Logical Methods in Computer Science (Dec 2021)

A Probabilistic Higher-order Fixpoint Logic

  • Yo Mitani,
  • Naoki Kobayashi,
  • Takeshi Tsukada

DOI
https://doi.org/10.46298/lmcs-17(4:15)2021
Journal volume & issue
Vol. Volume 17, Issue 4

Abstract

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We introduce PHFL, a probabilistic extension of higher-order fixpoint logic, which can also be regarded as a higher-order extension of probabilistic temporal logics such as PCTL and the $\mu^p$-calculus. We show that PHFL is strictly more expressive than the $\mu^p$-calculus, and that the PHFL model-checking problem for finite Markov chains is undecidable even for the $\mu$-only, order-1 fragment of PHFL. Furthermore the full PHFL is far more expressive: we give a translation from Lubarsky's $\mu$-arithmetic to PHFL, which implies that PHFL model checking is $\Pi^1_1$-hard and $\Sigma^1_1$-hard. As a positive result, we characterize a decidable fragment of the PHFL model-checking problems using a novel type system.

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