Comments on query algebra

• From: Martin Bryan <mtbryan@sgml.u-net.com>
• Date: Tue, 5 Dec 2000 11:28:20 -0000
• To: <www-xml-query-comments@w3.org>
• Message-ID: <017f01c05eb3$859ba1a0$bdc666c3@sgml>

Congratulations on producing the query algebra first draft. Its impressive.

The following questions occur to me on first reading:

Why do you use Bib0 rahther than Bib[0], which would be the XPath way of
identifying the first of a set of nodes? What happens if there is an element
name like H1 and H2? How do you identify that H10 is the first occurrence of
H1 and not the 11th of H?

In general, what is the mechanism for querying the contents of the second
subsection within the third section of the fourth chapter of the second part
of book located at URL XYZ?

What is the advantage of using empty in place of the more understandable
not?

In 2.15, where is AnyType used? (The text seems to confuse AnyType with
AnyTree.)

Why can't ContentType consist of a sequence of AttrGroup, ContentTypeVar?

When removing duplicates from forests is it clearly stated that it is the
first occurrence in the forest that is retained?

How will expressions based on the algebra be moved from server to server?

How can queries based on the algebra be used as extensions to URIs?

Martin Bryan

Received on Tuesday, 5 December 2000 07:03:16 UTC