prove that the delta-vector of a simplicial smooth Fano polytope is unimodal and we give upper and lower bound for the volume of…

Combinatorics · Mathematics 2026-05-05 Gábor Hegedüs

This paper studies infinite graphs produced from a natural unfolding operation applied to finite graphs. Graphs produced via such operations are of finite degree and automatic over the unary alphabet (that is, they can be described by…

Logic · Mathematics 2008-09-22 Bakhadyr Khoussainov , Jiamou Liu , Mia Minnes