Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Auxetic properties and anisotropy of elastic material constants of 2D
  crystalline media   Anisotropies of Young's modulus E, the shear modulus G, and Poisson's ratio
of all 2D symmetry systems are studied. Simple necessary and sufficient
conditions on their elastic compliances are derived to identify if any of these
crystals are completely auxetic, non-auxetic and auxetic. Particular attention
is paid to 2D crystals of quadratic symmetry. All mechanically stable quadratic
crystals are characterized by three parameters belonging to a prism with the
stability triangle in the base. Regions in the stability triangle in which
quadratic materials are completely auxetic, non-auxetic, and auxetic are
established. Examples of all types of auxetic properties of crystals of oblique
and rectangular symmetry are presented.

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The categories of this paper are: plasm-ph
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The categories of this paper are: ao-sci
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The categories of this paper are: hep-th
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The categories of this paper are: cs
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The categories of this paper are: econ
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The categories of this paper are: nucl-ex
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The categories of this paper are: math-ph
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The categories of this paper are: alg-geom
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The categories of this paper are: hep-lat
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The categories of this paper are: stat
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The categories of this paper are: patt-sol
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The categories of this paper are: atom-ph
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The categories of this paper are: q-fin
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The categories of this paper are: nlin
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The categories of this paper are: astro-ph
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The categories of this paper are: q-bio