Dear John,
As you say many steps and bridges are needed for formal methods to become
part of everyday engineering. As to what logic to use, it is certainly the
case that DLs are insufficient, including OWL for engineering purposes. This
applies to Steve Ray's list. However DL constructions are an extremely good
way to express various necessary conditions for systems. I understand
Matthew's background with Express. My choice of logic, as you can see from a
diagram in the paper is type theory such as developed by Lambek and Scott.
This is a version of higher order logic in that it has terms which from a
full higher order logic. It can be expressed as a deduction system and as a
FOL theory with a rich type structure. I also developed and implemented a
type theory logic around the same time which was derived from Lawvere's FOL
axioms for a topos. It was called Algos. I have been able to embed large
parts of SysML into this version of type theory.
- Henson (01)
-----Original Message-----
From: ontology-summit-bounces@xxxxxxxxxxxxxxxx
[mailto:ontology-summit-bounces@xxxxxxxxxxxxxxxx] On Behalf Of John F. Sowa
Sent: Wednesday, February 22, 2012 7:25 AM
To: ontology-summit@xxxxxxxxxxxxxxxx
Subject: Re: [ontology-summit] Ontology Engineering for Systems Engineering (02)
On 2/22/2012 12:08 AM, henson graves wrote:
> With engineering languages such as UML and SysML (a UML dialect for
> engineering) engineers can and do develop the designs for very complex
> systems. These languages work in practice. There is a lot of evidence
> for this. I have a lot of experience with using the languages to build
> and analyze complex systems. I enclose one paper on this topic; it
> points to other more technical papers. (03)
Thanks for the paper. I think that SysML is a good tool for system analysis
and design. Engineers and programmers find such diagrams valuable aids for
visualizing complex relationships. I believe that they can be an important
piece of the puzzle. (04)
> The fact that a language such as SysML works is a relatively new
> development. Their predecessors did not work until after year 2000.
> There are very specific "ontological" reasonswhy the predecessors did
> not work and the more recent ones do work. (05)
When you adapt a tool from one discipline to another there is always a need
to tailor the terminology and methodology to the new requirements.
But I would add that ontology has used diagrams for centuries. The Tree of
Porphyry (third century AD) established the conventions for type hierarchies
that were used in textbooks since the middle ages.
The UML and SysML type hierarchies are based on the same principles. (06)
> Engineers, not the AI or ontology folks, are the ones who have
> discovered good terminological primitives for building system
> representations. (07)
Anybody who needs a bridge should hire an engineer, not a physicist
-- but make sure that you hire a civil engineer, not a chemical engineer, an
electrical engineer, or a sanitary engineer. (08)
> So to summarize I am pretty confident that the integration of formal
> methods into everyday engineering practice will happen in due course. (09)
I agree, but there are many intermediate steps that must be accomplished
along the way. Diagrams can be a very useful bridge between human- oriented
tools and formal logic. But we also need to build bridges between formal
logic and the software that drives engineering systems, financial systems,
and the World Wide Web (which is far, far bigger than just the Semantic
Web). (010)
I noticed that your paper talks a lot about Description Logics.
DLs are a fine tool for representing and reasoning about type hierarchies.
But the UML diagrams cover much more than DLs. (011)
In his engineering work, Matthew used Express, which is a practical
engineering tool that has the full expressive power of FOL. DLs are OK for
part of the problem, but SysML must support *everything* -- you can't do
that with just DLs. (012)
John (013)
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