@ARTICLE {
	AUTHOR = "Pablo Barcel{\'o} and Andreas Pieris and Miguel Romero",
	TITLE ="Semantic Optimization in Tractable Classes of Conjunctive Queries",
	JOURNAL = "SIGMOD Record",
	VOLUME = "46",
	NUMBER = "2",
	PAGES = "5-17",
	MONTH = "Jun",
	YEAR = "2017",
	PUBLISHER = "ACM Press",
	ADDRESS = "New York, NY, USA",
	ISSN = "0163-5808"
	}