New York Journal of Mathematics
Volume 14 (2008) 193-204

  

Peter G. Doyle and Juan Pablo Rossetti

Isospectral hyperbolic surfaces have matching geodesics


Published: June 5, 2008
Keywords: Isospectrality, closed geodesic, holonomy, almost conjugate, hyperbolic surface, Selberg trace formula, flat orbifold, prime geodesic theorem
Subject: Primary: 58J53; Secondary: 11F72, 20F67, 53C22

Abstract
We show that if two closed hyperbolic surfaces (not necessarily orientable or even connected) have the same Laplace spectrum, then for every length they have the same number of orientation-preserving geodesics and the same number of orientation-reversing geodesics. Restricted to orientable surfaces, this result reduces to Huber's theorem of 1959. Appropriately generalized, it extends to hyperbolic 2-orbifolds (possibly disconnected). We give examples showing that it fails for disconnected flat 2-orbifolds.

Acknowledgements

Partially supported by DFG Sonderforschungsbereich 647, Humboldt University, Berlin.


Author information

Peter G. Doyle:
Dartmouth College
doyle@math.dartmouth.edu

Juan Pablo Rossetti:
FaMAF-CIEM, Univ. Nac. Córdoba
rossetti@mate.uncor.edu