Results 11 to 20 of about 95 (88)
Deforming cubulations of hyperbolic groups
Journal of Topology, Volume 14, Issue 3, Page 877-912, September 2021., 2021 Abstract We describe a procedure to deform cubulations of hyperbolic groups by ‘bending hyperplanes’. Our construction is inspired by related constructions like Thurston's Mickey Mouse example, walls in fibred hyperbolic 3‐manifolds and free‐by‐Z groups, and Hsu–Wise turns.
Elia Fioravanti, Mark Hagen
wiley +1 more source
A new obstruction for normal spanning trees
Bulletin of the London Mathematical Society, Volume 53, Issue 4, Page 1220-1227, August 2021., 2021 Abstract In a paper from 2001 (Journal of the LMS), Diestel and Leader offered a proof that a connected graph has a normal spanning tree if and only if it has no minor obtained canonically from either an (ℵ0,ℵ1)‐regular bipartite graph or an order‐theoretic Aronszajn tree. In particular, this refuted an earlier conjecture of Halin's that only the first
Max Pitz
wiley +1 more source
Robust flows with adaptive mitigation
EURO Journal on Computational Optimization, 2021 We consider an adjustable robust optimization problem arising in the area of supply chains: given sets of suppliers and demand nodes, we wish to find a flow that is robust with respect to failures of the suppliers.
Heiner Ackermann +2 more
doaj +1 more source
Sparse Kneser graphs are Hamiltonian
Journal of the London Mathematical Society, Volume 103, Issue 4, Page 1253-1275, June 2021., 2021 Abstract For integers k⩾1 and n⩾2k+1, the Kneser graph K(n,k) is the graph whose vertices are the k‐element subsets of {1,…,n} and whose edges connect pairs of subsets that are disjoint. The Kneser graphs of the form K(2k+1,k) are also known as the odd graphs.
Torsten Mütze +2 more
wiley +1 more source
(Un)distorted stabilisers in the handlebody group
Journal of Topology, Volume 14, Issue 2, Page 460-487, June 2021., 2021 Abstract We study geometric properties of stabilisers in the handlebody group. We find that stabilisers of meridians are undistorted, while stabilisers of primitive curves or annuli are exponentially distorted for large enough genus.
Sebastian Hensel
wiley +1 more source
Quasi‐isometric diversity of marked groups
Journal of Topology, Volume 14, Issue 2, Page 488-503, June 2021., 2021 Abstract We use basic tools of descriptive set theory to prove that a closed set S of marked groups has 2ℵ0 quasi‐isometry classes, provided that every non‐empty open subset of S contains at least two non‐quasi‐isometric groups. It follows that every perfect set of marked groups having a dense subset of finitely presented groups contains 2ℵ0 quasi ...
A. Minasyan, D. Osin, S. Witzel
wiley +1 more source
The extremal number of longer subdivisions
Bulletin of the London Mathematical Society, Volume 53, Issue 1, Page 108-118, February 2021., 2021 Abstract For a multigraph F, the k‐subdivision of F is the graph obtained by replacing the edges of F with pairwise internally vertex‐disjoint paths of length k+1. Conlon and Lee conjectured that if k is even, then the (k−1)‐subdivision of any multigraph has extremal number O(n1+1k), and moreover, that for any simple graph F there exists ε>0 such that ...
Oliver Janzer
wiley +1 more source
Stop location design in public transportation networks: covering and accessibility objectives [PDF]
, 2006 Location, Public transportation, Covering, Accessibility, 90B80, 90C10, 90C35, 90B20,
Poetranto, Dwi Retnani +9 more
core +1 more source
Improving the linear relaxation of maximum k-cut with semidefinite-based constraints
EURO Journal on Computational Optimization, 2019 We consider the maximum k-cut problem that involves partitioning the vertex set of a graph into k subsets such that the sum of the weights of the edges joining vertices in different subsets is maximized.
VilmarJefté Rodrigues de Sousa +2 more
doaj +1 more source
Injectivity results for coarse homology theories
Proceedings of the London Mathematical Society, Volume 121, Issue 6, Page 1619-1684, December 2020., 2020 Abstract We show injectivity results for assembly maps using equivariant coarse homology theories with transfers. Our method is based on the descent principle and applies to a large class of linear groups or, more generally, groups with finite decomposition complexity.
Ulrich Bunke +3 more
wiley +1 more source