@techreport{R-91-01, TITLE = {A Simple Fixed Point Characterization of Three-valued Stable Model Semantics}, AUTHOR = {Staffan Bonnier and Ulf Nilsson and Torbj{\"o}rn N{\"a}slund}, YEAR = {1991}, NUMBER = {R-91-01}, INSTITUTION = ida, ADDRESS = idaaddr, ABSTRACT = {}, IDANR = {LiTH-IDA-R-91-01}, NOTE = {Also accepted for publication in Processing Letters}