Instruct: Identify the main and secondary category of Arxiv papers based on the titles
Query: A Unified Filter for Simultaneous Input and State Estimation of Linear
  Discrete-time Stochastic Systems
22
The categories of this paper are: chao-dyn
5
The categories of this paper are: gr-qc
16
The categories of this paper are: stat
14
The categories of this paper are: math-ph
31
The categories of this paper are: ao-sci
21
The categories of this paper are: adap-org
6
The categories of this paper are: astro-ph
4
The categories of this paper are: cond-mat
7
The categories of this paper are: hep-th
30
The categories of this paper are: q-alg
24
The categories of this paper are: dg-ga
26
The categories of this paper are: bayes-an
18
The categories of this paper are: econ
33
The categories of this paper are: plasm-ph
8
The categories of this paper are: hep-ex
13
The categories of this paper are: quant-ph