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Re: Conceptual Graphs, N3, RDF, Semantic Web

From: Frank Manola <fmanola@mitre.org>
Date: Wed, 17 Jan 2001 17:45:22 -0500
Message-ID: <3A662082.3F3D48F2@mitre.org>
To: RDF Logic <www-rdf-logic@w3.org>
I believe the definition of "reification" intended in the context of RDF
is along the lines of McCarthy's, found at
http://www-formal.stanford.edu/jmc/generality/node6.html, to wit:

> Reasoning about knowledge, belief or goals requires extensions of the domain of objects reasoned about. For example, a program that does
> backward chaining on goals used them directly as sentences, e.g. on(Block1,Block2), i.e. the symbol on is used as a predicate constant of the
> language. However, a program that wants to say directly that on(Block1,Block2) should be postponed until on(Block2,Block3) has been achieved,
> needs a sentence like precedes(on(Block2,Block3),on(Block1,Block2)), and if this is to be a sentence of first-order logic, then the symbol on must
> be taken as a function symbol, and on(Block1,Block2) regarded as an object in the first order language. 
> This process of making objects out of sentences and other entities is called reification. It is necessary for expressive power but again leads to
> complications in reasoning. It is discussed in (McCarthy 1979). 

Whether RDF's reification accurately captures this intent is, of course,
another question.


Jon Awbrey wrote:
> No!  Quotation and reification are very different operations!
> 1.  Quotation is the treating of a sign (text, etc.) as an object
>     of discourse, which involves a potentially critical reflection
>     on the course of dis-course, and whether one accomplishes this
>     via quotation marks, phenomenological epoche, gödel numbering,
>     aesthetic distancing, or in some other way, is not really the
>     most important thing so long as one actually does achieve it.
>     It may be of interest to note that the nature of reflection and
>     the character of quotation are just special topics under the more
>     general heading of "propositional and intentional attitudes" (PAIA).
>     And it may be pertinent to note, especially in the CG Forum,
>     that a particular brand of answer to this question of PAIA
>     is deeply embedded in the syntactic style of all of Peirce's
>     Logical Graphs, independently of their interpretation in the
>     Entitative or the Existential modes.  To see how this is so,
>     notice that "denial" or "negation", better yet, Nand or Nnor,
>     comprise the logically simplest sorts of PAIA's.  For a very
>     interesting and relevant discussion of these points, see the
>     book that is affectionately known, by me anyway, as "RATLOT":
>     | Charles Sanders Peirce,
>     | 'Reasoning and the Logic of Things',
>     | 'The Cambridge Conferences Lectures of 1898',
>     | Edited by Kenneth Laine Ketner,
>     | With an Introduction by Kenneth Laine Ketner & Hilary Putnam,
>     | Harvard University Press, Cambridge, MA, 1992.
>     |
>     | AKA "Detached Ideas On Vitally Important Topics" (DIOVIT),
>     | 'Collected Papers of Charles Sanders Peirce', CP 1.616-677, ...
> 2.  So-called "reification", in view of the diverse ways that the word
>     has come to be (ab)used of late -- apparently by the sort of folks
>     who hear a buzz-word at a conference or a cocktail party and then
>     race right home to write up their own personal definition of it,
>     which they promptly trot out before their impressionable class
>     of undergraduates the very next morning, thus converting what
>     would otherwise have been an isolated bit of chaos, the mere
>     fancy of single tipsy evening, into a general pandemonium --
>     is now a very ambiguous term, having at least three distinct,
>     but very deceptively intermingled, meanings that I can detect:

Frank Manola                   The MITRE Corporation
202 Burlington Road, MS A345   Bedford, MA 01730-1420
mailto:fmanola@mitre.org       voice: 781-271-8147   FAX: 781-271-8752
Received on Wednesday, 17 January 2001 17:37:01 UTC

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