| Popis: |
We wish to briefly discuss recent work in conceptual modelling from a slightly different point of view in order to highlight the parallels between data and transactions, and then mention some benefits of this view.A time-honoured way of describing a system (portion of the world) is by positing a domain of objects and then inter-relating them through function and predicate symbols. The resulting description is a set of axioms in a FOPC. If the world is dynamic, one usually augments the description with the notion of time or state, in which case axioms can be divided naturally into “general laws” (heretofore constraints) holding in all states, and state-specific “facts”. Given states, one then also has the ability to describe state transitions (events) as predicates on pairs of states or, as shown below, as objects in their own right. |
