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Re: [ontolog-forum] Thing and Class

From: Brian Stamper <stamper.10@osu.edu>
Date: Tue, 09 Sep 2008 16:19:37 -0400
To: "[ontolog-forum]" <ontolog-forum@ontolog.cim3.net>
Cc: SW-forum <semantic-web@w3.org>
Message-ID: <op.ug8dezqjaqobh5@ack584s5.lib.ohio-state.edu>

All,

As a rank newbie who is reading the SW forum trying to gain some  
understanding, I'm sorry to say I have to ask these questions.

1. Would it be correct to say, for the purpose of semantic-web@w3.org,  
that we are only interested in the definitions as expressed in:
http://www.w3.org/TR/rdf-mt/ and
http://www.w3.org/TR/owl-semantics/rdfs.html
Thanks to Jie Bao's post for that:
http://lists.w3.org/Archives/Public/semantic-web/2008Aug/0259.html

2. And if 1 is true, isn't this thread off-topic for the  
semantic-web@w3.org mailing list? Or are these definitions indeed still up  
in the air and this discussion pertinent to the Semantic Web? I thought  
this thread had left this forum for being OT.

Again, I ask this because I'm a newbie here to learn, and it is difficult  
to filter the topical from the off-topic when you are only beginning to  
understand this material. There is already too much information in the  
requisite, I'd rather not be burdened with irrelevant.

Thank you,
Brian Stamper


On Tue, 09 Sep 2008 15:34:08 -0400, John F. Sowa <sowa@bestweb.net> wrote:

> Michael,
>
> There is no law that says we have to agree on the words we use.
> But in order to communicate effectively and to avoid confusion,
> both among ourselves and among the people we're talking to, it
> is essential to use words in the same or approximately the same
> senses as well established usage.
>
>  > It only becomes an issue if we all have to agree on names, but
>  > that is unlikely to happen any time soon.
>
> If we are hoping to establish any kind of standards for ontology
> and related fields, we had better start by agreeing among ourselves.
> And it helps if we're consistent with common usage.
>
> Following is established usage in mathematics and logic:
>
>     The word 'set' is always defined by extension (i.e., two sets
>     with the same instances are the same; otherwise, different).
>
> Following is established usage, as attested by dictionaries such
> as the OED, Merriam-Webster, and any other you're likely to find:
>
>     The words 'category' and 'type' are defined by intension (i.e.,
>     common properties, qualities, or descriptions, independent of
>     the existence or nonexistence of any instances).
>
> The word 'class', however, is ambiguous because it has different
> definitions in various fields.  In mathematics and logic, it is
> often used as a synonym for 'set' or for a supertype of 'set'
> that includes collections that are too big to be a proper set.
>
> But the word 'class' also has ties to the verb 'classify', which
> is usually used for classification by common properties.  Therefore,
> the word 'class' is sometimes used as a synonym for 'type'.
>
> We had a debate about these issues on ontolog forum over a year ago,
> and the consensus that emerged is the following:
>
>   1. 'set' is consistently used in an extensional sense.
>
>   2. 'type' is consistently used in an intensional sense.
>
>   3. But 'class' is ambiguously used in either the meaning of 'set'
>      or the meaning of 'type'.  Therefore, any use of the word 'class'
>      is likely to create confusion, especially in a multidisciplinary
>      field, such as ontology.
>
> In short, if you want to be clear and precise, use the words 'set'
> and 'type'.  But if you use the word 'class', you're likely to create
> confusion.
>
> John
>
>
Received on Tuesday, 9 September 2008 21:10:56 GMT

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