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Proceedings of the American Mathematical Society

Published by the American Mathematical Society since 1950, Proceedings of the American Mathematical Society is devoted to shorter research articles in all areas of pure and applied mathematics.

ISSN 1088-6826 (online) ISSN 0002-9939 (print)

The 2020 MCQ for Proceedings of the American Mathematical Society is 0.85.

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The first eigenvalue of a scalene triangle
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by Robert Brooks and Peter Waksman PDF
Proc. Amer. Math. Soc. 100 (1987), 175-182 Request permission

Abstract:

In this paper, we prove the lower bound \[ {\lambda _1}(T) \geq \frac {{(L + \sqrt {4\pi A{)^2}} }}{{16{A^2}}}\] for a triangle $T$ with area $A$ and perimeter $L$, where ${\lambda _1}$ is the first eigenvalue for the Laplace operator with Dirichlet boundary conditions. We also present analogous estimates for an arbitrary convex polygon.
References
  • Robert Brooks, The fundamental group and the spectrum of the Laplacian, Comment. Math. Helv. 56 (1981), no. 4, 581–598. MR 656213, DOI 10.1007/BF02566228
  • Jeff Cheeger, A lower bound for the smallest eigenvalue of the Laplacian, Problems in analysis (Papers dedicated to Salomon Bochner, 1969) Princeton Univ. Press, Princeton, N. J., 1970, pp. 195–199. MR 0402831
  • Herbert Federer, Geometric measure theory, Die Grundlehren der mathematischen Wissenschaften, Band 153, Springer-Verlag New York, Inc., New York, 1969. MR 0257325
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Additional Information
  • © Copyright 1987 American Mathematical Society
  • Journal: Proc. Amer. Math. Soc. 100 (1987), 175-182
  • MSC: Primary 58G25; Secondary 35P15
  • DOI: https://doi.org/10.1090/S0002-9939-1987-0883424-1
  • MathSciNet review: 883424