Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Which subnormal Toeplitz operators are either normal or analytic?   We study subnormal Toeplitz operators on the vector-valued Hardy space of the
unit circle, along with an appropriate reformulation of P.R. Halmos's Problem
5: Which subnormal block Toeplitz operators are either normal or analytic? We
extend and prove Abrahamse's Theorem to the case of matrix-valued symbols; that
is, we show that every subnormal block Toeplitz operator with bounded type
symbol (i.e., a quotient of two analytic functions), whose co-analytic part has
a "coprime decomposition," is normal or analytic. We also prove that the
coprime decomposition condition is essential. Finally, we examine a well known
conjecture, of whether every submormal Toeplitz operator with finite rank
self-commutator is normal or analytic.

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The categories of this paper are: funct-an
21
The categories of this paper are: adap-org
8
The categories of this paper are: hep-ex
26
The categories of this paper are: bayes-an
10
The categories of this paper are: q-bio
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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: eess
14
The categories of this paper are: math-ph
27
The categories of this paper are: comp-gas
4
The categories of this paper are: cond-mat
6
The categories of this paper are: astro-ph
1
The categories of this paper are: cs
20
The categories of this paper are: acc-phys
17
The categories of this paper are: q-fin
0
The categories of this paper are: hep-ph