@booklet {malenfant91coherent,
	title = {Coherent State Changes in Logic Programs},
	number = {RXF},
	year = {1991},
	publisher = {Institut Blaise Pascal, Universit{\'e} Paris VI-VII},
	type = {Rapport LITP 91-01},
	author = {J. Malenfant and Guy Lapalme and Vaucher, J.}
}
