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We generalise structure tree theory, which is based on removing finitely many edges, to removing finitely many vertices. This gives a significant generalization of Tutte's tree decomposition of 2-connected graphs into 3-connected blocks.…

Group Theory · Mathematics 2015-01-05 M. J. Dunwoody , B. Krön

In this paper it is shown that for any network there is a uniquely determined network based on a structure tree that provides a convenient way of determining a minimal cut separating a pair $s, t$ where each of $s, t$ is either a vertex or…

Combinatorics · Mathematics 2015-01-05 M. J. Dunwoody

We give a descriptive construction of trees for multi-ended graphs, which yields yet another proof of Stallings' theorem on ends of groups. Even though our proof is, in principle, not very different from already existing proofs and it draws…

Group Theory · Mathematics 2018-06-22 Anush Tserunyan

A self-contained account of the theory of structure trees for edge cuts in networks is given. Applications include a generalisation of the Max-Flow Min-Cut Theorem to infinite networks and a short proof of a conjecture of Kropholler. This…

Combinatorics · Mathematics 2016-01-27 M. J. Dunwoody

We consider infinite connected quasi-transitive locally finite graphs and show that every such graph with more than one end is a tree amalgamation of two other such graphs. This can be seen as a graph-theoretical version of Stallings'…

Combinatorics · Mathematics 2019-06-19 Matthias Hamann , Florian Lehner , Babak Miraftab , Tim Rühmann

We study edge-decompositions of highly connected graphs into copies of a given tree. In particular we attack the following conjecture by Bar\'at and Thomassen: for each tree $T$, there exists a natural number $k_T$ such that if $G$ is a…

Combinatorics · Mathematics 2012-03-09 János Barát , Dániel Gerbner

Considering systems of separations in a graph that separate every pair of a given set of vertex sets that are themselves not separated by these separations, we determine conditions under which such a separation system contains a nested…

Combinatorics · Mathematics 2014-09-02 Johannes Carmesin , Reinhard Diestel , Fabian Hundertmark , Maya Stein

We show that all the tangles in a finite graph or matroid can be distinguished by a single tree-decomposition that is invariant under the automorphisms of the graph or matroid. This comes as a corollary of a similar decomposition theorem…

Combinatorics · Mathematics 2017-04-19 Reinhard Diestel , Fabian Hundertmark , Sahar Lemanczyk

We give a short, topological proof that all graphs admit tree-decompositions displaying their topological ends.

Combinatorics · Mathematics 2021-12-03 Max Pitz

We prove that the edge-end space of an infinite graph is metrizable if and only if it is first-countable. This strengthens a recent result by Aurichi, Magalhaes Jr.\ and Real (2024). Our central graph-theoretic tool is the use of tree-cut…

Combinatorics · Mathematics 2025-07-23 Max Pitz

There are different definitions of ends in non-locally-finite graphs which are all equivalent in the locally finite case. We prove the compactness of the end-topology that is based on the principle of removing finite sets of vertices and…

Combinatorics · Mathematics 2009-10-31 B. Krön

The aim of this chapter is to provide an adequate graph theoretic framework for the description of periodic bifurcations which have recently been discovered in descendant trees of finite p-groups. The graph theoretic concepts of rooted…

Group Theory · Mathematics 2017-01-30 Daniel C. Mayer

In this paper we discuss reconstruction problems for graphs. We develop some new ideas like isomorphic extension of isomorphic graphs, partitioning of vertex sets into sets of equivalent points, subdeck property, etc. and develop an…

General Mathematics · Mathematics 2011-10-21 Dhananjay P. Mehendale

While finite graphs have tree-decompositions that efficiently distinguish all their tangles, locally finite graphs with thick ends need not have such tree-decompositions. We show that every locally finite graph without thick ends admits…

Combinatorics · Mathematics 2024-03-25 Raphael W. Jacobs , Paul Knappe

The Harary reconstruction conjecture states that any graph with more than four edges can be uniquely reconstructed from its set of maximal edge-deleted subgraphs. In 1977, M\"uller verified the conjecture for graphs with $n$ vertices and $n…

Combinatorics · Mathematics 2024-11-06 Anthony E. Pizzimenti , Umarkhon Rakhimov

Understanding the structure of a graph along with the structure of its subgraphs is important for several problems in graph theory. Two examples are the Reconstruction Conjecture and isomorph-free generation. This paper raises the question…

Combinatorics · Mathematics 2009-09-18 Stephen G. Hartke , Hannah Kolb , Jared Nishikawa , Derrick Stolee

We present an easy structure theorem for graphs which do not admit an immersion of the complete graph. The theorem motivates the definition of a variation of tree decompositions based on edge cuts instead of vertex cuts which we call…

Combinatorics · Mathematics 2014-07-02 Paul Wollan

Plural (or multiple-conclusion) cuts are inferences made by applying a structural rule introduced by Gentzen for his sequent formulation of classical logic. As singular (single-conclusion) cuts yield trees, which underlie ordinary natural…

Logic · Mathematics 2013-02-15 K. Dosen , Z. Petric

One of the major results of [N. Robertson and P. D. Seymour. Graph minors. XIII. The disjoint paths problem. J. Combin. Theory Ser. B, 63(1):65--110, 1995], also known as the weak structure theorem, revealed the local structure of graphs…

Combinatorics · Mathematics 2011-03-01 Archontia C. Giannopoulou , Dimitrios M. Thilikos

Dinits-Karzanov-Lomonosov showed that it is possible to encode all minimal edge cuts of a graph by a tree-like structure called a cactus. We show here that minimal edge cuts separating ends of the graph rather than vertices can be `encoded'…

Combinatorics · Mathematics 2011-10-25 Anastasia Evangelidou , Panos Papasoglu
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