On Oct 17, 2008, at 10:41 AM, Ed Barkmeyer wrote: (01)
> John F. Sowa wrote:
>> The folks who developed the Opera browser searched the WWW to
>> gather statistics about the percentage of web sites that adhere
>> to the W3C standards for HTML and XML. They found that only 4.13%
>> of the sites are standards compliant. Even more discouraging that
>> of those sites that have a logo claiming to comply with W3C
>> standards, only 50% were actually compliant. See
>>
>> http://arstechnica.com/news.ars/post/20081015-opera-study-only-4-13-of-the-
>> web-is-standards-compliant.html
>>
>> This should be a cautionary point for anybody who is proposing
>> to develop or use standards for ontology. Since a single
>> discrepancy can cause a theorem prover to collapse into
>> contradiction, it is important to design systems to expect
>> discrepancies.
>
> With all due respect, John, I think you are comparing apples and
> oranges.
>
> First, we have to recognize that three factors contribute to a lot of
> invalid HTML:
> - the design of the browsers, and toolkits that enable use of certain
> browser features by using not-quite-standard constructs
> - the popularity of bells-and-whistles plug-ins (java, flash, etc.)
> to
> empower webpage "content delivery" and their associated advertisements
> - the size of the webpage development market, and the consequent
> number of webpage mechanics, 20% of whom are of better than average
> competence.
> In so many words, if your mechanic's concept of a validity test is
> that
> it works with the version of IE and Java and Flash on his system, you
> can expect a low level of compliance.
>
> I have no doubt that if and when we start seeing significant numbers
> of
> RDF and OWL ontologies, or even document annotations, on the Web, we
> will start seeing significant numbers of _invalid_ RDF and OWL
> documents. But in that community, because of its size and nature
> (small
> market, high competence), much more attention will be paid to "doing
> the
> thing right". I would bet that 80% of current and future RDF and OWL
> documents will be valid. Some that are technically invalid will be
> accepted by parsers anyway, and probably interpreted as intended;
> others
> will be rejected by the parsers and never participate in any reasoning
> activity. (02)
Um... I wonder why everyone on this forum uses the future tense when
referring to the semantic web. Right now, as we type, there are
millions of RDF and OWL documents published on the Web. It is quite
hard to make RDF invalid, but a large fraction of the declared OWL-DL
ontologies are not in fact strictly valid OWL-DL. Already there are
routinely used software tools which auto-correct the most common
validity errors (missing object property and class declarations) and,
indeed, the results almost always interpret as intended. The newer
specs for OWL-2 will be more permissive in any case. So, yes, what you
say is right, but its not a prediction, it has already happened. The
OWL specs are among the most complicated and baroque spec documents
ever written, and yet the sky has not fallen. (03)
> But that is not the comparison John was making. What will make or
> break
> automated reasoning over multiple information sources is, to
> paraphrase
> John's point, how many of the valid ontologies "do the right thing".
> How many of them convey 'correct' or at least 'consistent'
> information?
> The Web in general is the source of as much misinformation as useful
> information, and we have no reason to suppose that "ontology-
> engineered"
> information will be any more correct. (04)
I disagree. Its easy for any Joe Plumber to blog on the Web, and easy
to write nonsense into a Wiki. But to blather in RDF or OWL takes more
skill, and that skill barrier means that one would have to be
genuinely malicious or slightly insane to do it. And what gain would
accrue? (05)
> Further, my experience as a
> modeler tells me that most people generalize incorrectly quite often.
> We are perforce all guilty of false induction from time to time, based
> on limited knowledge and experience, and our ontologies will reflect
> that. (This is just yet another phrasing of Pat Hayes's "Horatio
> principle".)
>
> The big issue for the proponents of "ontology repositories" is not
> whether the proffered ontologies are valid OWL/RDF/CLIF. It is: How
> do
> you decide whether a proffered ontology is "good"? (06)
You have to trust the source, the publisher. I agree that we have no
way to compute such trust at the present, but Im sure it will evolve.
Its not hard to imagine several working scenarios, eg a SWeb 'good
housekeeping seal' applied at use time by an agency paid a micro-fee
by the owners of the branded ontologies. (07)
> And how do you
> resolve discrepancies when trying to enrich your overall knowledge
> base?
> Is the new information wrong? or the old information? (08)
There is a lot of current discussion about ways of 'versioning'
ontologies for just this reason. (09)
> Or does the new
> ontology just reflect a viewpoint for which the reconciliation with
> other viewpoints is not yet fully developed in the community? (All of
> these issues came up in the last summit.) (010)
Yup, and bioinformatics is very concerned with such issues, and is the
community most likely to create standards or at least methods that
might lead to standards for handling such questions. Again, all this
is active work, being done right now by people for whom the results
matter. It is no longer armchair theorizing. If y'all want to have
something to say, get involved with the actual work, would be my
advice :-) (011)
Pat (012)
>
>
> -Ed
>
>
> --
> Edward J. Barkmeyer Email: edbark@xxxxxxxx
> National Institute of Standards & Technology
> Manufacturing Systems Integration Division
> 100 Bureau Drive, Stop 8263 Tel: +1 301-975-3528
> Gaithersburg, MD 20899-8263 FAX: +1 301-975-4694
>
> "The opinions expressed above do not reflect consensus of NIST,
> and have not been reviewed by any Government authority."
>
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