Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Linear wave systems on $n$-D spatial domains   In this paper we study the linear wave equation on an $n$-dimensional spatial
domain. We show that there is a boundary triplet associated to the undamped
wave equation. This enables us to characterise all boundary conditions for
which the undamped wave equation possesses a unique solution non-increasing in
the energy. Furthermore, we add boundary inputs and outputs to the system, thus
turning it into an impedance conservative boundary control system.

29
The categories of this paper are: funct-an
13
The categories of this paper are: quant-ph
27
The categories of this paper are: comp-gas
25
The categories of this paper are: patt-sol
18
The categories of this paper are: econ
23
The categories of this paper are: solv-int
0
The categories of this paper are: hep-ph
37
The categories of this paper are: supr-con
4
The categories of this paper are: cond-mat
10
The categories of this paper are: q-bio
35
The categories of this paper are: mtrl-th
19
The categories of this paper are: eess
8
The categories of this paper are: hep-ex
21
The categories of this paper are: adap-org
11
The categories of this paper are: hep-lat
6
The categories of this paper are: astro-ph