Language Independence and Language Tolerance in Logic Programs

The consequences of a logic program depend in general upon both the rules of the program and its language. However the consequences of some programs are independent of the choice of language, while others depend on the language of the program in only a restricted way. In this paper, we deene notions of language independence and language tolerance corresponding to these two cases. Furthermore, we show that there are syntactically-deened classes of programs that are language independent and language tolerant. A primary application of these results is to guarantee that for some programs it is permissible to ignore the fact that the language of the program is many-sorted. This is useful to know, since query evaluation procedures generally take no account of sorts.