RE: what is a rule?

From: Wagner, G.R. (
Date: 03/04/03

  • Next message: Wagner, G.R.: "RE: what is a rule?"
    >> although we can come up with a formal account for a specific type 
    >> of rule, I think we should better not try to find a definitive formal 
    >> account for "rules", in general. 
    > Unless we do, it seems to me that the discussion is vacuous. 
    > We literally do not know what we are talking about. 
    Notice, you may define KIF, OWL, LBase (or whatever) rules,
    but you are not in a position to define "rules", in general.
    (Do they define "numbers", in general, or do they rather
    define natural, rational, etc. numbers?)
    >> At the problem domain level, rules are statements that express 
    >> (certain parts of) a business/domain policy (e.g., defining terms 
    >> of the domain language, defining or constraining domain operations) 
    >> in a declarative manner
    > Please say what is meant by 'declarative' here. 
    "Declarative", here, means not specìfying the details of how to 
    implement a policy but only specifying what constitutes the policy
    at the highest level of description (with preconditions and
    postconditions of implied actions).
    "If any 3 of the named analysts report a strong buy on the same  stock
    within the same day and before the market closes, then buy 1000 units  of
    that stock."
    >> At the (platform-independent) computational level, rules are formal  
    >> statements that operationalize domain policies and can be easily mapped 
    >> into executable statements of a programming platform.
    > That seems to cover any programming platform at all. 
    Not really, because you want to have a kind of direct support here.
    E.g., SQL systems directly support many important types of integrity
    constraints (by means of CHECK, CONSTRAINT and ASSERTION statements), 
    while C++ and Java do not.
    >> Rule languages used at this level are RuleML 0.82, SQL-99, OCL 2.0, ISO
    Prolog or KIF.
    > KIF is purely an assertional logic, and cannot be 'easily mapped' into 
    > executable statements. 
    So, KIF rules cannot be interpreted/executed by any inference engine?
    >> They may, for instance, specify reactions (e.g. for specifying the 
    >> reactive behavior of a system/agent in response to events) 
    > in what sense is a 'reaction' anything to do with reasoning?? 
    I normally reason before I react :-)

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