"calculus" and "formal system" From http://en.wikipedia.org/wiki/Propositional_calculus#Terminology a calculus is a formal system that consists of a set of syntactic expressions ...
Do abstractness and concreteness mean for formal systems and their models respectively? Do they relate to how big the theory is? For example, the theory of rings is richer than the theory of ...
First some definitions to make it clear what I'm talking about: A deductive system is a set $J$ of judgments together with a set $R$ of inference rules each of the form $$ j_0 \leftarrow j_1, ...