Keys paper

Here is the other keys paper I mentioned.

Ian

@InProceedings{CaDL00b,
  author =       "Diego Calvanese and De Giacomo, Giuseppe and
                  Maurizio Lenzerini",
  title =        "Keys for Free in Description Logics",
  booktitle =    DL-00,
  pages =        "79--88",
  year =         2000,
  publisher =    "CEUR Electronic Workshop Proceedings,
                  \url{http://ceur-ws.org/Vol-33/}",
}