@article{Loyer05,
	Author = {Loyer, Yann and Straccia, Umberto},
	Journal = {Theoretical Computer Science},
	Number = {2-3},
	Pages = {351-381},
	Publisher = {Elsevier Science Publishers Ltd.},
	Title = {Any-World Assumptions in Logic Programming},
	Volume = {342},
	Year = {2005}}