@InProceedings{ dix91cumulativity, author = {J\"{u}rgen Dix}, title = {{C}umulativity and {R}ationality in {S}emantics of {N}ormal {L}ogic {P}rograms}, booktitle = {Proceedings of the first Workshop on Nonmonotonic and Inductive Logic 1990 in Karlsruhe}, year = {1991}, editor = {J. Dix and K. P. Jantke and P. H. Schmitt}, pages = {13--37}, series = {LNCS 543}, publisher = {Springer}, address = {Berlin}, month = {October} }