[XML-DEV Mailing List Archive Home] [By Thread] [By Date] [Recent Entries] [Reply To This Message] Re: Linkbases, Topic Maps, and RDF Knowledge Bases -- help me
Uche Ogbuji says - > > > - Create or use class hierarchies > > RDF: similar to hierarchies in constructs. > > TM: Same as for hierarchies. > > Both are really type hierarchies, and the class/type confusion is part of > the OO pollution. > One kind of hierarchy is the type-instance one, another is the class-subclass (or could be called type-subtype). The type-instance is natively supported in TM, but it is a great temptation to use it for type-subtype relationships anyway. You could declare class-subclass hierarchies in TM (no matter what you thought a class is supposed to be) but there is no native semantics for them. Both "type" and "class" have been used for a very long time in logic nad philosophy, and their meaning seems to drift around. Are they the same (outside of OO)? Hmm... > > - Declare that one thing is an instance of type. > > RDF: Very feasible > > TM: built-in, duck soup > > Why is this "very feasible" in RDF? It's built in as well: > Well taken, forgot about that one. > <rdf:Description > about="http://spam.com#Malatesta" > type="http://art.org#Patron"> > [...] > > > > TM: feasible but must be layered on top, primarily no doubt by defining > > the nature of various association topics. May become built-in in the > > future. > > Oh. I think I see what you mean now, but it's just another example of why > RDF is low-level. Inferencing itself can be built using RDF constructs in > a variety of ways. > How is this different in level, though, from TM, abut which the same xould be said? > Containers are one of the things that pollute RDF's low-level nature, and > I think this is part of why they are problematic. I think that containers > should be built at a level on top of RDF. > I'm not too sure about this. I mean, you can do any static logic circuit with NAND gates, but having other specialized types is very useful and may be better for performance. I don't mind specialized constructs if there aren't too many and they are well-designed to help to common jobs. > Perhaps RDF should be broken into 4 specs: > > 1) RDF Model (ditch the containers, aboutEachPrefix and all that other > sauce) > 2) RDF Library (useful collection of constructs built on (1), such as > containers and N-Ary relationships such as measured relationships and > general associations. > 3) RDF Schemas > 4) RDF Serialization (XML and LISP serializations for RDF) > Sounds good. > > - Filter. > > RDF: no particular built-in machinery. > > TM: built-in, elaborate machinery (scopes) > > Again, this is because RDF is lower level. You can build "scopes" on top > os RDF in many ways. One popular approach that has been discussed on > www-rdf-interest has been "contexts", which are similar to TM scopes. > Yup, each can be "extended" to supply things the other already has. Fun discussion! Cheers, Tom P
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