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thoughts on metadata

From: Michael Kifer <kifer@cs.sunysb.edu>
Date: Tue, 25 Mar 2008 02:26:12 -0400
To: public-rif-wg@w3.org (RIF WG)
Message-ID: <28025.1206426372@cs.sunysb.edu>



I think the current proposal for meta data is inadequate for the current
and future needs because it is not part of the syntax of the language, its
proposed is too limited, and in the current form it cannot be given a
semantics.

Here are some concrete problems.

1. Meta data can be attached to various parts of the rules, not just rules
   themselves, and this metadata can affect the semantics.
   A simple example is specifying that the output to a query must be sorted.
   This changes the semantics, since the answer is not a set any more
   but a list.

2. Some important types of rule systems are based on prioritized defaults
   (defeasible, courteous, preference LP).

      - Here metadata is part of the syntax and of semantics.
      - Typically metadata consists of rule labels and priority or
        preference information.
      - Metadata items are often *terms with variables* and not just strings.

3. The current proposal does not offer any obvious or natural way for the
   metadata to be processable by a (possibly different) rule set.

   


	--michael  
Received on Tuesday, 25 March 2008 06:26:46 GMT

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