Dear John, Matthew, Pat, Chris, David and Doug, (01)
John, that was very nicely put. It even
acknowledges that the supplier companies had their
own knowledge about how to advertise their
products to buyers within the Amazon database. (02)
But the Amazon solution is very much made up of
unstructured text, and the product search is
mostly using key words like Google uses for
search. So in that sense, Amazon's database
design is very basic, and its keyword search is
helpful but not new technology. It's a version of
SEO practices: using keywords to describe your
product the way your customers search for it. (03)
Is that your view of how future ontologies will be
used for interchange, i.e., a skeletal database
model with active users participating in the
database for their own purposes, and using
unstructured text to distinguish their products
from others? (04)
I can believe that description will be
successfully applied, as Amazon shows by example,
but how is that influenced by ontological
thinking? (05)
Inquisitively,
-Rich (06)
Sincerely,
Rich Cooper
EnglishLogicKernel.com
Rich AT EnglishLogicKernel DOT com
9 4 9 \ 5 2 5 - 5 7 1 2
-----Original Message-----
From: ontolog-forum-bounces@xxxxxxxxxxxxxxxx
[mailto:ontolog-forum-bounces@xxxxxxxxxxxxxxxx] On
Behalf Of John F. Sowa
Sent: Tuesday, March 13, 2012 9:46 AM
To: ontolog-forum@xxxxxxxxxxxxxxxx
Subject: Re: [ontolog-forum] Constructs,
primitives, terms (07)
Dear Matthew, Pat, Chris, David F, and Doug F, (08)
MW
> And if ontologies only guarantee something
partial, what is it that
> they DO guarantee? (09)
That is the critical question. Before we can
discuss it meaningfully,
we have to look at some systems that interoperate
successfully and
others that don't. Then we can ask how and why. (010)
> Logic does not have all the answers here. (011)
Logic is a tool. You can't solve any problem by
just looking at
the tools. You also have study the actual
problems themselves. (012)
PC
> The problem is that any necessary condition
added to a class creates a
> subclass, and both companies will know that they
cannot rely on accurate
> communication unless the subclass condition is
communicated to the other
> communicating system. Each system receiving
information can only rely on it
> being consistent with the logical specifications
communicated by the sending
> system. (013)
That is true. But the problem is more
complicated: (014)
1. Even if every term could be defined by
necessary and sufficient
conditions, you could still have specialized
uses in different
contexts. But most practical applications
have many terms that
cannot be defined by necessary and sufficient
conditions --
for example: employee, customer, business,
product, cost,
patient, disease, therapy, life, death... (015)
2. For any application that uses such terms,
it's unlikely that the
definitions in a general ontology G permit
exactly one model. But
an upper ontology is *intended* to support
multiple models. (016)
3. When you take a term defined in G, and use it
in a context that
adds more information (e.g., almost any
practical application),
any or all of the shared terms might be used
in a more specialized
sense -- for example, a subclass or subtype. (017)
4. If you have to add qualifiers to every term
that might be used
in any specialized sense in any application,
that defeats the
hope that shared vocabularies defined by
shared ontologies
with unique identifiers can, by themselves,
solve the problems. (018)
Now, let's consider a successful example of
interoperability among
thousands of businesses that use a shared
vocabulary with enough
shared structure to support applications: the
Amazon.com database. (019)
Amazon sells a huge number of products, and they
could never define
all of them precisely. So they don't even try.
They do have some
loosely defined product categories (books,
electronics, etc.) but they
let each supplier choose the category labels for
their own products. (020)
The suppliers can define their products in any way
they please. But
the only product description that Amazon requires
is a character string
that the Amazon DB stores for each product. But
the Amazon system just
moves that string it around, formats it, and
indexes the words in it. (021)
The reason why this method works is that Amazon
forces any supplier
that wants to sell their products to conform to
the Amazon conventions
and database schema. The sellers have to map
their data to the Amazon
categories and abide by Amazon conventions. But
the suppliers have
total control over how they design or describe
their own products. (022)
That's an example that works. Now let's consider
an example that
might use the Amazon ontology in a slightly
different way. (023)
Suppose that two suppliers A and B have mapped
their DBs to the
Amazon schema, and they have both been selling
their products
successfully. But if A and B find a need to share
some data among
themselves, they might consider adapting the
shared Amazon schema
for that purpose. Some potential pitfalls: (024)
1. The terms A and B share with Amazon about
products and categories
of products are almost completely undefined. (025)
2. Since Amazon just uses those terms for
classifying and indexing
what they sell, the customers who read the
product descriptions
use their own language skills to make
decisions. If they notice
a minor inconsistency in the classification,
they use a different
search term to find what they're looking for. (026)
3. But the details of the products are very
important for A and B.
Each company has its own system of
classification and its own
way of designing and describing products.
When A and B map
their internal categories to the Amazon
categories, the mappings
are almost always many to one. (027)
4. But the software and databases of A and B
can't adapt the way
people do. They can't read and interpret the
character strings
that Amazon presents to their customers. A
unique mapping between
the categories of A and B might be difficult
or impossible to find. (028)
The issues with the Amazon example plague any
shared general ontology.
It can only support interoperability for a limited
range of problems
for which it was designed. The ontology and the
URIs that go with it
might be a useful starting point for other
applications. But there
may be so many cross mappings that it could be
easier to start over. (029)
CM
> I suppose we can make something up, e.g.,
models M1 and M2 of theory
> G are inconsistent with each other if there is
some sentence A in
> the language of G (obviously not a theorem of
G) to which M1 and M2
> assign different truth values. (030)
Yes. I prefer to talk about the set of
ground-level facts in a database
as a model of the theory expressed by the
conjunction of all the DB
definitions and constraints (axioms). Whenever
you add a new axiom,
you reduce the set of permissible models (i.e.,
databases) that
that can satisfy that theory. (031)
CM
> it's the simple logical fact that every
consistent incomplete
> theory has consistent extensions that are
mutually inconsistent. (032)
Yes. The Amazon ontology is consistent and
incomplete. The thousands
of businesses that map to it have consistent
extensions that are
inconsistent with one another. It would be
counterproductive for
Amazon to design an ontology that has only one
model. (033)
CM
> it's not obvious that an interesting practical
ontology has to contain
> the arithmetic needed to guarantee
incompleteness and hence can't be
> complete. (034)
I doubt that any practical applications use
nonstandard models
of arithmetic. But everybody from Kant to
Wittgenstein noted that
you can't state necessary and sufficient
conditions for defining
any concepts that arise through common usage. (035)
You can take a common term, such as 'checking
account', and specify
some general definition that is sufficient for
electronic funds
transfer. That is similar to what Amazon does.
But the EFT definition
is *intended* to be sufficiently incomplete to
allow different models
for each bank that uses its own software for
checking accounts. (036)
David F
> To transmit a C' or C'' thing as a C thing is a
fair substitution;
> but to receive a C thing as a C' or C'' thing
does an implicit
> narrowing that is not necessarily valid. (037)
I agree. Anything defined in a specialized
ontology C' or C'' is
consistent with a general ontology C. But the
converse is not true:
an arbitrary thing defined in C might conflict
with the ways that C'
or C'' things are used. (038)
Doug F
> ... it appears that 'employee' is a class, not a
property. (039)
That is a distinction expressed in different ways
in different
notations. In any case, the issues about URIs and
interoperability
are independent of the notation and the metalevel
terminology. (040)
Doug F
> It is unlikely that either company has rules
that apply to all employees
> of all companies all over the world -- or even
in their local jurisdictions (041)
That's true, and it strengthens the points I was
trying to make. (042)
Doug F
> This suggests that a communication can be
incomplete if
> relevant parts of the context are not
transmitted as well. However,
> by defining contexts and rules within a context,
one has the option
> of verifying the constraints upon receipt of
information and/or
> transmitting the constraints with a query. (043)
I agree. But many people have been told that URIs
will solve their
problems. I just wanted to point out that the
problems require much
more analysis and more detailed conventions than
just using URIs. (044)
John (045)
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