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RE: Schemas As Anti-bodies and Dynamical Systems

• To: "'Bullard, Claude L \(Len\)'" <len.bullard@i...>,"'XML Developers List'" <xml-dev@l...>
• Subject: RE: Schemas As Anti-bodies and Dynamical Systems
• From: "Michael Kay" <mike@s...>
• Date: Thu, 10 Feb 2005 17:17:09 -0000
• In-reply-to: <15725CF6AFE2F34DB8A5B4770B7334EE07206BE6@h...>
• Thread-index: AcUPkI+roS5v3jT1RS2+LnE0786npgAAmopw

Most of this goes into my "incomprehensible to a mere computer scientist"
bucket, but the idea of an anti-schema is one I like. I wonder how many of
the restrictions in the capability of XML Schema disappear if we define the
constraints on a document using expressions such as satisfies(S1) and not
satisfies(S2)?

I expect someone will tell me there is a vast body of theory on forming the
union and intersection of regular grammars...?

Shame that in XSLT and XQuery, failing to validate against a schema is
always a fatal error.


Michael Kay 

> -----Original Message-----
> From: Bullard, Claude L (Len) [mailto:len.bullard@i...] 
> Sent: 10 February 2005 16:46
> To: XML Developers List
> Subject:  Schemas As Anti-bodies and Dynamical Systems
> 
> Two fun thoughts to ponder:
> 
> 1.  A common view of the schema or DTD is as a means 
> to validate the instance for acceptance.  However, 
> it is perfectly useful as a means to validate an 
> instance for rejection.  You can have anti-schemas, 
> anti-anti-schemas and so forth given some dynamic 
> exchange such as messages which are themselves, 
> evolving (the schema is a kind of message).
> 
> 2.  A URI as a namespace identifier takes a single 
> value from an infinite space and uses it to 
> label an instance from a potentially infinite 
> space (vocabularies are dynamic in time as 
> expressed by a schema signature).  If we think 
> of that variation as motion, then the equations 
> evolve in time.  If the DTD or schema for a 
> vocabulary is considered a classifier, then   
> as noted by Farmer and Packard, "in typical 
> studies in dynamical systems theory the dimension 
> and the components of the state vector are fixed. 
> In contrast while the list of variables in the 
> immune or classifier systems is always finite, 
> its composition varies with time.  As components 
> are created or destroyed the differential 
> equations describing the dynamics change 
> and both the dimension N and composition of 
> the state vector changes... Of course it is 
> possible to embed such a system in an infinite 
> dimensional space and view the dynamics as fixed 
> in time.  We find it more useful though to 
> construct an algorithm that generates the 
> appropriate dynamical equations in the lowest 
> possible dimensional state space and study the 
> dynamics in this context." (1)
> 
> (1) J.D. Farmer et al./The Immune System, Adaptation and 
> Machine Learning
> 
> len
> 
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  • Schemas As Anti-bodies and Dynamical Systems
    • From: "Bullard, Claude L (Len)" <len.bullard@i...>

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