[sc34wg3] Re: Reducing redundant constructs

Patrick Durusau sc34wg3@isotopicmaps.org
Fri, 15 Jul 2005 07:15:50 -0400


Yes, set theory does say exactly what you have recited below.

The question is: What is the "set" in question.

If it is only the set of values, then yes, your reading is correct.

If the set in question is an identifier, plus a set of values, then the 
fact that sets of values are "identical" does not lead to the same 
result.  At least if the identifiers are different. If they are the 
same, then again, you are correct.

That may not get us any closer to agreement but it is now clear what I 
am contending?

Hope you are having a great day!


Lars Marius Garshol wrote:

>* Patrick Durusau
>| One of the issues where we did not follow the T+ model was on
>| "identical" subject proxies.
>Let me try to be a bit clearer on this.  In the editorial comments you
>say that
>  id({ < , 0 > }) = identifier
>(Using  instead of "bottom", since that doesn't exist on my keyboard,
>and they mean the same thing anyway.)
>Well, {< , 0, >} is a particular proxy, and any proxy that has a
>single property where the key is  and the value is 0 is the same
>proxy as that proxy, because they will be the same set. That's implied
>by the use of set theory, and if you don't like it you have to stop
>using set theory and find some formalism that does what you want.
>| On the whole the notion of "identical" outside of a definition of
>| "identical" just seems real problematic to me.
>Set theory has a definition of this, and you're bound by it, since
>proxies are defined to be sets.

Patrick Durusau
Chair, V1 - Text Processing: Office and Publishing Systems Interface
Co-Editor, ISO 13250, Topic Maps -- Reference Model
Member, Text Encoding Initiative Board of Directors, 2003-2005

Topic Maps: Human, not artificial, intelligence at work!