Focussing, MALL and the Polynomial Hierarchy

Anupam Das

    1 Citation (Scopus)

    Abstract

    We investigate how to extract alternating time bounds from ‘focussed’ proofs, treating non-invertible rule phases as nondeterministic computation and invertible rule phases as co-nondeterministic computation. We refine the usual presentation of focussing to account for deterministic computations in proof search, which correspond to invertible rules that do not branch, more faithfully associating phases of focussed proof search to their alternating time complexity. As our main result, we give a focussed system for MALLw (MALL with weakening) with encodings to and from true quantified Boolean formulas (QBFs): in one direction we encode QBF satisfiability and in the other we encode focussed proof search. Moreover we show that the composition of the two encodings preserves quantifier alternation, yielding natural fragments of MALLw complete for each level of the polynomial hierarchy. This refines the well-known result that MALLw is PSPACE-complete.

    Original languageEnglish
    Title of host publicationAutomated reasoning : 9th International Joint Conference, IJCAR 2018 Held as Part of the Federated Logic Conference, FloC 2018 Oxford, UK, July 14–17, 2018 Proceedings
    EditorsDidier Galmiche, Stephan Schulz, Roberto Sebastiani
    PublisherSpringer
    Publication date30 Jun 2018
    Pages689-705
    Chapter45
    ISBN (Print)978-3-319-94204-9
    ISBN (Electronic)978-3-319-94205-6
    DOIs
    Publication statusPublished - 30 Jun 2018
    Event9th International Joint Conference on
    Automated Reasoning
    - Oxford, United Kingdom
    Duration: 14 Jul 201817 Jul 2018

    Conference

    Conference9th International Joint Conference on
    Automated Reasoning
    Country/TerritoryUnited Kingdom
    CityOxford
    Period14/07/201817/07/2018
    SeriesLecture Notes in Computer Science
    Volume10900
    ISSN0302-9743

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