- From: Story Henry <henry.story@bblfish.net>
- Date: Mon, 6 Aug 2007 12:35:35 +0200
- To: <tim.glover@bt.com>
- Cc: <semantic-web@w3.org>
I am sure others here will have better answers that mine, but let me try... On 6 Aug 2007, at 11:43, <tim.glover@bt.com> wrote: > Henry wrote: > >>>>>> > > In logic programming you could always write something like > > Bachelor(x) :- Unamarried(x), Man(x) . > > But you knew that someone else could define those terms differently so > you could not merge the work from different groups easily, even if you > thought it was of the highest quality. The semantic web takes this > global naming seriously, and makes it clear how all these technologies > can work together, how they can be integrated. Neither UML, MOF, > nor SQL > nor prolog nor any of the other languages made this clear. > > <<<<< > > Well I agree that the major problem of data integration is the fact > that > people use the same words in subtly different ways. But can someone > please explain to me, how does putting http://xyz in front of all the > names help? URIs, are Universal Resource Identifiers. They act the way names and predicates are meant to work in mathematical logic. But URLs have the following extra features: - built into URLs is a notion of ownership. I own bblfish.net, so it is possible to assign responsibility, one way or another to statements. - It also allows distributed name creation. This is not easy when one uses mathematica logic. Did someone elese somewhere use the P1 predicate? How do I know. Ownership helps me decide this. If I coing names I own, I know I don't tread on other people's space. - these URLs can be dereferenced > "...someone else could define those terms differently..." > > If you mean by giving a different human interpretation of these words, > that is beyond the scope of the semantic web. If you mean by writing > alternative, inconsistent statements about bachelors and marriage, I > have heard repeatedly that that is perfectly acceptable, if not > positively encouraged! yes. For example I could name the bachelor concept with http:// bblfish.net/phil#Bachelor and you could do it at http://bt.com/~tglover/ont#Bachelor . This is what analytic philosophers do all the time when they try to distinguish different concepts, such as "knows". They will give a definition for say knows1, then knows2, etc... > > Is it because people who want to use a different definition can use a > different URI? But how do they KNOW that their definition is the > same or > different from someone else's? This is where it helps to have dereferenceable URLs. By doing a GET on a word we can find the core of its meaning. > The difference in meaning lies precisely > in the use people make of the words. It is more complex than that. People can use words as Putnam pointed out, without knowing their meaning. I may be able to say that "Gill has Multiple Sclerosis" correctly, even if I know very little of the meaning of the word. The meaning is given by the specialists in the field, and by reality. I can use the word wrongly, that won't make me right, as Alice correctly told Humpty Dumpty. Because dereferencing a URL makes it so easy to find a meaning, the owner of the URL, which can be a person or an institution, has a very large say on what it means. > What is to stop me and a colleague > across the planet from innocently and with the best of intentions > using > the URI in different ways, each believing that what we are doing is > correct in our own context? Nothing. People can and will use words wrongly. But where there is a right, there is a wrong. If we can dereference the URL, find the meaning, then that may help sort out the right from the wrong usage. Otherwise it may be that both of you are right. It would be interesting to come up with a real example here. > And having used different URIs, how do we > integrate that part of our knowledge we agree on? You can make statements such as <http://bt.com/~tglover/ont#Bachelor> = <http://bblfish.net/ phil#Bachelor> . or <http://bt.com/~tglover/ont#Bachelor> rdfs:subClassOf <http:// bblfish.net/phil#Bachelor> . or even perhaps with rules using SPARQL or N3 rules. > Perhaps the answer is something to do with dereferencing? yes. > Well it was recently pointed out on this thread that a dictionary > is a mechanism for > dereferencing ordinary names to content. But you seem to believe that > this does not solve the problem for ordinary words. The thing to notice here is that we are able to communicate. So insofar as you feel that the dictionary problem undermines real language, I would say it proves a limitation or misunderstanding of the dictionary argument. In essence signs always send one to further signs. Yet we do understand each other. Questions have to end somewhere: I would suggest that they end in action. The W3C has put together a core vocabulary (RDF, RDFS, OWL, etc...) which will be well understood by interpreters in the field. People are building reasoners on these vocabularies. Those reasoners will do transformations immediately on perceiving those words. They will not go and try further dereferencing. > Why is the web > logically different from a very partial dictionary, where most of the > entries are in Chinese? Complete knowledge is impossible. When you browse the web you learn a lot, even if you can never completely own all of the web. The semantic web will work in a similar way. Different software agents will be satisfied by understanding different subsets of the space. > Sorry to be so dense :( I think it requires a small aha! moment to get it. I suggest playing with N3, downloading cwm, writing your own foaf file, and then things get to make a lot more sense. :-) > Tim. > >
Received on Monday, 6 August 2007 10:36:00 UTC