Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: The harmonic product of $\delta (x_{1},..., x_{n})$ and $\delta (x_{1})$
  and two combinatorial identities   In the framework of nonstandard analysis, Bang-He Li and the author defined
the product of any two distributions on $R^n$ via their harmonic
representations. The product of $\delta (x_{1},..., x_{n})$ and $\delta
(x_{1})$ was calculated by Kuribayashi and the author in [LK]. In this paper,
the result of [LK] is improved to $$\delta (x_{1},..., x_{n})\circ \delta
(x_{1}) =\dfrac{1}{2\pi\rho} \delta (x_{1},..., x_{n}) {mod} {infinitesimals}$$
where $\rho$ is a positive infinitesimal. Moreover two combinatorial identities
are obtained as byproducts.

11
The categories of this paper are: hep-lat
23
The categories of this paper are: solv-int
5
The categories of this paper are: gr-qc
29
The categories of this paper are: funct-an
0
The categories of this paper are: hep-ph
7
The categories of this paper are: hep-th
4
The categories of this paper are: cond-mat
22
The categories of this paper are: chao-dyn
14
The categories of this paper are: math-ph
34
The categories of this paper are: chem-ph
37
The categories of this paper are: supr-con
15
The categories of this paper are: nucl-ex
26
The categories of this paper are: bayes-an
3
The categories of this paper are: physics
8
The categories of this paper are: hep-ex
31
The categories of this paper are: ao-sci