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Re: [ontolog-forum] Proceedings: "Database & Ontology" mini-series Sessi

To: "[ontolog-forum]" <ontolog-forum@xxxxxxxxxxxxxxxx>
From: "John F. Sowa" <sowa@xxxxxxxxxxx>
Date: Sat, 14 Jul 2007 10:21:00 -0400
Message-id: <4698DBCC.9080108@xxxxxxxxxxx>
Paola,    (01)

In my previous note, I forgot to answer the following question:    (02)

PDM> My assumption, following your example 2 would be:
 > not only birds fly -  would I be right?    (03)

JFS> 2. Induction. Assume a general principle that subsumes many facts.
 >   Given: Tweety, Polly, and Hooty are birds. Fred is bat.
 >          Tweety, Polly, and Hooty fly. Fred flies.
 >   Assume: Every bird flies.    (04)


Yes, that is true.  But that is a separate observation.    (06)

The assumption made by induction is "Every bird flies."    (07)

The additional statement "Not only birds fly" follows
from two facts plus some background knowledge plus an
inference.  Following are the facts as given:    (08)

     Fred is a bat.  Fred flies.    (09)

The additional background knowledge, which was not stated
in the slide, is    (010)

     No bat is a bird.    (011)

 From that statement and the preceding facts, one can infer
by deduction:    (012)

     Some things fly that are not birds.    (013)

Then it is possible to rephrase that conclusion as a qualifier
to the preceding:    (014)

     Every bird flies, but not only birds fly.    (015)

In short, you could add that statement, but it is derived
by a more complex series of steps.  For teaching purposes,
it might be better to show that in a separate slide.    (016)

(And, of course, the statement "Every bird flies" has to be
qualified when you consider penguins and kiwis.  You also have
to exclude injured birds, baby birds, sleeping birds, and
dead birds -- remember the dead parrot from Monty Python.)    (017)

John    (018)

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