Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Index of $\Gamma$-equivariant Toeplitz operators   Let $\Gamma$ be a discrete icc subgroup of PSL(2,R) of infinite covolume. and
let M denote the quotient of the unit disc by $\Gamma$. We prove that a
Toeplitz operator with $\Gamma$-invariant symbol f in C(M) is Brauer Fredholm
if its symbol is invertible on the boundary of M and its Brauer index is equal
to the winding number of f at the boundary. We construct the associated
extension of the algebra of functions continuous on the boundary of M by the
Brauer ideal in the C*-algebra generated by such operators.

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The categories of this paper are: acc-phys
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The categories of this paper are: atom-ph
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The categories of this paper are: bayes-an
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The categories of this paper are: nlin
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The categories of this paper are: supr-con
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The categories of this paper are: adap-org
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The categories of this paper are: chao-dyn
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The categories of this paper are: alg-geom
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The categories of this paper are: cond-mat
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The categories of this paper are: gr-qc
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The categories of this paper are: nucl-ex
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The categories of this paper are: chem-ph
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The categories of this paper are: q-fin
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The categories of this paper are: patt-sol
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The categories of this paper are: dg-ga
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The categories of this paper are: mtrl-th