Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: The Hamiltonian structure of the dispersionless Toda hierarchy   The Hamiltonian structure of the two-dimensional dispersionless Toda
hierarchy is studied, this being a particular example of a system of
hydrodynamic type. The polynomial conservation laws for the system turn out,
after a change of variable, to be associated with the axially symmetric
solutions of the 3-dimensional Laplace equation and this enables a generating
function for the Hamiltonian densities to be derived in closed form.

20
The categories of this paper are: acc-phys
32
The categories of this paper are: atom-ph
14
The categories of this paper are: math-ph
11
The categories of this paper are: hep-lat
31
The categories of this paper are: ao-sci
19
The categories of this paper are: eess
22
The categories of this paper are: chao-dyn
37
The categories of this paper are: supr-con
12
The categories of this paper are: nucl-th
34
The categories of this paper are: chem-ph
2
The categories of this paper are: math
27
The categories of this paper are: comp-gas
26
The categories of this paper are: bayes-an
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