Ed, (01)
I think that the major differences are the result of different
assumptions and definitions. (02)
EB:
> ... A certain major vendor failed to support
> the standards candidacy of a conceptual schema language created by one
> its elves in the woods, even though it had some commercial following.
> Another vendor actively blocked a standards effort that threatened to
> standardize NIAM, because it had the only commercial tooling for the
> language at the time. As late as 2004, the responsible authors of a
> widely used information modeling language (other than UML) refused to
> allow the surface language to be standardized, opting only for a
> conceptual metamodel. In short, standards projects for conceptual
> schema languages failed because the authors of the candidate languages
> wanted to retain ownership of them. (03)
My (personal) goal had always been to focus on the semantics in a form
that could support any and every special-purpose notation. When I
first started attending the X3H4 meetings, I was working at IBM, and
I avoided any statements that conflicted with official IBM policy. (04)
But when I participated in the conceptual schema subgroup, I was
actively proposing a logic-based semantics in a form that could
support any and every vendor's syntax. In 1992, I persuaded
Mike Genesereth and Richard Fikes (the authors of the KIF report)
to attend the SC32 meeting in Florida to begin a project on
developing parallel standards for KIF and conceptual graphs. (05)
In another room at the same meeting, the Z gang was beginning their
work on an ISO standard for Z notation. However, Z is a strongly
typed version of logic, which is more restricted than KIF or CGs.
It was easier to adopt a common semantics for KIF and CGs -- but Z
could be supported by a restricted subset of the KIF-CG semantics. (06)
EB:
> BTW, I don't want that to sound pejorative. It was, after all, their
> intellectual property. (07)
I'd be happy to support anybody's private notation, but I'd prefer
to do so with as general and unencumbered a semantics as possible.
I would make the semantics (with a notation like CLIF or CGIF)
the standard, and let people translate it to whatever they like. (08)
EB:
> are you disagreeing with the assertion that the translation is
> difficult/impossible? (09)
The question is translation from what to what. To translate any
of the popular ontology/modeling languages to Common Logic (or
the IKL extension) is neither difficult nor impossible. In fact,
it's hard to find any common notation that *cannot* be translated. (010)
But I would agree that translating one special-purpose notation
to another special-purpose notation may be difficult or impossible.
But if you translate both to CL, you can state rules in CL for
relating their common subsets and providing ways of accommodating
those aspects that don't have one-to-one translations. I discuss
the issues about "knowledge compilers" in the following article: (011)
http://www.jfsowa.com/pubs/fflogic.pdf
Fads and fallacies about logic (012)
> The main difference, however, is that these conceptual schema
> languages have a semantic model based on a closed world assumption
> -- that the information base is a 'model', not just the rest of
> the ontology -- and in most cases they have some intrinsic notions
> that are non-monotonic. (013)
There are many different, but related ways of handling non-monotonic
and the CW and OW assumptions. My recommended version is one that
Alan Robinson (and others) proposed many years ago: treat them
as theory revision methods. See below for an explanation. (014)
EB:
> [The ANSI/SPARC conceptual schema] was a technical architecture
> for database specification. All the rest is window dressing. (015)
Some DB people had a very narrow view, but many others had a much
broader view. During the 1980s, I participated in an IFIP working
group on databases chaired by Robert Meersman. That group included
some dedicated logicians and AI people, and we organized a series of
conferences on Data Semantics that invited speakers like Dana Scott,
John McCarthy, Ray Reiter (and even me). Many people in that group
participated in writing the 1987 ISO report on the conceptual schema. (016)
JFS:
>> No matter how big the upper level may be, it can only contribute
>> a small part of the total that is needed for any significant application. (017)
EB:
> I don't know whether we agree here or not. If the application ontology
> is the "lower level", then it can be pretty small. Most of those I have
> had to build have had about 150 classes and 300 properties. The problem
> is that 120 of the 150 classes are primitive. (018)
That depends on how much of the semantics you intend to specify.
I have always maintained that a great deal of the semantics needed
for interoperability can be defined with a type hierarchy and very
few axioms. Two programs might use the same data in very different
ways, and neither one knows anything about what the other one does
with the data. (019)
EB:
> To make the ontology more useful, you need to produce definitions
> of most of the classes and properties, and that requires a much richer
> and clearly founded middle layer. I see my ontology as a hut with
> To make the ontology more useful, you need to produce definitions
> of most of the classes and properties, and that requires a much
> richer and clearly founded middle layer. I see my ontology as
> a hut with multiple levels of sub-basement. (020)
Yes. And all those levels for every application can require
a very large amount of specification that can overwhelm what
is in the hut. (021)
EB:
> My point was that the definition of conceptual schema in TR9007
> doesn't address the semantic interpretation or the expressiveness
> My point was that the definition of conceptual schema in TR9007
> doesn't address the semantic interpretation or the expressiveness
> of the language involved. And the definition of the content of
> the schema suggests that it needs an extremely powerful and
> My point was that the definition of conceptual schema in TR9007
> doesn't address the semantic interpretation or the expressiveness
> of the language involved. And the definition of the content of
> the schema suggests that it needs an extremely powerful and
> expressive language. (022)
Every major programming language is undecidable, and no programmer
would ever ask for a less expressive language. I discuss that and
related issues in the following article. (The editor of the journal
in which it appeared was Jim Hendler, who liked the article despite
the fact that we sometimes disagree about some things -- like OWL.): (023)
http://www.jfsowa.com/pubs/fflogic.pdf (024)
John
____________________________________________________________________ (025)
How to convert a proof in a non-monotonic logic to an equivalent
proof in a classical logic: (026)
1. Suppose that you have a default (or neg-as-failure) logic L
with a set of axioms A, divided into a subset A1 of classical
axioms and a subset A2 of default (or NEF) axioms. (027)
2. Any proof in L that uses no default axioms in A2 is identical
to the same proof in the corresponding classical logic that
uses only the classical axioms in A1. (028)
3. But suppose some steps of a proof P use N default axioms.
For each use of a default axiom in P, there is an assumption
d1, ..., dN that goes beyond the classical axioms in A1. (029)
4. That nonmonotonic proof P can then be considered equivalent
to a classical proof in a *revised* classical theory whose
axioms are the conjunction of A1 with d1, ..., dN. (030)
This equivalence between nonmonotonic logic and belief revision
(or theory revision) is discussed in many books and articles
about nonmonotonic reasoning. See, for example, (031)
Peppas, Pavlos (2008) Belief revision, in F. van Harmelen,
V. Lifschitz, & B. Porter, Handbook of Knowledge Representation,
Elsevier, Amsterdam, pp. 317-359. (032)
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