Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Real sets   After reviewing a universal characterization of the extended positive real
numbers published by Denis Higgs in 1978, we define a category which provides
an answer to the questions: \begin{itemize} \item what is a set with half an
element? \item what is a set with $\pi$ elements? \end{itemize} The category of
these extended positive real sets is equipped with a countable tensor product.
We develop somewhat the theory of categories with countable tensors; we call
the commutative such categories {\em series monoidal} and conclude by only
briefly mentioning the non-commutative possibility called {\em
$\omega$-monoidal}. We include some remarks on sets having cardinalities in
$[-\infty,\infty]$.

18
The categories of this paper are: econ
34
The categories of this paper are: chem-ph
22
The categories of this paper are: chao-dyn
21
The categories of this paper are: adap-org
36
The categories of this paper are: cmp-lg
37
The categories of this paper are: supr-con
28
The categories of this paper are: alg-geom
25
The categories of this paper are: patt-sol
13
The categories of this paper are: quant-ph
19
The categories of this paper are: eess
35
The categories of this paper are: mtrl-th
7
The categories of this paper are: hep-th
10
The categories of this paper are: q-bio
16
The categories of this paper are: stat
3
The categories of this paper are: physics
12
The categories of this paper are: nucl-th