@inproceedings{BKV04,
	author	    =   "D. Bustan and O. Kupferman and M.Y. Vardi",
        title       =   "A Measured Collapse of The Modal $\mu$-Calculus Alternation Hierarchy",
        booktitle   =   "Proc. 21st Symp. on Theoretical Aspects 
                         of Computer Science",
        series      =   "Lecture Notes in Computer Science",
        volume	    =   "",
        pages       =   "",
        publisher   =   "Springer-Verlag",
        year        =   "2004"
}