Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Effective Infection Opportunity Population (EIOP) Hypothesis in Applying
  SIR Infection Theory   The SIR infection theory initiated by Kermack-Mckendrick in 1927 discusses
the infection in an isolated population with uniform properties such as the
uniform population distribution. In the infection, there exist two aspects: (1)
The quantitative aspect and (2) the temporal aspect. Since the SIR theory is a
mean-field theory, it can't match both aspects simultaneously. If the
quantitative aspect is matched, the temporal aspect can't be matched, versa.
The infection starts from a cluster, and it spreads to different places
increasing the size of the infection. In general, even in the case of the
infection in a big city, the infection grows within a limited population.
Namiki found and named this kind of population as an effective population. He
proposes that if the hypothesis is adopted, the quantitative and temporal
aspects can be matched simultaneously.

33
The categories of this paper are: plasm-ph
34
The categories of this paper are: chem-ph
4
The categories of this paper are: cond-mat
0
The categories of this paper are: hep-ph
5
The categories of this paper are: gr-qc
22
The categories of this paper are: chao-dyn
27
The categories of this paper are: comp-gas
7
The categories of this paper are: hep-th
2
The categories of this paper are: math
18
The categories of this paper are: econ
35
The categories of this paper are: mtrl-th
23
The categories of this paper are: solv-int
14
The categories of this paper are: math-ph
12
The categories of this paper are: nucl-th
1
The categories of this paper are: cs
28
The categories of this paper are: alg-geom