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New York Journal of Mathematics
Volume 32 (2026), 1147-1170

  

Abhijit Champanerkar and Ilya Kofman

Geometric bounds for spanning tree entropy of planar lattice graphs

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Published: June 27, 2026.
Keywords: spanning tree entropy, hyperbolic volume, alternating link, Mahler measure, orthogonally dual graphs.
Subject [2020]: 57K32, 05C10, 57K10, 11R06.

Abstract
We prove infinitely many cases of conjectured sharp upper and lower bounds for the spanning tree entropy of any planar lattice graph. These bounds come from volumes of associated hyperbolic alternating links, right-angled hyperbolic polyhedra and hyperbolic regular ideal bipyramids. For many planar lattice graphs, we show these bounds are easy to compute and provide excellent numerical estimates for the spanning tree entropy.

Acknowledgements

The research of both authors is partially supported by grants from the Simons Foundation and PSC-CUNY.


Author information

Abhijit Champanerkar
Department of Mathematics
College of Staten Island & The Graduate Center
City University of New York
New York, NY 10016, USA

achampanerkar@gmail.com

Ilya Kofman
Department of Mathematics
College of Staten Island & The Graduate Center
City University of New York
New York, NY 10016, USA

Ilya.Kofman@csi.cuny.edu