Instruct: Identify the main and secondary category of Arxiv papers based on the titles
Query: A quantum walk with both a continuous-time and a continuous-spacetime
  limit
23
The categories of this paper are: solv-int
19
The categories of this paper are: eess
4
The categories of this paper are: cond-mat
5
The categories of this paper are: gr-qc
25
The categories of this paper are: patt-sol
9
The categories of this paper are: nlin
35
The categories of this paper are: mtrl-th
18
The categories of this paper are: econ
31
The categories of this paper are: ao-sci
22
The categories of this paper are: chao-dyn
30
The categories of this paper are: q-alg
8
The categories of this paper are: hep-ex
10
The categories of this paper are: q-bio
34
The categories of this paper are: chem-ph
2
The categories of this paper are: math
21
The categories of this paper are: adap-org