English

A counterexample to the Hirsch conjecture

Combinatorics 2013-04-30 v3 Discrete Mathematics Optimization and Control

Abstract

The Hirsch Conjecture (1957) stated that the graph of a dd-dimensional polytope with nn facets cannot have (combinatorial) diameter greater than ndn-d. That is, that any two vertices of the polytope can be connected by a path of at most ndn-d edges. This paper presents the first counterexample to the conjecture. Our polytope has dimension 43 and 86 facets. It is obtained from a 5-dimensional polytope with 48 facets which violates a certain generalization of the dd-step conjecture of Klee and Walkup.

Keywords

Cite

@article{arxiv.1006.2814,
  title  = {A counterexample to the Hirsch conjecture},
  author = {Francisco Santos},
  journal= {arXiv preprint arXiv:1006.2814},
  year   = {2013}
}

Comments

28 pages, 10 Figures: Changes from v2: Minor edits suggested by referees. This version has been accepted in the Annals of Mathematics

R2 v1 2026-06-21T15:36:06.746Z