Abstract
An isoperimetric inequality for the eigenfunctions of the Laplacian is proved, using rearrangements of functions. This result, together with a technique introduced by Payne, Polya, and Weinberger (J. Math. Phys., 35 (1956), pp. 289–298), gives an upper bound (not isoperimetric) for the ratio of the first two eigenvalues of a membrane.

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