@article{Bradfield:TCS:1998,
    Abstract = {One of the open questions about the modal mu-calculus is whether the alternation hierarchy collapses; that is, whether all modal fixpoint properties can be expressed with only a few alternations of least and greatest fixpoints. In this paper, we resolve this question by showing that the hierarchy does not collapse.},
    Author = {Bradfield, Julian},
    ISSN = {0304-3975},
    Journal = {Theoretical Computer Science},
    Keywords = {mu-Calculus, Temporal logic, Expressivity, Fixpoints},
    Note = {Concurrency Theory},
    Number = {2},
    Pages = {133--153},
    Title = {The modal mu-calculus alternation hierarchy is strict},
    URL = {http://www.sciencedirect.com/science/article/pii/S030439759700217X},
    Volume = {195},
    Year = {1998},
    bdsk-url-1 = {http://www.sciencedirect.com/science/article/pii/S030439759700217X},
    bdsk-url-2 = {https://doi.org/10.1016/S0304-3975(97)00217-X},
    date-added = {2020-08-11 12:59:30 +0200},
    date-modified = {2020-08-11 13:00:34 +0200},
    doi = {10.1016/S0304-3975(97)00217-X}
}

@article{Bradfield:TCS:1998, Abstract = {One of the open questions about the modal mu-calculus is whether the alternation hierarchy collapses; that is, whether all modal fixpoint properties can be expressed with only a few alternations of least and greatest fixpoints. In this paper, we resolve this question by showing that the hierarchy does not collapse.}, Author = {Bradfield, Julian}, ISSN = {0304-3975}, Journal = {Theoretical Computer Science}, Keywords = {mu-Calculus, Temporal logic, Expressivity, Fixpoints}, Note = {Concurrency Theory}, Number = {2}, Pages = {133--153}, Title = {The modal mu-calculus alternation hierarchy is strict}, URL = {http://www.sciencedirect.com/science/article/pii/S030439759700217X}, Volume = {195}, Year = {1998}, bdsk-url-1 = {http://www.sciencedirect.com/science/article/pii/S030439759700217X}, bdsk-url-2 = {https://doi.org/10.1016/S0304-3975(97)00217-X}, date-added = {2020-08-11 12:59:30 +0200}, date-modified = {2020-08-11 13:00:34 +0200}, doi = {10.1016/S0304-3975(97)00217-X} }