Schillewaert, J.; Thas, K.
(Symmetry, Integrability and Geometry: Methods and Applications, 2011)
For Riemannian manifolds there are several examples which are isospectral but not isometric, see e.g. J. Milnor [Proc. Nat. Acad. Sci. USA 51 (1964), 542]; in the present paper, we investigate pairs of domains in R² which ...