Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Multi-orbital frames through model spaces   We characterize the normal operators $A$ on $\ell^2$ and the elements $a^i
\in \ell^2$, with $1\le i\le m$, such that the sequence $$\{ A^n a^1 , \ldots ,
A^n a^m \}_{n\ge 0}$$ is a frame. The characterization makes strong use of the
pseudo-hyperbolic metric of $\mathbb{D}$ and is given in terms of the backward
shift invariant subspaces of $H^2(\mathbb{D})$ associated to finite products of
interpolating Blaschke products.

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The categories of this paper are: nucl-th
37
The categories of this paper are: supr-con
30
The categories of this paper are: q-alg
14
The categories of this paper are: math-ph
22
The categories of this paper are: chao-dyn
31
The categories of this paper are: ao-sci
36
The categories of this paper are: cmp-lg
5
The categories of this paper are: gr-qc
3
The categories of this paper are: physics
13
The categories of this paper are: quant-ph
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The categories of this paper are: hep-th
23
The categories of this paper are: solv-int
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The categories of this paper are: comp-gas
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The categories of this paper are: funct-an
0
The categories of this paper are: hep-ph
10
The categories of this paper are: q-bio