Event, Property and Hierarchy in Order-Sorted Logic
Ken Kaneiwa, SATOSHI TOJO · The MIT Press eBooks · 1999
Knowledge representation in logics, even in the order-sorted logic that includes a sort hierarchy, tends to lose the conciseness and the nuances of natural language. If we could construct a logic that includes both predicates and terms as classes in the hierarchies, it would be very useful for connecting general knowledge to speci c knowledge. Although there are actually logics that are equipped with such a predicate hierarchy, they are built by logical implication and they cause the problem of predicate uni cation between di erent argument structures. In this paper, we present a logic language with a class hierarchy of predicates, where in the uni cation of predicates we devise a mechanism for deriving superordinate predicates in the hierarchy and for quantifying supplementary arguments. The arguments are quanti ed di erently, depending on whether a predicate is interpreted as an occurrence of an event or a universal property. Thus, we include the distinction between events and properties in predicates and present a logic language that can exibly relate predicates with di erent argument structures. We formalize the logic language both by syntax and semantics, and develop the inference system. 1.