Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: A very short proof of Forester's rigidity result   The deformation space of a simplicial G-tree T is the set of G-trees which
can be obtained from T by some collapse and expansion moves, or equivalently,
which have the same elliptic subgroups as T. We give a short proof of a
rigidity result by Forester which gives a sufficient condition for a
deformation space to contain an Aut(G)-invariant G-tree. This gives a
sufficient condition for a JSJ splitting to be invariant under automorphisms of
G. More precisely, the theorem claims that a deformation space contains at most
one strongly slide-free G-tree, where strongly slide-free means the following:
whenever two edges e_1, e_2 incident on a same vertex v are such that G_{e_1}
is a subset of G_{e_2}, then e_1 and e_2 are in the same orbit under G_v.

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The categories of this paper are: nucl-th
35
The categories of this paper are: mtrl-th
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The categories of this paper are: chem-ph
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The categories of this paper are: q-bio
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The categories of this paper are: ao-sci
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The categories of this paper are: adap-org
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The categories of this paper are: nucl-ex
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The categories of this paper are: physics
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The categories of this paper are: alg-geom
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The categories of this paper are: chao-dyn
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The categories of this paper are: quant-ph
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The categories of this paper are: cond-mat
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The categories of this paper are: astro-ph
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The categories of this paper are: hep-lat
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The categories of this paper are: eess
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The categories of this paper are: supr-con