Query Learning of Regular Tree Languages: How to Avoid Dead States.

Frank Drewes Johanna Högberg Query Learning of Regular Tree Languages: How to Avoid Dead States. 163-185 2007 40 Theory Comput. Syst. 2 http://dx.doi.org/10.1007/s00224-005-1233-3 db/journals/mst/mst40.html#DrewesH07