and preliminaries -- A review of Gentzen's second consistency proof -- The intuitionistic system of number theory -- A formally intuitionistic system as strong as classical analysis -- Transfinite induction with respect to recursive wellorderings without function parameters -- A formally intuitonistic theory equivalent to classical transfinite induction with respect to recursive wellfounded trees with function parameters -- A system containing barinduction with respect to decidable predicates -- Harrop formulas -- The Markov principle -- Relative consistency proof of ZTN with respect to ZTi/IN*.