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arXiv · 1604.03849

Counting isospectral manifolds

Mikhail Belolipetsky·Benjamin Linowitz
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Abstract

Given a simple Lie group $H$ of real rank at least $2$ we show that the maximum cardinality of a set of isospectral non-isometric $H$-locally symmetric spaces of volume at most $x$ grows at least as fast as $x^{c\log x/ (\log\log x)^2}$ where $c = c(H)$ is a positive constant. In contrast with the real rank $1$ case, this bound comes surprisingly close to the total number of such spaces as estimated in a previous work of Belolipetsky and Lubotzky [BL]. Our proof uses Sunada's method, results of [BL], and some deep results from number theory. We also discuss an open number-theoretical problem which would imply an even faster growth estimate.

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Mikhail Belolipetsky, Benjamin Linowitz. 2016-04-13. Counting isospectral manifolds. https://arxiv.org/abs/1604.03849

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