Why Does Propositional Quantification Make Modal and Temporal Logics on Trees Robustly Hard?

Adding propositional quantification to the modal logics K, T or S4 is known to lead to undecidability but CTL with propositional quantification under the tree semantics (tQCTL) admits a non-elementary Tower-complete satisfiability problem. We investigate the complexity of strict fragments of tQCTL a...

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Main Authors: Bartosz Bednarczyk, Stéphane Demri
Format: Article
Language:English
Published: Logical Methods in Computer Science e.V. 2022-07-01
Series:Logical Methods in Computer Science
Subjects:
Online Access:https://lmcs.episciences.org/7409/pdf
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author Bartosz Bednarczyk
Stéphane Demri
author_facet Bartosz Bednarczyk
Stéphane Demri
author_sort Bartosz Bednarczyk
collection DOAJ
description Adding propositional quantification to the modal logics K, T or S4 is known to lead to undecidability but CTL with propositional quantification under the tree semantics (tQCTL) admits a non-elementary Tower-complete satisfiability problem. We investigate the complexity of strict fragments of tQCTL as well as of the modal logic K with propositional quantification under the tree semantics. More specifically, we show that tQCTL restricted to the temporal operator EX is already Tower-hard, which is unexpected as EX can only enforce local properties. When tQCTL restricted to EX is interpreted on N-bounded trees for some N >= 2, we prove that the satisfiability problem is AExpPol-complete; AExpPol-hardness is established by reduction from a recently introduced tiling problem, instrumental for studying the model-checking problem for interval temporal logics. As consequences of our proof method, we prove Tower-hardness of tQCTL restricted to EF or to EXEF and of the well-known modal logics such as K, KD, GL, K4 and S4 with propositional quantification under a semantics based on classes of trees.
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spelling doaj.art-cff7fc40bfd748a49de92c46013f4a802024-03-08T10:39:29ZengLogical Methods in Computer Science e.V.Logical Methods in Computer Science1860-59742022-07-01Volume 18, Issue 310.46298/lmcs-18(3:5)20227409Why Does Propositional Quantification Make Modal and Temporal Logics on Trees Robustly Hard?Bartosz Bednarczykhttps://orcid.org/0000-0002-8267-7554Stéphane DemriAdding propositional quantification to the modal logics K, T or S4 is known to lead to undecidability but CTL with propositional quantification under the tree semantics (tQCTL) admits a non-elementary Tower-complete satisfiability problem. We investigate the complexity of strict fragments of tQCTL as well as of the modal logic K with propositional quantification under the tree semantics. More specifically, we show that tQCTL restricted to the temporal operator EX is already Tower-hard, which is unexpected as EX can only enforce local properties. When tQCTL restricted to EX is interpreted on N-bounded trees for some N >= 2, we prove that the satisfiability problem is AExpPol-complete; AExpPol-hardness is established by reduction from a recently introduced tiling problem, instrumental for studying the model-checking problem for interval temporal logics. As consequences of our proof method, we prove Tower-hardness of tQCTL restricted to EF or to EXEF and of the well-known modal logics such as K, KD, GL, K4 and S4 with propositional quantification under a semantics based on classes of trees.https://lmcs.episciences.org/7409/pdfcomputer science - logic in computer science
spellingShingle Bartosz Bednarczyk
Stéphane Demri
Why Does Propositional Quantification Make Modal and Temporal Logics on Trees Robustly Hard?
Logical Methods in Computer Science
computer science - logic in computer science
title Why Does Propositional Quantification Make Modal and Temporal Logics on Trees Robustly Hard?
title_full Why Does Propositional Quantification Make Modal and Temporal Logics on Trees Robustly Hard?
title_fullStr Why Does Propositional Quantification Make Modal and Temporal Logics on Trees Robustly Hard?
title_full_unstemmed Why Does Propositional Quantification Make Modal and Temporal Logics on Trees Robustly Hard?
title_short Why Does Propositional Quantification Make Modal and Temporal Logics on Trees Robustly Hard?
title_sort why does propositional quantification make modal and temporal logics on trees robustly hard
topic computer science - logic in computer science
url https://lmcs.episciences.org/7409/pdf
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