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Re: [ontolog-forum] Thing and Class

To: "[ontolog-forum]" <ontolog-forum@xxxxxxxxxxxxxxxx>
From: "John F. Sowa" <sowa@xxxxxxxxxxx>
Date: Sat, 06 Sep 2008 12:21:15 -0400
Message-id: <48C2ADFB.8010504@xxxxxxxxxxx>
This thread touches on many practical and philosophical issues, which
have important implications.    (01)

MB> An interesting ontological problem, otherwise known as the
 > "Family axe" i.e. this axe has been in our family for generations.
 > My father replaced the handle, his father replaced the head etc.    (02)

The US Army had a problem with identifying rifles.  They kept
track of the rifle assigned to each soldier, but not of the parts,
which could be replaced.  But what if a soldier requested parts
one at a time and reassembled them to form a duplicate rifle?    (03)

Their solution was to declare that one part could not be replaced.
That was the stock, which had a unique serial number.  If the stock
was broken, the soldier had to replace the entire rifle.    (04)

SB> In engineering practice (at least as described through ISO
 > 10303), a part is either an inseparable component or an assembly.
 > An assembly consists of sub-assemblies (which are assemblies)
 > and components. The definition of assembly is recursive.    (05)

Fifty years ago, almost all products were built as assemblies.
Anybody who had modest skills with a screwdriver and a set of
wrenches could take apart, reassemble, and repair cars, toasters,
and even radios.  But getting beyond replacing tubes in the radio
required some technical knowledge and skill with a soldering iron.    (06)

When individual transistors became integrated circuits, the
"field replaceable units", as IBM called them, kept getting
bigger and more expensive.  For their Quasar TV sets, Motorola
had the bright idea of designing components as pluggable units
that could be replaced as easily as vacuum tubes.  Unfortunately,
the most unreliable components turned out to be the plugs.
Furthermore, the cost of maintaining a vast inventory of such
units was prohibitive.  As a result, Quasar TVs were more
expensive and more unreliable than competing brands.    (07)

LO> The replacement and maintenance problem in the "equipment" area
 > is very like to the "replacement" and "maintenance" in the Personnel
 > area !  In the IFS ERP product they are under the common "object"
 > topic .  Suppose it will be good to have some common description
 > for them although of course it will be hard to describe a body as
 > an "assembling" .    (08)

For living organisms, there are no assemblies.  Every component
grows from a single egg that divides and subdivides into the
specialized cells of every organ from skin to bones to lungs to
the heart and brain.  A heart may be replaceable, but a successful
replacement requires adjacent cells to grow, subdivide, and bond
together.  As a result, the new heart becomes seamlessly integrated
with the other organs of the body.    (09)

RHM> Thus my concept hierarchy - my point of view - changes
 > with time, as the parts are assembled or disassembled.    (010)

That is one more reason why a strict tree is an inadequate
logical structure for representing an ontology.  Aristotle's
syllogisms supported multiple inheritance, and Leibniz took
the next step of systematizing the partial order into a lattice.    (011)

With a partial ordering (multiple inheritance) the type hierarchy
need not change, even though individual instances may be changing
constantly.    (012)

DN> Alignment with UML at a conceptual level is probably a great
 > goal given it allows the structure to also be expressed in UML.
 > If UML is not robust enough, custom stereotypes can easily be
 > built into a UML profile.    (013)

I strongly agree.  My major complaint about the Semantic Web is
that the designers ignored the most widely used official and
de facto standards and practices in comp. sci. and IT.    (014)

UML and relational DBs are two examples, but there are many others
that they ignored.  Now they complain that commercial enterprises
ignore their recommendations.  That shouldn't be a surprise.    (015)

John Sowa    (016)

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