W3C home > Mailing lists > Public > www-rdf-logic@w3.org > May 2001

Re: What do the ontologists want

From: pat hayes <phayes@ai.uwf.edu>
Date: Fri, 18 May 2001 17:16:28 -0500
Message-Id: <v04210135b72b4db33933@[]>
To: "Sean B. Palmer" <sean@mysterylights.com>
Cc: www-rdf-logic@w3.org
>Isn't an "exclusive or" just stating something as being a disjoint

Not exactly; it is what is sometimes called the symmetric difference. 
That is, the class of things that satisfy (A xor B) is the things 
that satisfy B and not A, plus those that satisfy A and not B.  In a 
Venn diagram it looks like a figure-8 with a hole in the middle (in 
contrast with (A or B), which looks like the whole figure-8). 
Disjoint union looks like two circles that don't overlap.

For Booleans, the Venn diagram boils down to 4 points, so these 
distinctions get kind of blurred.

Pat Hayes

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Received on Friday, 18 May 2001 18:16:28 UTC

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