Another look at namespaces

James Tauber jtauber at
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
Linguistics 101)

However, that point is misleading at best when applied to formal languages.
In particular:

* 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
you :-)

James Tauber / jtauber at /
Maintainer of :, and
<pipe>Ceci n'est pas une pipe</pipe>

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