Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Lattices in R^2 and finite subsets of a circle   An elementary geometric construction is used to relate the space of lattices
in a plane to the space exp_3(S^1) of the subsets of a circle of cardinality at
most 3. As a consequence we obtain new proofs of a theorem of Bott which says
that exp_3(S^1) is homeomorphic to a 3-sphere and a theorem of Shchepin which
says that points of exp_3(S^1) that correspond to one-point subsets form a
trefoil knot in this 3-sphere.

17
The categories of this paper are: q-fin
27
The categories of this paper are: comp-gas
19
The categories of this paper are: eess
22
The categories of this paper are: chao-dyn
35
The categories of this paper are: mtrl-th
20
The categories of this paper are: acc-phys
29
The categories of this paper are: funct-an
16
The categories of this paper are: stat
18
The categories of this paper are: econ
8
The categories of this paper are: hep-ex
23
The categories of this paper are: solv-int
21
The categories of this paper are: adap-org
0
The categories of this paper are: hep-ph
32
The categories of this paper are: atom-ph
33
The categories of this paper are: plasm-ph
11
The categories of this paper are: hep-lat