Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: A direct proof of F. Riesz representation Theorem   A direct proof of the Riesz representation theorem is provided. This theorem
characterizes the linear functionals acting on the vector space $C(K)$ of
continuous functions defined on a compact subset $K$ of the real numbers
$\mathbb{R}$. This proof avoids complicated arguments commonly used in
generalizations of Riesz original theorem.

17
The categories of this paper are: q-fin
35
The categories of this paper are: mtrl-th
18
The categories of this paper are: econ
1
The categories of this paper are: cs
16
The categories of this paper are: stat
20
The categories of this paper are: acc-phys
8
The categories of this paper are: hep-ex
12
The categories of this paper are: nucl-th
3
The categories of this paper are: physics
29
The categories of this paper are: funct-an
34
The categories of this paper are: chem-ph
30
The categories of this paper are: q-alg
6
The categories of this paper are: astro-ph
37
The categories of this paper are: supr-con
15
The categories of this paper are: nucl-ex
7
The categories of this paper are: hep-th