Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Alternation Is Strict For Higher-Order Modal Fixpoint Logic   We study the expressive power of Alternating Parity Krivine Automata (APKA),
which provide operational semantics to Higher-Order Modal Fixpoint Logic (HFL).
APKA consist of ordinary parity automata extended by a variation of the Krivine
Abstract Machine. We show that the number and parity of priorities available to
an APKA form a proper hierarchy of expressive power as in the modal
mu-calculus. This also induces a strict alternation hierarchy on HFL. The proof
follows Arnold's (1999) encoding of runs into trees and subsequent use of the
Banach Fixpoint Theorem.

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The categories of this paper are: supr-con
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The categories of this paper are: physics
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The categories of this paper are: gr-qc
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The categories of this paper are: cond-mat
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The categories of this paper are: dg-ga
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The categories of this paper are: hep-ph
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The categories of this paper are: patt-sol
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The categories of this paper are: math-ph
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The categories of this paper are: nucl-ex
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The categories of this paper are: comp-gas
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The categories of this paper are: chao-dyn
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The categories of this paper are: hep-th
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The categories of this paper are: nucl-th
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The categories of this paper are: nlin
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The categories of this paper are: plasm-ph
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The categories of this paper are: alg-geom