Recursive logic frames

Abstract

We define the concept of a logic frame, which extends the concept of an abstract logic by adding the concept of a syntax and an axiom system. In a recursive logic frame the syntax and the set of axioms are recursively coded. A recursive logic frame is called recursively (countably) compact, if every recursive (respectively, countable) finitely consistent theory has a model. We show that for logic frames built from the cardinality quantifiers ''there exists at least lambda'' recursive compactness always implies countable compactness. On the other hand we show that a recursively compact extension need not be countably compact.