Efficient asymmetric inclusion between regular expression types.

Dario Colazzo Giorgio Ghelli Carlo Sartiani Efficient asymmetric inclusion between regular expression types. 174-182 2009 ICDT http://doi.acm.org/10.1145/1514894.1514916 conf/icdt/2009 db/conf/icdt/icdt2009.html#ColazzoGS09