Re: [xml-dev] Using the concepts of Category Theory to create betterXML

[Kurt Cagle <kurt.cagle@gmail.com>]

Roger,

<person:Joe> <person:favoritePerson> <person:John>.

<person:Elaine> <person:favoritePerson> <person:John>.

<person:John> <person:favoriteBreakfast> <breakfast:Eggs>.

<perons:Jane> <person:favoritePerson> <person:Elaine>.

<person:Elaine> <person:favoriteBreakfast> <breakfast:Cereal>.

<person:John> <person:favoritePerson> <person:Elaine>.

select ?firstPerson ?favoriteBreakfast where

{

?firstPerson <person:favoritePerson> ?favoritePerson.

?favoritePerson <person:favoriteBreakfast> ?favoriteBreakfast.

}

SPARQL expression is "a person's favorite person's favorite breakfast"

firstPerson  | favoriteBreakfast

Joe            | Eggs
Jane          | Cereal

John          | Cereal

Category theory looks to me just like a precursor to sparql. I'm working on a complex domain - the Federal health insurance exchange, and what becomes evident very quickly is that once you start dealing with multiple interconnected associational entity types, you leave the domain of XML hierarchies and find yourself firmly enmeshed in graphs.

Kurt Cagle
Invited Expert, XForms Working Group, W3C

Managing Editor, XMLToday.org

kurt.cagle@gmail.com

443-837-8725

On Fri, Aug 3, 2012 at 7:19 PM, Liam R E Quin <liam@w3.org> wrote:

On Fri, 2012-08-03 at 22:40 +0000, Costello, Roger L. wrote:
> Hi Folks,
>
> I am learning Category Theory [1] to enhance my data modeling skills and my functional programming skills.
>
> Despite just starting to learn the subject, I have already discovered some exciting things that I will be able to use in XML data modeling and in XSLT functional programming.
>
> Here's what I've learned:
>
> http://www.xfront.com/Using-the-Concepts-of-Category-Theory-to-Create-Better-XML-Data-Models.docx

This is close to an expression of what I think of as XML Normal Form:
informally,
(1) data is not duplicated, but is stored once and pointed to where
needed
(2) relationships are explicit
(3) similar items are stored together with a common ancestor -
hierarchy, if present beyond one level, is used only for grouping.

This is, I think, very different from Henry Thompson's use of the same,
or a similar, term, but closer to relational algebra's 3rd normal form.

However, the choice of how far down to go with "chunking" is subjective;
one could envision a Normal Form with no mixed content and all text
nodes at the same level, but the "followed by" relationship is common
enough in XML and so well supported in XML tools that it's much easier
to use the built-in followed-by than use explicit references.

Liam

--
Liam Quin - XML Activity Lead, W3C, http://www.w3.org/People/Quin/
Pictures from old books: http://fromoldbooks.org/
Ankh: irc.sorcery.net irc.gnome.org freenode/#xml

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