Relatively equivalent representations and isospectral Riemannian manifolds
The author establishes a generalization of a result of \textit{T. Sunada} [Ann. Math., II. Ser. 121, 169-186 (1985; Zbl 0585.58047)] about the construction of isospectral manifolds which are nonisometric. The condition given by the author is weaker than the one used by T. Sunada and is also formulated in terms of equivalence of representations. This condition, in some cases, is a condition necessary and sufficient under which two locally isometric manifolds are isospectral.
scientific article; zbMATH DE number 919898