Re: Nested Sets vs. Nested Intervals
Date: Wed, 9 Nov 2005 20:22:17 -0500
Message-ID: <16KdnTyyQOFbPe_eRVn-vw_at_comcast.com>
<amado.alves_at_netcabo.pt> wrote in message
news:1131576889.911246.121560_at_z14g2000cwz.googlegroups.com...
> Semantic domain is as you know the fancy name for the "things" you
> represent with your schema and data.
So what's the difference between a domain and a semantic domain ? If there is none, why muddy waters with the fancy names like "semantic" ?
>
> Relational *key* people (sorry, "star" was bad choice of word, unless I
> cited Kleene too:-) you know and cited two, Codd, Chen, and then
> there's Date, Ulman, Wiederhold, etc. and I would not mind citing here
> the people siting at the W3C working groups for XQuery, XPath, etc.
>
> E-R maps better to graph-based representations than to relational ones.
> It is not a matter of "can" but of "how well."
>
> No I won't mention UML nor say the dirty word ("semi-structured":-)
>
> There's lots of (good) graph-based models. RDF is (very) different from
> XML and both are (very) different from Codasyl and my baby called
> Mneson is (very, not so much, less) different from Codasyl, XML, RDF.
> (I suggest Mneson be discuss in the thread "Implementing a graph
> algebra" because that's it)
Could you pleas give a definition of the graph algebra ?
>
> The "network" model in particular, or Codasyl: nodes are tables with
> records and attributes. Not a pure graph. Actually not very graph-like
> at all. I think the technical term is "a dirty mess."
>
> How is RDF or XML different from Codasyl in particular: a lot
> different. An RDF node is a single concept, not a table like in
> Codasyl. An RDF edge is a single property out of a possibly (depending
> on the meta-schema) open set of properties, not the single relation
> "child" of Codasyl. Etc. RDF is a much cleaner model. A true graph
> model. This has good consequences at many levels (theory, practice,
> adoption). For example you can find very nice algebras for RDF out
> there.