[XML-DEV Mailing List Archive Home] [By Thread] [By Date] [Recent Entries] [Reply To This Message] RE: Soft Landing
In systems such as public safety, there are typically Master Indexes for: Names Locations Vehicles and these enable the network. The names data is particularly nasty to maintain and use. For example, given the name Robert Smith, how many of them do you think there are and how do you figure out which one is the one you are about to imprison for fifty years? The process of identification is very difficult, usually comes down to a guess by the operator, and in severe cases, comes down to a DNA test. That is why, BTW, a national DNA database is in the works and it is not to improve medical diagnosis. Then there is performance. Each one of these indexes is cross-referenced with different relationships. The problem of the semantic network approach is to reuse information and not build queries that have to search so far and so deep into child tables to create a report or fill a QBE form that one waits until the end of time. It is much harder than it looks. Semantic networks are constrained in utility by the top level domain classification. Ultimately, one ends up creating lots of semantic networks and they overlap. One problem is isolating the overlaps and indexing these to ensure that performance does not degrade. Harder than it looks. The overlap can also lead to pernicious or superstitious results. Expert systems don't scale well and that is one reason for not betting the web's future on them. When it gets down to defining what is "socially useful" you will find that there are many many definitions, cultural, political, financial and so on. It can quickly become a very bad brew of power, greed, and zealotry (power under religion). Caveat vendor. Len http://www.mp3.com/LenBullard Ekam sat.h, Vipraah bahudhaa vadanti. Daamyata. Datta. Dayadhvam.h -----Original Message----- From: David Megginson [mailto:david@m...] Sent: Friday, October 20, 2000 5:29 PM To: xml-dev@l... Subject: re: Soft Landing Dave Winer writes: > I wonder if anyone is interested in trying to set up a > mini-Semantic Web of content describing the people on this list, > what their interests are, what software they use, who else they > know, etc. My poor little mind needs to try something pragmatic to > figure out what all this stuff means. Dave Step one -- whether you're using RDF, Topic Maps, SOAP's serialization format, or XMI, is to decide what your classes are and what your properties are (note that I didn't say the classes and *their* properties). One of the classes is easy enough: - Person (or to include orgs, etc., Party) But what after that? Should we have an Interest class to represent shared interests, a WebSite class to represent Web sites, etc., or should we represent them simply as text strings? Here's the difference, first with just text strings (denormalized): <xd:Person rdf:about="http://megginson.com/ids/p001"> <xd:name>Dave Winer</xd:name> <xd:interest>XML</xd:interest> <xd:mailing-list>xml-dev</xd:mailing-list> </xd:Person> <xd:Person rdf:about="http://megginson.com/ids/p002"> <xd:name>David Megginson</xd:name> <xd:interest>XML</xd:interest> <xd:mailing-list>xml-dev</xd:mailing-list> </xd:Person> and then with more classes and objects (normalized): <xd:Person rdf:about="http://megginson.com/ids/p001"> <xd:name>Dave Winer</xd:name> <xd:interest rdf:resource="http://megginson.com/ids/i001"/> <xd:mailing-list rdf:resource="http://megginson.com/ids/m001"/> </xd:Person> <xd:Person rdf:about="http://megginson.com/ids/p002"> <xd:name>David Megginson</xd:name> <xd:interest rdf:resource="http://megginson.com/ids/i001"/> <xd:mailing-list rdf:resource="http://megginson.com/ids/m001"/> </xd:Person> <xd:Interest rdf:about="http://megginson.com/ids/i001"> <xd:name>XML</xd:name> </xd:Interest> <xd:MailingList rdf:about="http://megginson.com/ids/m001"> <xd:name>xml-dev</xd:name> </xd:MailingList> The second one is obviously more flexible, but at the cost of increased complexity -- in a real-world model, this would explode into hundreds or thousands of objects for only a few people and their interests. Anyway, this is an example of the kinds of decisions people need to make with or without a semantic web -- the design problem is where implementors spend most of their time and money, and RDF or XMI or Topic Maps or SOAP don't make that part any simpler. All the best, David -- David Megginson david@m... http://www.megginson.com/
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