On Jan 11, 2009, at 10:18 AM, Pat Hayes wrote:
When you say “Those various temporal theories can all be expressed in terms of three concepts: time-point, time-interval and duration.” , what do you mean by that? Is being “expressed in terms of” used only for necessary and sufficient definitions?
No, I mean only that each theory uses only those three terms, or can be reformulated using only those (or in some cases only two of them.) Of course, since the theories have different axioms, they assign somewhat different meanings to them.
Thinking more, this isn't really accurate. They all use only these three classes, but they also use various different relations, such as the timepoint and subinterval orderings and the various relations between points and intervals. So perhaps the typical number of concepts is more like six or seven than two or three.