Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Generalized Q-functions and Dirichlet-to-Neumann maps for elliptic
  differential operators   The classical concept of $Q$-functions associated to symmetric and
selfadjoint operators due to M.G. Krein and H. Langer is extended in such a way
that the Dirichlet-to-Neumann map in the theory of elliptic differential
equations can be interpreted as a generalized $Q$-function. For couplings of
uniformly elliptic second order differential expression on bounded and
unbounded domains explicit Krein type formulas for the difference of the
resolvents and trace formulas in an $H^2$-framework are obtained.

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The categories of this paper are: patt-sol
37
The categories of this paper are: supr-con
27
The categories of this paper are: comp-gas
22
The categories of this paper are: chao-dyn
7
The categories of this paper are: hep-th
11
The categories of this paper are: hep-lat
36
The categories of this paper are: cmp-lg
31
The categories of this paper are: ao-sci
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The categories of this paper are: adap-org
5
The categories of this paper are: gr-qc
0
The categories of this paper are: hep-ph
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The categories of this paper are: nucl-th
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The categories of this paper are: chem-ph
30
The categories of this paper are: q-alg
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The categories of this paper are: q-fin
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The categories of this paper are: dg-ga