The Limit of Recursion in State-based Systems

Fuente: arXiv
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Main Authors: Afshari, Bahareh, Barlucchi, Giacomo, Leigh, Graham E.
Format: Preprint
Published: 2025
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author Afshari, Bahareh
Barlucchi, Giacomo
Leigh, Graham E.
author_facet Afshari, Bahareh
Barlucchi, Giacomo
Leigh, Graham E.
contents We prove that omega^2 strictly bounds the iterations required for modal definable functions to reach a fixed point across all countable structures. The result corrects and extends the previously claimed result by the first and third authors on closure ordinals of the alternation-free mu-calculus in [3]. The new approach sees a reincarnation of Kozen's well-annotations, devised for showing the finite model property for the modal mu-calculus. We develop a theory of 'conservative' well-annotations where minimality of annotations is guaranteed, and isolate parts of the structure that locally determine the closure ordinal of relevant formulas. This adoption of well-annotations enables a direct and clear pumping process that rules out closure ordinals between omega^2 and the limit of countability.
format Preprint
id arxiv_https___arxiv_org_abs_2511_02594
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle The Limit of Recursion in State-based Systems
Afshari, Bahareh
Barlucchi, Giacomo
Leigh, Graham E.
Logic in Computer Science
F.4.1
We prove that omega^2 strictly bounds the iterations required for modal definable functions to reach a fixed point across all countable structures. The result corrects and extends the previously claimed result by the first and third authors on closure ordinals of the alternation-free mu-calculus in [3]. The new approach sees a reincarnation of Kozen's well-annotations, devised for showing the finite model property for the modal mu-calculus. We develop a theory of 'conservative' well-annotations where minimality of annotations is guaranteed, and isolate parts of the structure that locally determine the closure ordinal of relevant formulas. This adoption of well-annotations enables a direct and clear pumping process that rules out closure ordinals between omega^2 and the limit of countability.
title The Limit of Recursion in State-based Systems
topic Logic in Computer Science
F.4.1
url https://arxiv.org/abs/2511.02594