Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: The Solution of the Modified Helmholtz Equation in a Triangular Domain
  and an Application to Diffusion-Limited Coalescence   A new transform method for solving boundary value problems for linear and
integrable nonlinear PDEs recently introduced in the literature is used here to
obtain the solution of the modified Helmholtz equation
q_{xx}(x,y)+q_{yy}(x,y)-4b^2q(x,y)=0 in the triangular domain 0 < x < L-y < L,
with mixed boundary conditions. This solution is applied to the problem of
diffusion-limited coalescence, A + A <--> A, in the segment (-L/2,L/2), with
traps at the edges.

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The categories of this paper are: q-bio
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The categories of this paper are: solv-int
12
The categories of this paper are: nucl-th
34
The categories of this paper are: chem-ph
16
The categories of this paper are: stat
8
The categories of this paper are: hep-ex
7
The categories of this paper are: hep-th
18
The categories of this paper are: econ
36
The categories of this paper are: cmp-lg
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The categories of this paper are: acc-phys
30
The categories of this paper are: q-alg
0
The categories of this paper are: hep-ph
28
The categories of this paper are: alg-geom
33
The categories of this paper are: plasm-ph
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The categories of this paper are: math-ph
22
The categories of this paper are: chao-dyn