Re: reifying variables

From: Drew McDermott (
Date: 02/11/04

  • Next message: Peter F. Patel-Schneider: "Re: reifying variables"
    Sandro has mentioned a couple of issues that come down to whether DRS
    is based on the assumption that a document encoding a formula in RDF
    using the DRS hack must be taken as a whole, with no guarantees that
    subtracting some arbitrary bunch of triples will leave a document
    whose meaning is entailed by that of the original document.
    More clearly: Let D be a set of triples obtained by using the DRS/SWRL
    translation mechanism to a logical formula F.  Let D' be an arbitrary
    subset of D, which happens to be the DRS/SWRL encoding of formula F'.
    Sandro points out that F may not entail F', which is contrary to the
    spirit of RDF.
    I have to plead guilty.  Making the triple be the fundamental unit of
    meaning in RDF was a bad idea, and no reasonable solution to the KR
    problem on the web can retain it.  The fundamental unit of "speech
    acts" in all other systems is defined by the syntax of a language.
    In most logics, the "speech acts" include assertion (always), plus
    querying, sequent posting, etc.  The syntax of the language determines
    what can be legally asserted, queried, etc.  To use DRS, you start
    with a language that defines these categories of well-formed formulas,
    you translate into RDF, and insist that if an agent is asserting a
    document representing a well-formed formula, then nothing can be said
    about whether it is asserting other well-formed formulae that might be
    extracted from the document.
                                                 -- Drew

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