We prove that if the linear-time and polynomial-time hierarchies coincide, then every model of Π1 + ¬Ω1has a proper end-extension to a model of Π1, and so Π1 + ¬Ω ⊢ BΣ1. Under an even stronger complexity-theoretic assumption which nevertheless seems hard to disprove using present-day methods, Π1 + ¬Exp ⊢ BΣ1. Both assumptions can be modified to versions which make it possible to replace Π1 by IΔ0as the base theory.We also show that any proof that IΔ0+ ¬Exp does not (...) prove a given finite fragment of BΣ1has to be “nonrelativizing”, in the sense that it will not work in the presence of an arbitrary oracle. (shrink)

This paper develops the very basic notions of analysis in a weak second-order theory of arithmetic BTFA whose provably total functions are the polynomial time computable functions. We formalize within BTFA the real number system and the notion of a continuous real function of a real variable. The theory BTFA is able to prove the intermediate value theorem, wherefore it follows that the system of real numbers is a real closed ordered field. In the last section of the paper, we (...) show how to interpret the theory BTFA in Robinson's theory of arithmetic Q. This fact entails that the elementary theory of the real closed ordered fields is interpretable in Q. (shrink)