Published online by Cambridge University Press: 12 March 2014
1. The purpose of the present paper is to formulate the problem of non-finitist proofs, and to solve it for certain extensions of the predicate calculus, and for analysis with the exclusion of the theory of sets of points. The corresponding problem for general formal systems is discussed in another publication [1].
To fix ideas we introduce the problem by examples from analysis. The general formulation is given in the text. Also, we shall use in the introduction the concepts decidable, verifiable, finitist without much formal explanation, because the reader is probably familiar with them, and they are defined early on in the text.
The paper presupposes some knowledge of the methods and results in the theory of proofs. These enable one to state the general problem rather more precisely.