Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Commensurators and Quasi-Normal Subgroups   We say A is a quasi-normal subgroup of the group G if the commensurator of A
in G is all of G. We develop geometric versions of commensurators in finitely
generated groups. In particular, g is an element of the commensurator of A in G
iff the Hausdorff distance between A and gA is finite.
  We show that a quasi-normal subgroup of a group is the kernel of a certain
map, and a subgroup of a finitely generated group is quasi-normal iff the
natural coset graph is locally finite. This last equivalence is particularly
useful for deriving asymptotic results for finitely generated groups. Our
primary goal in this paper is to develop the basic theory of quasi-normal
subgroups, comparing analogous results for normal subgroups and isolating
differences between quasi-normal and normal subgroups.

20
The categories of this paper are: acc-phys
3
The categories of this paper are: physics
17
The categories of this paper are: q-fin
11
The categories of this paper are: hep-lat
12
The categories of this paper are: nucl-th
6
The categories of this paper are: astro-ph
19
The categories of this paper are: eess
35
The categories of this paper are: mtrl-th
8
The categories of this paper are: hep-ex
22
The categories of this paper are: chao-dyn
4
The categories of this paper are: cond-mat
0
The categories of this paper are: hep-ph
28
The categories of this paper are: alg-geom
10
The categories of this paper are: q-bio
25
The categories of this paper are: patt-sol
15
The categories of this paper are: nucl-ex