[X-logic-www] XML

[Roger B. J. <rb...@rb...>]

In response to Neil Nelson DATE: 11/01/2000 09:07:45

I only just saw this, since the one thing I omitted to do when I set up
this list (it appears) is subscribe to it.
(which didn't stop me posting to it, I must fix that)

XML originated as a successor to HTML, but was quickly
seen to have broader application.
The role of XML as an alternative way of coding web pages
is now much less than its role in the exchange of structured data
on the web, but it is also used as a generic method of encoding
arbitrary languages.

For example XML is now used for MathML, i.e for mathematics.
It is also used for UML.

Any language whatsoever which has any connection with the web
is likely to come as or with an XML encoding.

In the above there are at least three major categories:

1. textual markup
============
As a successor to HTML and SGML.
XML used for this purpose is likely not to have a regular structure.
This has been the primary actual use of XML in X-Logic to date,
but this is not the primary intended role of XML in X-Logic.

2. structured data
============
This is probably the most popular usage at present on the web, 
and probably the one of greatest commercial significance in the
near to medium term.

In these applications an XML dtd or schema is used to describe
the constraints which ensure the regularity of the structured data.

This kind of usage will be important in X-Logic, but is not the
area in which X-Logic is expected to exell.

3. formal notations
=============
MathML is an example of this.
The concerns the use of XML vocabularies as a representation
for some language more expressive than is needed for transport
of data, but more regularly structured and more semantically
precise than natural languages or textual markup applications.

This is the primary area in which X-Logic has something to say,
but X-Logic provides a framework for combining computation
and reasoning over any XML dialect intended for category (2) or (3).
For languages in category (1) (natural languages) I would advocate
that these are handled by converters between (1) and (3) and that
deduction takes place in (2) and (3).

As far as data access is concerned, there are already XML query
languages defined and implemented (though no standard).
W3C has and XML query language as one of its future deliverables.
A logic query language for XML is one of the applications mentioned
at the X-Logic.org site, and this seems to me an important application
area (possibly commercially significant).

As far as X-Logic is concerned it is probably important to distinguish
between the use of XML in the "architecture" for the languages such
as formal logics which X-Logic is concerned with, and the use of
XML in building web sites.

As far as this list is concerned our primary interest is in the latter,
whereas the x-logic-arch list is the place for the former.
If we can get together a new generation web site then we can
use the comment/forum facilities on the site to hang a discussion
around the content of the web site and develop the story in that way.

Roger Jones
RB...@RB...