Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Projections and idempotents with fixed diagonal and the homotopy problem
  for unit tight frames   We investigate the topological and metric structure of the set of idempotent
operators and projections which have prescribed diagonal entries with respect
to a fixed orthonormal basis of a Hilbert space. As an application, we settle
some cases of conjectures of Larson, Dykema, and Strawn on the connectedness of
the set of unit-norm tight frames.

26
The categories of this paper are: bayes-an
22
The categories of this paper are: chao-dyn
6
The categories of this paper are: astro-ph
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The categories of this paper are: dg-ga
19
The categories of this paper are: eess
7
The categories of this paper are: hep-th
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The categories of this paper are: alg-geom
8
The categories of this paper are: hep-ex
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The categories of this paper are: chem-ph
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The categories of this paper are: cmp-lg
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The categories of this paper are: mtrl-th
14
The categories of this paper are: math-ph
33
The categories of this paper are: plasm-ph
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The categories of this paper are: ao-sci
16
The categories of this paper are: stat
25
The categories of this paper are: patt-sol