Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: On a problem of S.L. Sobolev   In 1930 Sergey L. Sobolev [7,8] has proposed a construction of the solution
of the Cauchy problem for the hyperbolic equation of the second order with
variable coefficients in 3-d. Although Sobolev did not construct the
fundamental solution, his construction was modified later by Romanov [4,5] to
obtain the fundamental solution. However, these works impose a restrictive
assumption of the regularity of geodesic lines in a large domain. In addition,
it is unclear how to realize those methods numerically. In this paper a simple
construction of a function, which is associated in a clear way with the
fundamental solution of the acoustic equation with the variable speed in 3-d,
is proposed. Conditions on geodesic lines are not imposed. An important feature
of this construction is that it lends itself to effective computations.

35
The categories of this paper are: mtrl-th
12
The categories of this paper are: nucl-th
33
The categories of this paper are: plasm-ph
1
The categories of this paper are: cs
31
The categories of this paper are: ao-sci
11
The categories of this paper are: hep-lat
32
The categories of this paper are: atom-ph
3
The categories of this paper are: physics
10
The categories of this paper are: q-bio
26
The categories of this paper are: bayes-an
21
The categories of this paper are: adap-org
8
The categories of this paper are: hep-ex
20
The categories of this paper are: acc-phys
5
The categories of this paper are: gr-qc
37
The categories of this paper are: supr-con
0
The categories of this paper are: hep-ph