Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: An elementary approach to the Daugavet equation   Let $T\dopu C(S)\to C(S)$ be a bounded linear operator. We present a
necessary and sufficient condition for the so-called Daugavet equation $$
\|\Id+T\| = 1+\|T\| $$ to hold, and we apply it to weakly compact operators and
to operators factoring through $c_{0}$. Thus we obtain very simple proofs of
results by Foias, Singer, Pelczynski, Holub and others.

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The categories of this paper are: alg-geom
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The categories of this paper are: mtrl-th
13
The categories of this paper are: quant-ph
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The categories of this paper are: comp-gas
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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: chao-dyn
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The categories of this paper are: eess
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The categories of this paper are: dg-ga
3
The categories of this paper are: physics
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The categories of this paper are: econ
10
The categories of this paper are: q-bio
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The categories of this paper are: cs
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The categories of this paper are: ao-sci
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The categories of this paper are: acc-phys
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The categories of this paper are: math-ph