@article {DBLP:journals/amai/PedreschiS97, title = {Non-determinism in Deductive Databases - Preface}, journal = {Ann. Math. Artif. Intell.}, volume = {19}, number = {1-2}, year = {1997}, pages = {1-2}, author = {Dino Pedreschi and V. S. Subrahmanian} }