@inproceedings{ML-1989-Valtorta,
	author        = "Marco Valtorta",
	booktitle     = "{Proceedings of the Sixth International Workshop on Machine Learning}",
	isbn          = "1-55860-036-1",
	pages         = "326--331",
	publisher     = "{Morgan Kaufmann}",
	title         = "{Some Results on the Complexity of Knowledge-Based Refinement}",
	year          = 1989,
}