Re: Comprehensive understanding of logic languages

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Article #1539

#1539

From: Torkel Franzen
Date: Sat, 03 Oct 1992 18:47

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In article <1akmqnINNihd@coral.bucknell.edu> cwalker@canopus.bucknell.edu
 (carleton walker `93) writes:

   >A Horn clause is any rule, fact, or query.
   >Rules have the form A :- B1, B2, ... Bn.
   >Facts have the form A.
   >Queries have the form ?- A.

  "?- A"? What does this mean? Does it have something to do with
logic? Anyway, you left out the information needed for a truly
comprehensive understanding of logic languages. Horn clauses are so
named after Alfred Horn, who showed that theories axiomatizable using
Horn clauses are precisely those whose models are closed under
substructures and direct products. The significance of this fact is
immense, or at any rate not to be sneezed at.

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From: torkel@sics.se (Torkel Franzen)
Subject: Re: Comprehensive understanding of logic languages
In-Reply-To: cwalker@canopus.bucknell.edu's message of 3 Oct 1992 17:55:35 GMT
Message-ID: <TORKEL.92Oct3194748@bast.sics.se>
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Organization: Swedish Institute of Computer Science, Kista
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Date: Sat, 3 Oct 1992 18:47:48 GMT
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