IAB201 Lecture Notes - Lecture 2: Modeling Language, Arity, Subtyping
Document Summary
Two important aspects: a method to design a conceptual model should be powerful enough to express the necessary concepts to describe the universe of discourse (the domain) being modelled. What is information: data - items store in an info base (e. g. database) In a database, we are concerned with storing facts, i. e. , propositions which are held to be true in the universe of discourse (the domain). In the conceptual schema, we store the governing rules of those facts. Facts asset that objects play roles; hence the name object-role modelling. A predicate is a sentence template: e. g. Where the arity of predicate is greater than one, the predicate can be read in more than one way for instance: mary works in sales. Sales employs mary: e(cid:373)ploys is the i(cid:374)(cid:448)erse of (cid:449)orks i(cid:374) . These two predicates have different surface structures but the same deep structure: need to look at the deep structure to understand what we are dealing with.
