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Combinatorial characterisations of minimal rigidity are obtained for symmetric 2-dimensional bar-joint frameworks with either $\ell^1$ or $\ell^\infty$ distance constraints. The characterisations are expressed in terms of symmetric tree…

Combinatorics · Mathematics 2016-04-01 Derek Kitson , Bernd Schulze

A bar-joint framework $(G,p)$ is the combination of a finite simple graph $G=(V,E)$ and a placement $p:V\rightarrow \mathbb{R}^d$. The framework is rigid if the only edge-length preserving continuous motions of the vertices arise from…

Combinatorics · Mathematics 2023-12-20 Anthony Nixon , Bernd Schulze , Joseph Wall

A rigidity theory is developed for frameworks in a metric space with two types of distance constraints. Mixed sparsity graph characterisations are obtained for the infinitesimal and continuous rigidity of completely regular bar-joint…

Metric Geometry · Mathematics 2019-08-26 Anthony Nixon , Stephen Power

The minimal infinitesimal rigidity of bar-joint frameworks in the non-Euclidean spaces (R^2, ||.||_q) are characterised in terms of (2,2)-tight graphs. Specifically, a generically placed bar-joint framework (G,p) in the plane is minimally…

Metric Geometry · Mathematics 2017-05-17 Derek Kitson , Stephen Power

In structural rigidity, one studies frameworks of bars and joints in Euclidean space. Such a framework is an articulated structure consisting of rigid bars, joined together at joints around which the bars may rotate. In this paper, we will…

Combinatorics · Mathematics 2024-08-28 Joannes Vermant , Klara Stokes

A bar-joint framework $(G,p)$ in the Euclidean space $\mathbb{E}^d$ is globally rigid if it is the unique realisation, up to rigid congruences, of $G$ in $\mathbb{E}^d$ with the edge lengths of $(G,p)$. Building on key results of…

Combinatorics · Mathematics 2022-06-16 Sean Dewar , John Hewetson , Anthony Nixon

A bar-joint framework $(G,p)$ is the combination of a graph $G$ and a map $p$ assigning positions, in some space, to the vertices of $G$. The framework is rigid if every edge-length-preserving continuous motion of the vertices arises from…

Combinatorics · Mathematics 2021-12-21 Sean Dewar , John Hewetson , Anthony Nixon

The rigidity matrix is a fundamental tool for studying the infinitesimal rigidity properties of Euclidean bar-joint frameworks. In this paper we generalize this tool and introduce a rigidity matrix for bar-joint frameworks in arbitrary…

Metric Geometry · Mathematics 2014-06-05 Derek Kitson , Bernd Schulze

Recent work has shown that if an isostatic bar and joint framework possesses non-trivial symmetries, then it must satisfy some very simply stated restrictions on the number of joints and bars that are `fixed' by various symmetry operations…

Metric Geometry · Mathematics 2009-07-14 Bernd Schulze

A bar-joint framework $(G,p)$ is the combination of a finite simple graph $G=(V,E)$ and a placement $p:V\rightarrow \mathbb{R}^d$. The framework is rigid if the only edge-length preserving continuous deformations of the vertices arise from…

Combinatorics · Mathematics 2023-12-18 Anthony Nixon , Bernd Schulze , Joseph Wall

A (bar-and-joint) framework is a set of points in a normed space with a set of fixed distance constraints between them. Determining whether a framework is locally rigid - i.e. whether every other suitably close framework with the same…

Metric Geometry · Mathematics 2024-01-18 Sean Dewar

As an extension of a classical tree-partition problem, we consider decompositions of graphs into edge-disjoint (rooted-)trees with an additional matroid constraint. Specifically, suppose we are given a graph $G=(V,E)$, a multiset…

Combinatorics · Mathematics 2011-09-06 Naoki Katoh , Shin-ichi Tanigawa

A realisation of a graph in the plane as a bar-joint framework is rigid if there are finitely many other realisations, up to isometries, with the same edge lengths. Each of these finitely-many realisations can be seen as a solution to a…

Combinatorics · Mathematics 2025-02-17 Oliver Clarke , Sean Dewar , Daniel Green Tripp , James Maxwell , Anthony Nixon , Yue Ren , Ben Smith

Some aspects of a mathematical theory of rigidity and flexibility are developed for general infinite frameworks and two main results are obtained. In the first sufficient conditions, of a uniform local nature, are obtained for the existence…

Functional Analysis · Mathematics 2008-11-19 J. C. Owen , S. C. Power

We consider the rigidity and global rigidity of bar-joint frameworks in Euclidean $d$-space under additional dilation constraints in specified coordinate directions. In this setting we obtain a complete characterisation of generic rigidity.…

Combinatorics · Mathematics 2024-02-23 Sean Dewar , Anthony Nixon , Andrew Sainsbury

A rigidity theory is developed for bar-joint frameworks in linear matrix spaces endowed with a unitarily invariant norm. Analogues of Maxwell's counting criteria are obtained and minimally rigid matrix frameworks are shown to belong to the…

Metric Geometry · Mathematics 2017-09-27 Derek Kitson , Rupert H. Levene

A longstanding problem in rigidity theory is to characterize the graphs which are minimally generically rigid in 3-space. The results of Cauchy, Dehn, and Alexandrov give one important class: the triangulated convex spheres, but there is an…

Metric Geometry · Mathematics 2010-07-07 Wendy Finbow-Singh , Walter Whiteley

We develop a rigidity theory for bar-joint frameworks in Euclidean $d$-space in which specified classes of edges are allowed to change length in a coordinated fashion that requires differences of lengths to be preserved within each class.…

Metric Geometry · Mathematics 2022-06-14 Bernd Schulze , Hattie Serocold , Louis Theran

We develop a combinatorial rigidity theory for symmetric bar-joint frameworks in a general finite dimensional normed space. In the case of rotational symmetry, matroidal Maxwell-type sparsity counts are identified for a large class of…

Metric Geometry · Mathematics 2020-04-17 Derek Kitson , Anthony Nixon , Bernd Schulze

We consider the global rigidity problem for bar-joint frameworks where each vertex is constrained to lie on a particular line in $\mathbb R^d$. In our setting we allow multiple vertices to be constrained to the same line. Under a mild…

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