The modal mu-calculus alternation hierarchy is strict [chapter]

J. C. Bradfield
1996 Lecture Notes in Computer Science  
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. @ 1998 -Elsevier Science B.V. All rights reserved
doi:10.1007/3-540-61604-7_58 fatcat:rqvgzyzj3neo7f7rpt465s5iga