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Re: names, URIs and ontologies

From: Lynn Andrea Stein <las@ai.mit.edu>
Date: Tue, 31 Oct 2000 14:08:38 -0500 (EST)
Message-Id: <200010311908.OAA09935@soggy-fibers.ai.mit.edu>
To: pat hayes <phayes@ai.uwf.edu>
Cc: Lynn Andrea Stein <las@ai.mit.edu>, www-rdf-logic@w3.org
Pat,

Let me spell out what I think I understand, then see whether it's my
understanding of logic, of URIs, or of your concerns that is broken.

LOGIC:

A logical name is an arbitrary symbol that takes its meaning from the
valid models of the theory (i.e., interpretations of that theory)
within which the name is used.

Two logical names spelled differently are different names.  They may
have the same interpretation (in some or all models), but they are
different names.  (In some logics, same-interpretation can be
constrained through the use of an equality/equivalence operator.)

A quantifier introduces a name whose spelling implicitly depends on
that quantifier.  E.g., in [forall x . foo (x)] and [forall x
. bar(x)], the x's are actually spelled differently because they're
scoped by two different quantifiers.

A logical name spelled the same way in two different occurrences
refers to the same thing (i.e., has only one interpretation that
covers both cases) provided both occurrences are within the scope of the same
quantifier(s).

URIs:

A URI is an arbitrary symbol that may be conventionally associated
with an operational process by which further
(non-logically-constraining) information or objects may be retrieved.
This process is (often) useful in establishing social conventions.
Note that a URI need not have such an associated process.

There are three kinds of URIs:

global URIs, which can be used anywhere and have the same associated
operational process (and, when we treat URIs as logical names, the
same intended interpretation) no matter where they are used.

local-only URIs, which can be used anywhere but are in effect
existentially quantified within the page of use (and for which any
associated operational process is relative to the page of use).

global-and-local URIs, i.e., local URIs with an explicitly spelled out
global prefix.  These have two-step operational processes (if any) but
logically behave like global URIs, i.e., they can appear anywhere and
have the same intended interpretation (and operational processes) no
matter where they appear.  To the extent that they are understood as
(existentially) quantified names, the quantifier is the global prefix,
NOT the page on which the URI appears.


Two URIs with the same spelling are the same name (and have the same
interpretation) iff the spelling includes a global part.  Two URIs
with different spelling are different names, though nothing prevents
them from having the same interpretation.


PAT's CONCERNS:

I think that Pat's worried that all URIs take meaning from the
containing name.  But only local-only URIs do this, so I don't think
it's an issue.

I also think Pat worries that someone needs to pick the One True
public name for Boston.  I think that this is the role of social
convention, that this usage evolves, and that there is already good
precedent for this happening with, e.g., RDF M&S.  I also think that
we can provide suggested conventions (which the market will or won't
adopt) and that we MUST provide some machinery by which two names
spelled differently can be identified as synonyms (e.g.,
daml:equivalentTo).  But again, this is analogous to the logical
situation.

I'm sure Pat has other concerns as well, but I'm not sure whether I
can do them justice here.  I started a longer response, but it seems
to me that this message spells out enough of the essential points that
I'll defer the other until I feel clearer about what's here.

                                             Lynn
Received on Tuesday, 31 October 2000 14:08:43 GMT

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