First-order theory of ⟨ℕ, 0, 1, +, <⟩ (no multiplication). Presburger (1929) proved it is decidable, complete, and admits quantifier elimination — a paradigmatic tame theory.
First-order theory of ⟨ℕ, 0, 1, +, <⟩ (no multiplication). Presburger (1929) proved it is decidable, complete, and admits quantifier elimination — a paradigmatic tame theory.