@inproceedings{GroheKreSch05,
  abstract = "The present paper gives a classification of the expressive power of two-variable least fixed-point logics. The main results are: <br /><ol><li> The two-variable fragment of monadic least fixed-point logic with parameters is as expressive as full monadic least fixed-point logic (on binary structures). </li><li> The two-variable fragment of <i>monadic</i> least fixed-point logic without parameters is as expressive as the two-variable fragment of <i>binary</i> least fixed-point logic without parameters. </li><li> The two-variable fragment of binary least fixed-point logic with parameters is strictly more expressive than the two-variable fragment of monadic least fixed-point logic with parameters (even on finite strings). </li></ol>",
  author = "M. Grohe and S. Kreutzer and N. Schweikardt",
  booktitle = "Symposium on Mathematical Foundations of Computer Science (MFCS)",
  pages = "422 -- 434",
  publisher = "Springer",
  series = "Lecture Notes in Computer Science",
  title = "The Expressive Power of Two-Variable Least Fixed-Point Logics",
  url = "http://web.comlab.ox.ac.uk/oucl/work/stephan.kreutzer/Publications/05-mfcs.pdf",
  year = "2005",
}