Preservation theorems for bounded formulas

In this paper we naturally define when a theory has bounded quantifier elimination, or is bounded model complete. We give several equivalent conditions for a theory to have each of these properties. These results provide simple proofs for some known results in the model theory of the bounded arithmetic theories like CPV and PV1. We use the mentioned results to obtain some independence results in the context of intuitionistic bounded arithmetic. We show that, if the intuitionistic theory of polynomial induction on strict Π2 formulas proves decidability of Σ b 1 formulas, then P = NP. We also prove that, if the mentioned intuitionistic theory proves LMIN(Σ1), then P = NP. 2000 Mathematics Subject Classification: 03F30, 03C10, 03F50, 68Q15.