Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Sigma 1 of PL-homeomorphism groups   I survey the known results about the invariant Sigma 1 of groups of
PL-homeomorphisms of a compact interval and supplement them with new results
about Sigma 1 of PL-homeomorphism groups of a half line or a line. The proofs
are based on the Cayley-graph definition of the invariant.

27
The categories of this paper are: comp-gas
26
The categories of this paper are: bayes-an
15
The categories of this paper are: nucl-ex
8
The categories of this paper are: hep-ex
4
The categories of this paper are: cond-mat
34
The categories of this paper are: chem-ph
33
The categories of this paper are: plasm-ph
24
The categories of this paper are: dg-ga
7
The categories of this paper are: hep-th
36
The categories of this paper are: cmp-lg
0
The categories of this paper are: hep-ph
3
The categories of this paper are: physics
6
The categories of this paper are: astro-ph
28
The categories of this paper are: alg-geom
5
The categories of this paper are: gr-qc
9
The categories of this paper are: nlin