@inproceedings{PPDP-2006-GabbayM,
	author        = "Murdoch Gabbay and Aad Mathijssen",
	booktitle     = "{Proceedings of the Eighth International Conference on Principles and Practice of Declarative Programming}",
	doi           = "10.1145/1140335.1140359",
	isbn          = "1-59593-388-3",
	pages         = "189--200",
	publisher     = "{ACM}",
	title         = "{One-and-a-halfth-order logic}",
	year          = 2006,
}