Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Topological Crystals   Sunada's work on topological crystallography emphasizes the role of the
"maximal abelian cover" of a graph $X$. This is a covering space of $X$ for
which the group of deck transformations is the first homology group
$H_1(X,\mathbb{Z})$. An embedding of the maximal abelian cover in a vector
space can serve as the pattern for a crystal: atoms are located at the
vertices, while bonds lie on the edges. We prove that for any connected graph
$X$ without bridges, there is a canonical way to embed the maximal abelian
cover of $X$ into the vector space $H_1(X,\mathbb{R})$. We call this a
"topological crystal". Crystals of graphene and diamond are examples of this
construction. We prove that any symmetry of a graph lifts to a symmetry of its
topological crystal. We also compute the density of atoms in this topological
crystal. We give special attention to the topological crystals coming from
Platonic solids. The key technical tools are a way of decomposing the 1-chain
coming from a path in $X$ into manageable pieces, and the work of Bacher, de la
Harpe and Nagnibeda on integral cycles and integral cuts.

11
The categories of this paper are: hep-lat
36
The categories of this paper are: cmp-lg
10
The categories of this paper are: q-bio
23
The categories of this paper are: solv-int
32
The categories of this paper are: atom-ph
0
The categories of this paper are: hep-ph
1
The categories of this paper are: cs
21
The categories of this paper are: adap-org
18
The categories of this paper are: econ
33
The categories of this paper are: plasm-ph
28
The categories of this paper are: alg-geom
8
The categories of this paper are: hep-ex
24
The categories of this paper are: dg-ga
34
The categories of this paper are: chem-ph
29
The categories of this paper are: funct-an
31
The categories of this paper are: ao-sci