  We consider the problem of rational uncertainty about unproven mathematical
statements, remarked on by G\"odel and others. Using Bayesian-inspired
arguments we build a normative model of fair bets under deductive uncertainty
which draws from both probability and the theory of algorithms. We comment on
connections to Zeilberger's notion of "semi-rigorous proofs", particularly that
inherent subjectivity would be present. We also discuss a financial view with
models of arbitrage where traders have limited computational resources.
