Explaining SLDNF resolution with non-normal defaults

This paper defines a default logic interpretation for normal programs that has the following major characteristics. First, it directly captures the true nature of SLDNF resolution as an extension of SLD resolution. Second, it is semantically convincing, but it requires neither an elaborated nonstandard interpretation nor a radical rewriting of the program clauses that would make it difficult to understand their meaning. Last, it extends known results for stratified normal programs to programs that satisfy a weaker condition.