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Laman graphs model planar frameworks that are rigid for a general choice of distances between the vertices. There are finitely many ways, up to isometries, to realize a Laman graph in the plane. Such realizations can be seen as solutions of…

Algebraic Geometry · Mathematics 2021-03-18 Jose Capco , Matteo Gallet , Georg Grasegger , Christoph Koutschan , Niels Lubbes , Josef Schicho

Laman graphs model planar frameworks which are rigid for a general choice of distances between the vertices. There are finitely many ways, up to isometries, to realize a Laman graph in the plane. In a recent paper we provide a recursion…

Combinatorics · Mathematics 2017-10-12 Jose Capco , Matteo Gallet , Georg Grasegger , Christoph Koutschan , Niels Lubbes , Josef Schicho

Computing the number of realizations of a minimally rigid graph is a notoriously difficult problem. Towards this goal, for graphs that are minimally rigid in the plane, we take advantage of a recently published algorithm, which is the…

Combinatorics · Mathematics 2018-04-12 Georg Grasegger , Christoph Koutschan , Elias Tsigaridas

Rigid graphs have only finitely many realizations. In the recent years significant progress was made in computing the number of such realizations. With this progress it was also possible for the first time to do computations on large sets…

Combinatorics · Mathematics 2025-02-10 Georg Grasegger

A theorem of Laman gives a combinatorial characterisation of the graphs that admit a realisation as a minimally rigid generic bar-joint framework in $\bR^2$. A more general theory is developed for frameworks in $\bR^3$ whose vertices are…

Combinatorics · Mathematics 2012-10-05 A. Nixon , J. C. Owen , S. C. Power

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

Graph rigidity theory studies the capability of a graph embedded in the Euclidean space to constrain its global geometric shape via local constraints among nodes and edges, and has been widely exploited in network localization and formation…

Optimization and Control · Mathematics 2025-06-05 Jinpeng Huang , Gangshan Jing

We introduce a recursive procedure for computing the number of realizations of a minimally rigid graph on the sphere up to rotations. We accomplish this by combining two ingredients. The first is a framework that allows us to think of such…

Combinatorics · Mathematics 2023-08-30 Matteo Gallet , Georg Grasegger , Niels Lubbes , Josef Schicho

A graph is called (generically) rigid in R^d if, for any choice of sufficiently generic edge lengths, it can be embedded in R^d in a finite number of distinct ways, modulo rigid transformations. Here, we deal with the problem of determining…

Computational Geometry · Computer Science 2014-10-24 Stylianos C. Despotakis , Ioannis Z. Emiris

A Laman graph $G$ is a minimally rigid graph in dimension two, and its realization number is its number of distinct embeddings with fixed generic edge lengths. While conjectured to grow exponentially in the number of vertices of $G$, the…

Combinatorics · Mathematics 2025-11-13 Amelia Bielby , Arushi Chauhan , Cassia Pearce , Yue Ren

Rigidity theory studies the properties of graphs that can have rigid embeddings in a euclidean space $\mathbb{R}^d$ or on a sphere and which in addition satisfy certain edge length constraints. One of the major open problems in this field…

Algebraic Geometry · Mathematics 2021-02-05 Evangelos Bartzos , Ioannis Z. Emiris , Jan Legerský , Elias Tsigaridas

A graph is said to be rigid if, given a generic realisation of the graph as a bar-and-joint framework in the plane, there exist only finitely many other realisations of the graph with the same edge lengths modulo rotations, reflections and…

Combinatorics · Mathematics 2025-10-07 Sean Dewar , Georg Grasegger , Josef Schicho , Ayush Kumar Tewari , Audie Warren

The number of embeddings of minimally rigid graphs in $\mathbb{R}^D$ is (by definition) finite, modulo rigid transformations, for every generic choice of edge lengths. Even though various approaches have been proposed to compute it, the gap…

Algebraic Geometry · Mathematics 2020-01-24 Evangelos Bartzos , Ioannis Emiris , Jan Legerský , Elias Tsigaridas

Laman graphs are fundamental to rigidity theory. A graph G with n vertices and m edges is a generic minimally rigid graph (Laman graph), if m=2n-3 and every induced subset of k vertices spans at most 2k-3 edges. We consider the verification…

Combinatorics · Mathematics 2008-01-17 Ovidiu Daescu , Anastasia Kurdia

It is shown that a simple graph which is embeddable in the real projective plane is minimally 3-rigid if and only if it is (3,6)-tight. Moreover the topologically uncontractible embedded graphs of this type are constructible from one of 8…

Combinatorics · Mathematics 2023-02-20 Eleftherios Kastis , Stephen Power

Rigid frameworks in some Euclidian space are embedded graphs having a unique local realization (up to Euclidian motions) for the given edge lengths, although globally they may have several. We study the number of distinct planar embeddings…

Metric Geometry · Mathematics 2007-05-23 Ciprian Borcea , Ileana Streinu

We present an algorithm that computes the number of realizations of a Laman graph on a sphere for a general choice of the angles between the vertices. The algorithm is based on the interpretation of such a realization as a point in the…

Combinatorics · Mathematics 2021-03-18 Matteo Gallet , Georg Grasegger , Josef Schicho

We explore the rigidity of generic frameworks in 3-dimensions whose underlying graph is close to being planar. Specifically we consider apex graphs, edge-apex graphs and their variants and prove independence results in the generic…

Combinatorics · Mathematics 2024-02-28 Sean Dewar , Georg Grasegger , Eleftherios Kastis , Anthony Nixon , Brigitte Servatius

A linkage is a finite graph with lengths assigned to each edge. A planar realization is a map to the plane which preserves edge lengths. It can be thought of as a mechanical device formed from stiff rods and rotating joints. We look at the…

Algebraic Geometry · Mathematics 2007-05-23 Henry C. King

Laman graphs naturally arise in structural mechanics and rigidity theory. Specifically, they characterize minimally rigid planar bar-and-joint systems which are frequently needed in robotics, as well as in molecular chemistry and polymer…

Combinatorics · Mathematics 2012-10-01 Stephen Kobourov , Torsten Ueckerdt , Kevin Verbeek
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