Download this article
 Download this article For screen
For printing
Recent Issues

Volume 24
Issue 7, 3571–4137
Issue 6, 2971–3570
Issue 5, 2389–2970
Issue 4, 1809–2387
Issue 3, 1225–1808
Issue 2, 595–1223
Issue 1, 1–594

Volume 23, 9 issues

Volume 22, 8 issues

Volume 21, 7 issues

Volume 20, 7 issues

Volume 19, 7 issues

Volume 18, 7 issues

Volume 17, 6 issues

Volume 16, 6 issues

Volume 15, 6 issues

Volume 14, 6 issues

Volume 13, 6 issues

Volume 12, 4 issues

Volume 11, 5 issues

Volume 10, 4 issues

Volume 9, 4 issues

Volume 8, 4 issues

Volume 7, 4 issues

Volume 6, 5 issues

Volume 5, 4 issues

Volume 4, 2 issues

Volume 3, 2 issues

Volume 2, 2 issues

Volume 1, 2 issues

The Journal
About the Journal
Editorial Board
Subscriptions
 
Submission Guidelines
Submission Page
Policies for Authors
Ethics Statement
 
ISSN 1472-2739 (online)
ISSN 1472-2747 (print)
Author Index
To Appear
 
Other MSP Journals
Homology of configuration spaces of hard squares in a rectangle

Hannah Alpert, Ulrich Bauer, Matthew Kahle, Robert MacPherson and Kelly Spendlove

Algebraic & Geometric Topology 23 (2023) 2593–2626
Abstract

We study ordered configuration spaces C(n;p,q) of n hard squares in a p × q rectangle, a generalization of the well-known “15 puzzle”. Our main interest is in the topology of these spaces. Our first result describes a cubical cell complex and proves that it is homotopy equivalent to the configuration space. We then focus on determining for which n, j, p, and q the homology group Hj[C(n;p,q)] is nontrivial. We prove three homology-vanishing theorems, based on discrete Morse theory on the cell complex. Then we describe several explicit families of nontrivial cycles, and a method for interpolating between parameters to fill in most of the picture for “large-scale” nontrivial homology.

Keywords
homology, configuration spaces, statistical mechanics
Mathematical Subject Classification
Primary: 55R80
Secondary: 57Q70, 82B26
References
Publication
Received: 20 November 2020
Revised: 4 October 2021
Accepted: 20 December 2021
Published: 7 September 2023
Authors
Hannah Alpert
Department of Mathematics and Statistics
Auburn University
Auburn, AL
United States
Ulrich Bauer
Department of Mathematics
Technical University of Munich
Munich
Germany
Matthew Kahle
Department of Mathematics
Ohio State University
Columbus, OH
United States
Robert MacPherson
School of Mathematics
Institute for Advanced Study
Princeton, NJ
United States
Kelly Spendlove
Mathematical Institute
University of Oxford
Oxford
United Kingdom

Open Access made possible by participating institutions via Subscribe to Open.