Preface, Workshop and conference on logic, algebra, and arithmetic: Tehran, October 18-22,2003, Foreword, Mathematical logic in Iran: A perspective, Real closed fields and IP-sensitivity, Categoricity and quantifier elimination for intuitionistic theories, Primes and irreducibles in truncation integer parts of real closed fields, On explicit definability in arithmetic, From bounded arithmetic to second order arithmetic via Automorphisms, Local-global principles and approximation theorems, Beatty sequences and the arithmetical hierarchy, Specker's theorem, cluster points, and computable quantum Functions, Additive polynomials and their role in the model theory of valued Field, Dense subfields of henselian fields, and integer parts, A recursive nonstandard model for open induction with GCD property and cofinal primes, Model theory of bounded arithmetic with applications to independence results, Ibn-Sina's anticipation of the formulas of Buridan and Barcan, Remarks on algebraic D-varieties and the model theory of differential fields, A simple positive Robinson theory with LSTP of STP, Categories of theories and interpretations.