IAB201 Lecture Notes - Lecture 4: Arity, Subtyping
Document Summary
What"s wrong with this model: try to combine entity types whenever possible. If you store derivable information, then: you are storing unnecessary data, you can give incorrect results when the base facts alter. It is optimal to let the computer calculate derivable information. Step 1: transform familiar examples into elementary facts, and apply quality checks. Step 2: draw the fact types, and apply a population check. Step 3: check for entity types to be combined, and note any arithmetic derivations. Step 4: add uniqueness constraints, and check the arity (length) of fact types. Step 5: add mandatory role constraints, and check for logical derivations. Step 6: add value, set-comparison and subtyping constraints. Step 7: add other constraints and perform final checks. The rest of the cdsp is concerned with specifying constraints: uniqueness, mandatory role, set comparison, etc. Each base fact type must assign at least one uc.
