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   Fuzziness and Existence (was Re: RE: [xml-dev] Generality of HTTP)

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1/25/2002 4:46:15 PM, Mark Baker <distobj@acm.org> wrote:

>It only seems fuzzy because the principles behind it aren't well
>understood.  In actuality, it's anything but; it's the most powerful
>distributed software infrastructure that's ever been built.

I meant "fuzzy" in the fairly rigorous sense of fuzzy logic/set 
theory, see http://www.sciam.com/askexpert/computers/computers8.html
Definitely not in the perjorative sense of something that isn't 

From the SciAm page: "Fuzzy logic is a generalization of standard 
logic, in which a concept can possess a degree of truth anywhere 
between 0.0 and 1.0. Standard logic applies only to concepts that are 
completely true (having degree of truth 1.0) or completely false 
(having degree of truth 0.0). Fuzzy logic is supposed to be used for 
reasoning about inherently vague concepts, such as 'tallness.'" 

My point is simply that many things we discuss here such as "what the 
XML spec says" [c.f the discussion of what non-validating parsers are 
supposed to do with DTD information or the lack thereof], what "The 
Web" is, what the relationship between Push/Pull and event/tree 
processing models are, are "inherently vague concepts."  Maybe the 
XML spec could be formalized to the point where it is no longer 
intrinsically vague, but I doubt if we'll ever fully agree on the 
other stuff.  

I find "fuzziness" in this sense a very useful organizing concept: 
rather than debate what "The Web really is," propose criteria to 
define the "Webness" of a technology.  HTTP, HTML, and URIs probably 
have a 1.0 "degree of membership" in the fuzzy set "The Web" whereas 
UDP, FTP, PDF, etc. have a somewhat lower membership.  The "Webness" 
of XML is an interesting question ....

There are products (mostly designed in Japan) that take the "degree 
of truth" numbers and the math very seriously here and do powerful 
things; I would not even attempt to argue that we should do so here, 
I just find in a useful heuristic device for thinking about nasty "is 
X a Y" problems.  For example, in some sense it doesn't matter what 
the intent of the XML spec says: if all processors implement some XML 
feature in the same way, it is really and truly part of "XML."  If 
there is agreement in principle, but non-interoperability in 
practice, it has a high, but not complete degree of membership in 
"XML."  If the people here scratch their heads and can't agree on 
what the spec implies, and the processors do different things, it has 
a low but non-zero degree of membership in "XML."  

So, a practical person might use this heuristic and say "Hmmm, that 
feature has a non-unity degree of membership in XML, I think I'll 
stay away from it" rather than "Hmmm, the consensus of the gurus on 
xml-dev is that that feature is really and truly part of XML, so I'll 
use it." 



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