Mark and Dick, (01)
MHL
> I WISH that the SBVR designers had chosen to define it in terms
> of a system with a sound semantic basis, such as CL/IKL. (02)
The failure to start with a sound semantic basis has plagued computer
systems for years. I blame both the programmers and the logicians.
Their excuses are stated in many different ways, but the reason is
always the same: they don't understand each other's point of view. (03)
MHL
> Ed and I and the Date-Time Vocabulary (DTV) team chose to define
> key aspects of DTV in CL + IKL, and in UML + OCL, partly to ensure
> a firm semantic foundation for our work. (04)
That's good. But there have been many good examples like that over
the years, and the next group of designers never learn the lesson. (05)
Ted Codd started with logic as a foundation for RDBs. The SQL
WHERE-clause can be used to represent FOL, but in a way that I used
to call the worst notation for logic ever invented. Datalog is an
excellent query and constraint language for any DB (relational or
graph based). But there are many turf battles over doing anything
to simplify and standardize DBs. (06)
For the Semantic Web, Tim B-L proposed a foundation called SWeLL
(Semantic Web Logic Language) in 2000. Pat Hayes and Guha developed
a logic called SWEL for specifying RDF -- with a semantics that was
almost identical to CL. But the OWL gang wanted their own model
theory, and most of the voters in the W3C were clueless about any
issue that was related to logic. (07)
Fundamental problem: Most programmers don't understand how simple logic
really is, and most logicians don't know how to explain logic to anyone
who doesn't already speak their language. For a simpler intro, see (08)
http://www.jfsowa.com/talks/egintro.pdf (09)
MHL
> What I meant is that the "that" operator (in whatever semantic system /
> language) is necessary for adequately capturing important aspects of real
> business rules and vocabularies. (010)
I agree. Note slide 4 of egintro.pdf, which shows Peirce's version. (011)
RHM
> John Sowa's earlier remarks about IKL and "that" identified the
> fundamental issue underlying this entire thread. The details relating
> to graphs and triples are not important. What's important is the
> treatment of propositions and sentences (using John's terms). I will
> simply use the term proposition. (012)
I'm glad that we can agree on something. But the same proposition
can be expressed by different sentences. Note slides 8 to 11 of
egintro.pdf. When you're trying to relate multiple notations, it's
essential to distinguish the readable mark (sentence) from the
meaning of the mark (proposition). (013)
In the following note, I define a proposition as an equivalence class
of sentences that can be mapped from one to the other by a meaning-
preserving translation (MPT): http://www.jfsowa.com/logic/proposit.htm (014)
John (015)
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