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We prove a general width duality theorem for combinatorial structures with well-defined notions of cohesion and separation. These might be graphs and matroids, but can be much more general or quite different. The theorem asserts a duality…

Combinatorics · Mathematics 2021-01-19 Reinhard Diestel , Sang-il Oum

We prove a general duality theorem for tangle-like dense objects in combinatorial structures such as graphs and matroids. This paper continues, and assumes familiarity with, the theory developed in [6]

Combinatorics · Mathematics 2014-06-17 Reinhard Diestel , Sang-il Oum

We prove a duality theorem applicable to a a wide range of specialisations, as well as to some generalisations, of tangles in graphs. It generalises the classical tangle duality theorem of Robertson and Seymour, which says that every graph…

Combinatorics · Mathematics 2017-07-07 Reinhard Diestel , Philipp Eberenz , Joshua Erde

We demonstrate the versatility of the tangle-tree duality theorem for abstract separation systems by using it to prove tree-of-tangles theorems. This approach allows us to strengthen some of the existing tree-of-tangles theorems by bounding…

Combinatorics · Mathematics 2025-05-20 Christian Elbracht , Jay Lilian Kneip , Maximilian Teegen

Tangle-tree theorems are an important tool in structural graph theory, and abstract separation systems are a very general setting in which tangle-tree theorems can still be formulated and proven. For infinite abstract separation systems, so…

Combinatorics · Mathematics 2023-09-14 Ann-Kathrin Elm , Hendrik Heine

Tangle structure trees, introduced in [3], offer a unified data structure that displays all the tangles of a graph or data set together with certificates for the non-existence of any other tangles, either locally or overall. In this paper…

Combinatorics · Mathematics 2026-03-19 Hanno von Bergen , Reinhard Diestel

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

Robertson and Seymour proved two fundamental theorems about tangles in graphs: the tree-of-tangles theorem, which says that every graph has a tree-decomposition such that distinguishable tangles live in different nodes of the tree, and the…

Combinatorics · Mathematics 2025-01-08 Sandra Albrechtsen

We introduce a comprehensive data structure, tangle structure trees, which simultaneously displays all the $\mathcal{F}$-tangles of an abstract separation system for very general obstruction sets $\mathcal{F}$. It simultaneously also…

Combinatorics · Mathematics 2026-03-23 Hanno von Bergen , Reinhard Diestel

Treewidth is a graph parameter that plays a fundamental role in several structural and algorithmic results. We study the problem of decomposing a given graph $G$ into node-disjoint subgraphs, where each subgraph has sufficiently large…

Data Structures and Algorithms · Computer Science 2013-04-08 Chandra Chekuri , Julia Chuzhoy

In this paper we extend the theory of bidimensionality to two families of graphs that do not exclude fixed minors: map graphs and power graphs. In both cases we prove a polynomial relation between the treewidth of a graph in the family and…

Discrete Mathematics · Computer Science 2007-05-23 Erik D. Demaine , MohammadTaghi Hajiaghayi

We show how an image can, in principle, be described by the tangles of the graph of its pixels. The tangle-tree theorem provides a nested set of separations that efficiently distinguish all the distinguishable tangles in a graph. This…

Combinatorics · Mathematics 2017-11-09 Reinhard Diestel , Geoff Whittle

We extend to infinite graphs the matroidal characterization of finite graph duality, that two graphs are dual iff they have complementary spanning trees in some common edge set. The naive infinite analogue of this fails. The key in an…

Combinatorics · Mathematics 2011-06-08 Reinhard Diestel , Julian Pott

The twin-width of a graph measures its distance to co-graphs and generalizes classical width concepts such as tree-width or rank-width. Since its introduction in 2020 (Bonnet et. al. 2020), a mass of new results has appeared relating twin…

Combinatorics · Mathematics 2024-11-21 Irene Heinrich , Simon Raßmann

We extend Robertson and Seymour's tangle-tree duality theorem to infinite graphs.

Combinatorics · Mathematics 2026-03-13 Sandra Albrechtsen

Treewidth is a graph parameter of fundamental importance to algorithmic and structural graph theory. This paper surveys several graph parameters tied to treewidth, including separation number, tangle number, well-linked number and Cartesian…

Combinatorics · Mathematics 2016-01-29 Daniel J. Harvey , David R. Wood

Dynamic graph theory is a novel, growing area that deals with graphs that change over time and is of great utility in modelling modern wireless, mobile and dynamic environments. As a graph evolves, possibly arbitrarily, it is challenging to…

Computational Complexity · Computer Science 2012-05-28 Bernard Mans , Luke Mathieson

We prove canonical and non-canonical tree-of-tangles theorems for abstract separation systems that are merely structurally submodular. Our results imply all known tree-of-tangles theorems for graphs, matroids and abstract separation systems…

Combinatorics · Mathematics 2025-05-16 Christian Elbracht , Jay Lilian Kneip , Maximilian Teegen

We present infinite analogues of our splinter lemma from [Trees of tangles in abstract separation systems, arXiv:1909.09030]. From these we derive several tree-of-tangles-type theorems for infinite graphs and infinite abstract separation…

Combinatorics · Mathematics 2025-05-16 Christian Elbracht , Jay Lilian Kneip , Maximilian Teegen

Tree-cut width is a graph parameter introduced by Wollan that is an analogue of treewidth for the immersion order on graphs in the following sense: the tree-cut width of a graph is functionally equivalent to the largest size of a wall that…

Combinatorics · Mathematics 2022-08-12 Łukasz Bożyk , Oscar Defrain , Karolina Okrasa , Michał Pilipczuk
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