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By studying the weak closure of multidimensional off-diagonal self-joinings we provide a criterion for non-isomorphism of a flow with its inverse, hence the non-reversibility of a flow. This is applied to special flows over rigid…

Dynamical Systems · Mathematics 2014-05-13 K. Fraczek , J. Kulaga , M. Lemanczyk

We experimentally investigate flow of quasi two-dimensional disordered foams in Couette geometries, both for foams squeezed below a top plate and for freely floating foams. With the top-plate, the flows are strongly localized and rate…

Soft Condensed Matter · Physics 2015-05-18 G. Katgert , B. P. Tighe , M. E. Möbius , M. van Hecke

Given a graph $G$, the number of nowhere-zero $\ZZ_q$-flows $\phi_G(q)$ is known to be a polynomial in $q$. We extend the definition of nowhere-zero $\ZZ_q$-flows to simplicial complexes $\Delta$ of dimension greater than one, and prove the…

Combinatorics · Mathematics 2013-10-07 Matthias Beck , Yvonne Kemper

We present a series of analytically solvable axisymmetric flows on the torus geometry. For the single-component flows, we describe the propagation of sound waves for perfect fluids, as well as the viscous damping of shear and longitudinal…

Fluid Dynamics · Physics 2020-09-02 Sergiu Busuioc , Halim Kusumaatmaja , Victor E. Ambruş

We investigate flows on graphs whose links have random capacities. For binary trees we derive the probability distribution for the maximal flow from the root to a leaf, and show that for infinite trees it vanishes beyond a certain threshold…

Statistical Mechanics · Physics 2007-05-23 T. Antal , P. L. Krapivsky

The entropy of a digraph is a fundamental measure which relates network coding, information theory, and fixed points of finite dynamical systems. In this paper, we focus on the entropy of undirected graphs. We prove that for any integer $k$…

Information Theory · Computer Science 2015-12-07 Maximilien Gadouleau

There are many hard conjectures in graph theory, like Tutte's 5-flow conjecture, and the 5-cycle double cover conjecture, which would be true in general if they would be true for cubic graphs. Since most of them are trivially true for…

Combinatorics · Mathematics 2017-02-24 M. A. Fiol , G. Mazzuoccolo , E. Steffen

It is well known that each nonnegative integral flow on a graph can be decomposed into a sum of nonnegative graphic circuit flows, which cannot be further decomposed into nonnegative integral sub-flows. This is equivalent to saying that the…

Combinatorics · Mathematics 2021-06-21 Beifang Chen , Jue Wang , Thomas Zaslavsky

We show a fast algorithm for determining the set of edges in a planar undirected unweighted graph, whose deletion reduces the maximum flow between two fixed vertices. This is a special case of the max flow vitality problem, that has been…

Data Structures and Algorithms · Computer Science 2021-09-14 Giorgio Ausiello , Paolo G. Franciosa , Isabella Lari , Andrea Ribichini

We study the following conjecture of Matt DeVos: If there is a graph homomorphism from Cayley graph Cay(M, B) to another Cayley graph Cay(M', B') then every graph with an (M, B)-flow has an (M', B')-flow. This conjecture was originally…

Combinatorics · Mathematics 2019-01-11 Radek Hušek , Robert Šámal

The boundary conditions prescribing the constant traction or the so-called do-nothing conditions are frequently taken on artificial boundaries in the numerical simulations of steady flow of incompressible fluids, despite the fact that they…

Fluid Dynamics · Physics 2020-02-25 M. Lanzendörfer , J. Hron

Understanding how the cycles of a graph or digraph behave in general has always been an important point of graph theory. In this paper, we study the question of finding a set of $k$ vertex-disjoint cycles (resp. directed cycles) of distinct…

Combinatorics · Mathematics 2016-01-11 Julien Bensmail , Ararat Harutyunyan , Ngoc Khang Le , Binlong Li , Nicolas Lichiardopol

Using a certain well-posed ODE problem introduced by Shilnikov in the sixties, G. Minervini proved in his PhD thesis [17], among other things, the Harvey-Lawson Diagonal Theorem but without the restrictive tameness condition for Morse…

Differential Geometry · Mathematics 2020-04-03 Daniel Cibotaru , Wanderley Pereira

Consider the set $\chi^0_{\mathrm{nw}}$ of non-wandering continuous flows on a closed surface. Then such a flow can be approximated by regular non-wandering flows without heteroclinic connections nor locally dense orbits in…

Dynamical Systems · Mathematics 2017-07-19 Tomoo Yokoyama

An acyclic edge coloring of a graph $G$ is a proper edge coloring such that no bichromatic cycles are produced. The acyclic edge coloring conjecture by Fiam{\v{c}}ik (1978) and Alon, Sudakov and Zaks (2001) states that every simple graph…

Discrete Mathematics · Computer Science 2020-05-14 Qiaojun Shu , Guohui Lin , Eiji Miyano

We prove that every 2k-edge-connected graph with countably many edge-ends admits a k-arc-connected orientation, extending the previous result by Assem, Koloschin and Pitz that also assumed the hypothesis of the graph being locally finite.…

Combinatorics · Mathematics 2025-10-09 Leandro Aurichi , Paulo Magalhães Júnior , Guilherme Eduardo Pinto

A graph drawn in a surface is a near-quadrangulation if the sum of the lengths of the faces different from 4-faces is bounded by a fixed constant. We leverage duality between colorings and flows to design an efficient algorithm for…

Combinatorics · Mathematics 2023-03-13 Caroline Bang , Zdeněk Dvořák , Emily Heath , Bernard Lidický

We derive pointwise curvature estimates for graphical mean curvature flows in higher codimensions. To the best of our knowledge, this is the first such estimates without assuming smallness of first derivatives of the defining map. An…

Differential Geometry · Mathematics 2014-12-03 Knut Smoczyk , Mao-Pei Tsui , Mu-Tao Wang

We study graphs where each edge adjacent to a vertex of small degree (7 and 9, respectively) belongs to many triangles (4 and 5, respectively) and show that these graphs contain a complete graph (K_6 and K_7, respectively) as a minor. The…

Combinatorics · Mathematics 2013-04-22 Boris Albar , Daniel Gonçalves

Let $\phi_c(G)$ be the circular flow number of a bridgeless graph $G$. In [Edge-colorings and circular flow numbers of regular graphs, J. Graph Theory 79 (2015) 1-7] it was proved that, for every $t \geq 1$, $G$ is a bridgeless…

Combinatorics · Mathematics 2023-04-18 Davide Mattiolo , Eckhard Steffen