We show that the ratio of the number of near perfect matchings to the number of perfect matchings in d-regular strong expander (non-bipartite) graphs, with 2n vertices, is a polynomial in n, thus the Jerrum and Sinclair Markov chain [Jerrum and Sinclair, 1989] mixes in polynomial time and generates an (almost) uniformly random perfect matching. Furthermore, we prove that such graphs have at least Ω(d)ⁿ many perfect matchings, thus proving the Lovasz-Plummer conjecture [L. Lovász and M.D. Plummer, 1986] for this family of graphs.
@InProceedings{ebrahimnejad_et_al:LIPIcs.ITCS.2022.61, author = {Ebrahimnejad, Farzam and Nagda, Ansh and Gharan, Shayan Oveis}, title = {{Counting and Sampling Perfect Matchings in Regular Expanding Non-Bipartite Graphs}}, booktitle = {13th Innovations in Theoretical Computer Science Conference (ITCS 2022)}, pages = {61:1--61:12}, series = {Leibniz International Proceedings in Informatics (LIPIcs)}, ISBN = {978-3-95977-217-4}, ISSN = {1868-8969}, year = {2022}, volume = {215}, editor = {Braverman, Mark}, publisher = {Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik}, address = {Dagstuhl, Germany}, URL = {https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.ITCS.2022.61}, URN = {urn:nbn:de:0030-drops-156579}, doi = {10.4230/LIPIcs.ITCS.2022.61}, annote = {Keywords: perfect matchings, approximate sampling, approximate counting, expanders} }
Feedback for Dagstuhl Publishing