Another look at namespaces
jtauber at jtauber.com
Sun Sep 19 04:19:06 BST 1999
Simon St.Laurent wrote:
> We seem to have fallen into linguistics.
And the problem with that is what exactly? :-)
Rick Jelliffe wrote:
> >> Again, Andrew is simply conflating schema and namespace. The idea that
> >> he and Tim are putting forward is that a language is defined by a
> >> set of content models; this confuses "language" with "grammar"
Paul Prescod wrote:
> >What definition of language are you using that does NOT state that every
> >language has one and only one grammar. Is there a book I can read that
> >defines it? The SGML Cookbook doesn't count.
Simon St.Laurent wrote:
> I could start with H.L. Mencken's _The American Language_ (Fourth Edition
> with Supplements, 1948), in particular a citation of Noah Webster, in
> (second supplement, p. 333)
Simon, you are talking about natural languages whereas Paul is talking about
formal languages. A formal language is a set of valid utterances. A (formal)
grammar is a collection of rules for generating that set of utterances.
Mind you, the notion of a formal grammar for a natural language is largely
due to Chomsky and you've already said you were never fond of him :-)
But that aside, XML is a formal language, not a natural one. Likewise, HTML
4.0 is (despite what anyone says) three separate (formal) languages. In the
case of HTML 4.0, the three share a common vocabulary, but they are separate
languages. <aside>Namespaces, by the REC's definition, are about
vocabularies, not languages.</aside>
> "They seem not to consider that grammar is formed on language, and not
language on grammar."
> That last sentence seems to summarize the problem we're having here.
Both "grammar" and "language" as they are used in this quote predate formal
notions by quite a few years! I think Noah Webster's point is merely that
linguistics should be descriptive, not perscriptive (first lesson in
However, that point is misleading at best when applied to formal languages.
* XML is a language defined by a grammar.
* The XML REC clearly says that a DTD is a grammar for a class of documents.
In a formal language view, this class of documents is a set of
utterances---a formal language.
> Whether or not _The SGML Cookbook_ makes this claim that a language is not
> constrained to a single grammar, I'll be making that claim in my next
Depending on what you mean by "not constrained to" and what type of
languages you mean, I either completely agree or completely disagree with
James Tauber / jtauber at jtauber.com / www.jtauber.com
Maintainer of : www.xmlinfo.com, www.xmlsoftware.com and www.schema.net
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