Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Necessary Conditions for K/2 Degrees of Freedom   Stotz et al., 2016, reported a sufficient (injectivity) condition for each
user in a K-user single-antenna constant interference channel to achieve 1/2
degree of freedom. The present paper proves that this condition is necessary as
well and hence provides an equivalence characterization of interference channel
matrices allowing full degrees of freedom.

18
The categories of this paper are: econ
7
The categories of this paper are: hep-th
17
The categories of this paper are: q-fin
0
The categories of this paper are: hep-ph
35
The categories of this paper are: mtrl-th
25
The categories of this paper are: patt-sol
11
The categories of this paper are: hep-lat
4
The categories of this paper are: cond-mat
31
The categories of this paper are: ao-sci
27
The categories of this paper are: comp-gas
28
The categories of this paper are: alg-geom
5
The categories of this paper are: gr-qc
29
The categories of this paper are: funct-an
22
The categories of this paper are: chao-dyn
24
The categories of this paper are: dg-ga
32
The categories of this paper are: atom-ph