Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Norm estimates of almost Mathieu operators   We estimate the norm of the almost Mathieu operator $H_{\theta,\lambda}
=U+U^*+(\lambda /2)(V+V^*)$ in the rotation $C^*$-algebra $A_\theta =C^*(U,V
unitaries;UV=e^{2\pi i\theta} VU)$. In this process, we significantly improve
the inequality $\| H_\theta \| \leq 2\sqrt{2}$, $\theta \in [0.25,0.5]$,
conjectured by Beguin, Valette and Zuk.

32
The categories of this paper are: atom-ph
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The categories of this paper are: comp-gas
17
The categories of this paper are: q-fin
23
The categories of this paper are: solv-int
15
The categories of this paper are: nucl-ex
9
The categories of this paper are: nlin
1
The categories of this paper are: cs
11
The categories of this paper are: hep-lat
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The categories of this paper are: ao-sci
4
The categories of this paper are: cond-mat
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The categories of this paper are: econ
20
The categories of this paper are: acc-phys
8
The categories of this paper are: hep-ex
3
The categories of this paper are: physics
7
The categories of this paper are: hep-th
33
The categories of this paper are: plasm-ph