Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Isospectral flat 3-manifolds   There is a well-known problem about isospectrality of Riemannian manifolds:
whether isospectral manifolds are isometric. In this work we give an answer to
this problem for 3-dimensional compact flat manifolds.

16
The categories of this paper are: stat
11
The categories of this paper are: hep-lat
10
The categories of this paper are: q-bio
3
The categories of this paper are: physics
23
The categories of this paper are: solv-int
17
The categories of this paper are: q-fin
27
The categories of this paper are: comp-gas
37
The categories of this paper are: supr-con
31
The categories of this paper are: ao-sci
9
The categories of this paper are: nlin
35
The categories of this paper are: mtrl-th
20
The categories of this paper are: acc-phys
0
The categories of this paper are: hep-ph
7
The categories of this paper are: hep-th
26
The categories of this paper are: bayes-an
12
The categories of this paper are: nucl-th