Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Lyapunov Exponents and KS Entropy for the Lorentz Gas at Low Densities   The Lyapunov exponents and the KS entropy for a two dimensional Lorentz gas
at low densities are defined for general non-equilibrium states and calculated
with the use of a Lorentz-Boltzmann type equation. In equilibrium the density
dependence of these quantities predicted by Krylov is recovered and explicit
expressions are obtained. The relationship between the KS entropy, Lyapunov
exponents, and escape rate, conjectured by Gaspard and Nicolis for
non-equilibrium systems is confirmed and generalized.

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The categories of this paper are: hep-ex
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The categories of this paper are: physics
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The categories of this paper are: adap-org
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The categories of this paper are: dg-ga
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The categories of this paper are: funct-an
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The categories of this paper are: cond-mat
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The categories of this paper are: nucl-th
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The categories of this paper are: math
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The categories of this paper are: plasm-ph
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The categories of this paper are: bayes-an
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The categories of this paper are: ao-sci
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The categories of this paper are: econ
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The categories of this paper are: quant-ph
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The categories of this paper are: patt-sol
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The categories of this paper are: hep-ph
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The categories of this paper are: hep-th