John, you clearly have an overall vision for the SWeb, a passion for promoting
it, and energy to spare. Why then are you haranguing *us*, in *this* forum? We
have no influence over SWeb standards. Why aren't you proposing to the W3C to
set up a working group (or better still, setting up the group and then
proposing to the W3C that y'all do whatever it is that you think needs to be
done)? Just writing a W3C "note" (which has no normative content and so can be
published fairly freely) would be a way to get things started: if enough people
rally to your flag, you have the beginnings of a working group and a nascent
community of users right there. (01)
Pat (02)
On Nov 20, 2012, at 9:35 AM, John F Sowa wrote: (03)
> Ed, Chris, Amanda, Doug, and Rich,
>
> I'll start by emphasizing that I have no objection to anyone
> developing or using any tools or notations they find useful. My
> primary objection to what became of the Semantic Web is the loss
> of most of the goals stated in Tim B-L's original DAML proposal.
>
> The three terms Tim emphasized were diversity, heterogeneity, and
> interoperability. All of them disappeared from the final DAML report.
> Even tools that had been developed to use RDF and OWL, such as SWRL
> and RuleML, were omitted or deprecated.
>
> The letter A in DAML is for Agents. To express messages among
> heterogeneous agents, Tim proposed SWeLL (Semantic Web Logic Language)
> as a superset of propositional, first-order, and higher-order logic.
> SWeLL required high expressive power to accommodate everything that
> could be expressed in any or all of the languages and systems cited.
>
> The insistence on decidability is incompatible with heterogeneity.
> But some of the most efficient implementations translate OWL to Prolog,
> which is undecidable. Some people may claim that Prolog includes
> procedural features that are outside logic. But there are many other
> logic-based approaches that have been ignored. For example, see
>
> http://www.hassan-ait-kaci.net/pdf/osf4sw.pdf
> A Sorted-Graph Unification Approach to the Semantic Web
>
> What I am arguing *for* is the diversity that Tim emphasized and
> cited in his original proposal, the diversity among the 22 groups
> that were supposedly included in the DAML project, the wide range
> of R & D that has been done since 2005, and *most* importantly,
> seamless integration with the tools and notations of mainstream IT.
>
> JFS
>>> Note that a procedure can be decidable for some data, but
>>> undecidable for other data.
>
> EB
>> Right. So a desirable procedure should be decidable on all the data
>> it will be asked to process. No one cares whether one can write
>> undecidable programs in the language.
>
> Yes, but I'd add some qualifications. FOL has a large number of
> complexity classes, many of which can be distinguished by simple
> syntactic checks on the data and/or the axioms about the data. Cyc,
> for example, perform such checks to see which procedure(s) to use.
>
> Since most systems today have multiple CPUs, some systems start
> a "horse race" among several procedures, pick the one(s) that
> finish early, and stop the others. IBM's Watson with 2880 CPUs
> uses this approach heavily.
>
> EB
>> Industry has been using logics for the (b)/(c) cases for at least 25
>> years, and we now know a lot about the relationships between reasoning
>> algorithms, base theories, and decidability and computational bounding.
>> Almost all of the logics used for (b)/(c) are constrained FOLs or "not
>> FOL", and almost all of the algorithms used with these logics are
>> computationally bounded. That is why they are commonly used in industry.
>
> There are many complex reasons, and they keep changing with the kinds
> of technology available. My main point is that any one-size-fits-all
> solution is going to be wrong for many important applications.
>
> EB
>> The problem of not knowing the relationship between input
>> data -- the sets of valid sentences -- and the "not determinable"
>> result is what causes industry to shy away from FOL reasoners.
>
> DF
>> We devised a system that could guarantee that the combined algorithm
>> would produce a valid answer when that answer was needed (a variable
>> amount of time with a minimum value), but could normally calculate a
>> better answer through heuristic calculations.
>
> I also cite the paper by Bill Andersen et al., in which they developed
> a knowledge compiler that translates axioms expressed in CycL (a highly
> expressive superset of FOL) into Horn-clause rules for an inference
> engine and into SQL constraints for a relational DB. That was the
> R & D that led them to found OntologyWorks (now HighFleet). For
> discussion of that approach (and others), see page 6 of
>
> http://www.jfsowa.com/pubs/fflogic.pdf
>
> OntologyWorks took a while to build up the business, but HighFleet
> now gets more business than they can handle.
>
> CMungal
>> I just want to point out that Ian Horrocks has developed reasoners
>> such as FaCT which count as application programs. His group develops
>> the HermiT and ELK reasoners which we use every day in the development
>> of the Gene Ontology (as well as numerous other biological ontologies).
>
> I'm glad that Ian is doing something useful. But a reasoner, by itself,
> is not an application program.
>
> FOL is actually easier for humans to read and write than OWL DL.
> And it can be stated in controlled NLs. A knowledge compiler can
> translate FOL to whatever format is needed for whatever reasoning
> engine and database is used.
>
> AV
>> The real valuable work comes from identifying logic languages and procedures
>> that maximize expressiveness, usability, and reasoning within the domain
>> of statements and tasks the user needs. That is more complex and subtle.
>> There are lots of ways to design systems to either disallow certain
>> statements (IMHO, better done semantically than via unusably counter-
>> intuitive or restricted syntax), or decline to process certain reasoning
>> patters that have a high rabbit-hole risk, or cut out after a certain time,
>> or use other techniques to tune performance. The line between decidable and
>> undecidable systems is not a sweet spot for this.
>
> I very strongly agree.
>
> RC
>> Constraint propagation is another example of something you can't usually
>> do in a program with a tree structured design; it requires that the
>> program investigate constraint sets that are cross coupled. Constraints
>> that are not cross coupled are not very useful
>
> Yes. That is another problem with OWL. No OWL ontology can specify
> any structure that is not tree. You can't specify the constraints
> of a triangle or a bridge truss built up of multiple triangles.
>
> AV
>> ... by "a guaranteed finite-time result," I meant "a result guaranteed
>> to come with an unknown, but finite, amount of time. That's the guarantee
>> that comes with "decidable" and is of little-to-no value in deployed
>> applications.
>
> Yes, indeed. NP complete algorithms are decidable, but they can take
> more time than the age of the universe. That's not useful.
>
> EB
>> John Sowa originally wrote that no user asks for decidability, users
>> always ask for more expressiveness. I have yet to hear a user ask for
>> either. Industry users are interested in capability and performance.
>
> I was quoting Bob MacGregor. His users were familiar with DL systems,
> since PowerLOOM included a DL reasoner as one component. But I agree
> with the final sentence.
>
> AV
>>> The line between decidable and undecidable systems is not
>>> a sweet spot for this.
>
> EB
>> But the line between DLs and FOLs *is* a sweet spot for this.
>
> No. The sweet spot for OWL is the subset used by GoodRelations and
> adopted by Schema.org. They ignored all other features of OWL.
>
> For that subset, there are superfast algorithms that can generate
> a consistent type hierarchy (actually a lattice) automatically.
> For example, see the home page for Formal Concept Analysis (FCA):
>
> http://www.upriss.org.uk/fca/fca.html
>
> In fact, FCA tools are also used to check an OWL hierarchy for
> consistency or even to generate the OWL hierarchy automatically.
> For details, type "FCA OWL concept" to your favorite search engine.
>
> DF
>> A multiple-method system is often the best performer. The overwhelming
>> majority of systems I see, read about, or hear about attempt to use a
>> single reasoning method to solving all problems. Whatever that method is,
>> it may perform well on some of the problems within the domain of use; it
>> often performs poorly on many others, or even rules out addressing them at
>> all.
>
> I very strongly agree.
>
> Recommendations:
>
> 1. Support the original DAML proposal for message passing in a highly
> expressive logic among multiple heterogeneous.
>
> 2. Don't reject any tools or notations that anyone has found useful.
> That includes all current SW tools. But even more important are
> all the legacy systems of mainstream IT and all the newly emerging
> research projects that may become the future mainstream.
>
> 3. Promote R & D on simplifying the interfaces and techniques for
> knowledge representation, acquisition, and use. We need tools
> with better human factors and with automatic generation of the
> formats required for reasoning. Better graphics, controlled
> natural languages, FCA, and knowledge compilation are examples.
>
> 4. A smooth migration path from the tools and methodologies of
> mainstream IT to the new technology is essential. UML diagrams,
> for example, are already integrated with mainstream IT. They
> can be added to the Schema.org vocabularies to support a superset
> of what can be specified in OWL, but in a humanly readable form
> that is already familiar to most programmers.
>
> Much more can be said, but this would be a good start. It would
> support much more of Tim's original vision for the SW, and it
> would help bring ontologies into the mainstream.
>
> John
>
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