@inproceedings{STOC-1980-Fagin,
	author        = "Ronald Fagin",
	booktitle     = "{Proceedings of the 12th Annual ACM Symposium on Theory of Computing}",
	doi           = "10.1145/800141.804660",
	pages         = "123--134",
	publisher     = "{ACM}",
	title         = "{Horn Clauses and Database Dependencies}",
	year          = 1980,
}