Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Diagonalization of indefinite saddle point forms   We obtain sufficient conditions that ensure block diagonalization (by a
direct rotation) of sign-indefinite symmetric sesquilinear forms as well as the
associated operators that are semi-bounded neither from below nor from above.
In the semi-bounded case, we refine the obtained results and, as an example,
revisit the block Stokes Operator from fluid dynamics.

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The categories of this paper are: q-alg
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The categories of this paper are: hep-ph
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The categories of this paper are: alg-geom
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The categories of this paper are: hep-ex
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The categories of this paper are: ao-sci
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The categories of this paper are: acc-phys
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The categories of this paper are: mtrl-th
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The categories of this paper are: adap-org
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The categories of this paper are: supr-con
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The categories of this paper are: atom-ph
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The categories of this paper are: astro-ph
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The categories of this paper are: eess
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The categories of this paper are: nucl-th
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The categories of this paper are: solv-int
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The categories of this paper are: chao-dyn
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The categories of this paper are: quant-ph