Ugo Galassi Attilio Giordana Lorenza Saitta Incremental Construction of Structured Hidden Markov Models. 798-803 2007 conf/ijcai/2007 IJCAI http://dli.iiit.ac.in/ijcai/IJCAI-2007/PDF/IJCAI07-128.pdf db/conf/ijcai/ijcai2007.html#GalassiGS07