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Article #84Equivalence of Strong completeness and categoricity
From: Jean-Marc Alliot
Date: Wed, 22 Jul 1992 20:58
Date: Wed, 22 Jul 1992 20:58
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1441 bytes
This question is perhaps trivial but... I am first going to give the definition I am using, since many people use the same words for different things: Consistency: A system is consistent if, for any wff F, we can not have at the same time (F is a theorem) and (not F is a theorem). Categoricity: a system is categoric if, for any wff F, we have either (F is theorem) or (not F is a theorem). Strong completeness: a system based on a set S of axioms is strongly complete if for any wff F, we have either (F is a theorem) or (F added to S is an inconsistent system). Now the questions: 1) It seems quite clear that in any system which is a superset of propositional calculus Categoricity and Strong completeness are equivalent. However a short and clear demonstration would be very much welcome. 2) Does the property hold in the general case (I especially think of intuitionist logic) ? If the question is too trivial, a reference to a book giving the answers would be also welcome.
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Path: arc1-ca.pugleaf.net!sparky!uunet!mcsun!corton!cenaath.cena.dgac.fr!geant!alliot From: alliot@cenatls.cena.dgac.fr (Jean-Marc Alliot) Newsgroups: sci.logic Subject: Equivalence of Strong completeness and categoricity Message-ID: <1992Jul22.205827.16651@cenatls.cena.dgac.fr> Date: 22 Jul 92 20:58:27 GMT Sender: news@cenatls.cena.dgac.fr Organization: Centre d'Etudes de la Navigation Aerienne, Toulouse, France Lines: 30