Reference Constraints and Individual Level Inheritance

. Equality constraints partition logical variables into coreference classes, each of which denotes an individual (which may be unspecified or partially specified) in a domain of discourse. These classes, however, are unrelated to each other. We propose reference constraints as a generalization of equality constraints, allowing the specification of a partial ordering among coreference classes. This leads to the notion of individual level inheritance, where an individual denoted by a variable may inherit properties from another individual which is denoted by a subsuming variable in the partial order. A variety of systems, especially systems reasoning in ambiguous domains, would benefit from an efficient, formally based implementation of reference constraints and individual level inheritance. 1 Introduction Sort hierarchies (partial orders defined on sorts) play an important role in manysorted logics [7]. In object-oriented [6] and logic [2] programming, they are fundamental for the imp..