Regular expression transformations to extend regular languages (with application to a Datalog XML schema validator).

Robson da Luz Mirian Halfeld Ferrari Alves Martin A. Musicante Regular expression transformations to extend regular languages (with application to a Datalog XML schema validator). 148-167 2007 62 J. Algorithms 3-4 http://dx.doi.org/10.1016/j.jalgor.2007.04.004 db/journals/jal/jal62.html#LuzAM07