Re: deductive databases

Jan Hidders <jan.hidders_at_REMOVETHIS.pandora.be> writes:

> Since we are doing PA they have to satisfy PA's axioms.

  You haven't specified that the structure contains + and * operations. Let's skip ahead a bit. Let L be the language of PA extended with two binary predicates p and q. By compactness, it is not the case that there is any set M of sentences in the language of L such that for every structure I obtained by adding to a model of PA two binary relations R and S interpreting p and q, I satisfies the sentences in M if and only if S is the transitive closure of R. Received on Sun May 22 2005 - 05:18:09 CDT