From: "Richard H. McCullough" To: "RDF-Interest" Cc: "Richard S. Latimer" , "William Thomas" Subject: a hierarchy is an unambiguous lattice Date: Sun, 24 Nov 2002 19:26:44 -0800 Organization: retired from Bell Labs MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_000D_01C293EF.6C654C40" X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook Express 6.00.2800.1106 X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2800.1106 This is a multi-part message in MIME format. ------=_NextPart_000_000D_01C293EF.6C654C40 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Words are ambiguous because the same word is used in different contexts = with different meanings. We can pin down the meaning of a word, in a = given context, by using a genus-differentia definition. When we do that = we can arrange our words into a genus-species hierarchy (often called a = taxonomy). If we merge two different contexts together, using the same = word even though it has different meanings, we get a lattice (often = called an ontology). I very deliberately used the word "ontology". It is a sad fact that = many brilliant researchers in the field of Artificial Intelligence have = used ontologies instead of taxonomies. This AI research is the = foundation of the current Semantic Web activity. Enough abstractions. Let me give you a very simple example. Aristotle said: man is a rational animal. Ms. Feminist said: You chauvinist pig! Women are people too. Dr. AI said: OK, let's collect everything we know about "man". From Aristotle, we know that: man is an animal man is rational man has sex =3D male or female From Ms. Feminist, we know that person is an animal woman is a person with sex =3D female man is a person with sex =3D male woman is better than man Now that we have all this information together, we can see that the genus of man is animal and person man is rational man has sex =3D male or female Now I don't believe that any AI researcher is that naive. But I do = believe that many AI researchers have used ambiguous "definitions" of = words in less obvious cases, while simultaneously proclaiming that it is = "impossible" to define words. That is why genus-differentia definitions are part of the KR language. =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=20 Dick McCullough=20 knowledge :=3D man do identify od existent done knowledge haspart list of proposition ------=_NextPart_000_000D_01C293EF.6C654C40 Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable
Words are ambiguous because the same = word is used=20 in different contexts with different meanings.  We can pin down the = meaning=20 of a word, in a given context, by using a genus-differentia = definition. =20 When we do that we can arrange our words into a genus-species = hierarchy=20 (often called a taxonomy).  If we merge two different contexts = together, using the same word even though it has different meanings, we = get a=20 lattice (often called an ontology).
 
I very deliberately used the word = "ontology". =20 It is a sad fact that many brilliant researchers in the field of = Artificial=20 Intelligence have used ontologies instead of taxonomies.  This AI = research=20 is the foundation of the current Semantic Web activity.
 
Enough abstractions.  Let me give = you a very=20 simple example.
Aristotle said: man is a rational=20 animal.
Ms. Feminist said: You chauvinist pig! = Women are=20 people too.
Dr. AI said: OK, let's collect = everything we know=20 about "man".
From Aristotle, we know = that:
    man is an = animal
    man is = rational
    man has sex =3D male = or=20 female
From Ms. Feminist, we know = that
    person is an = animal
    woman is a person = with sex =3D=20 female
    man is a person with = sex =3D=20 male
    woman is better = than man
Now that we have all this information = together, we=20 can see that
    the genus of man is = animal and=20 person
    man is = rational
    man has sex =3D male = or=20 female
 
Now I don't believe that any AI = researcher is that=20 naive.  But I do believe that many AI researchers have used = ambiguous=20 "definitions" of words in less obvious cases, while simultaneously=20 proclaiming that it is "impossible" to define words.
 
That is why genus-differentia = definitions are part=20 of the KR language.
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D
Dick McCullough
knowledge :=3D man do = identify=20 od existent done
knowledge haspart list = of=20 proposition
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