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Presburger arithmetic is the first-order theory of the natural numbers with addition, named in honor of Mojżesz Presburger, who introduced it in 1929. The signature of Presburger arithmetic contains only the addition operation and equality, omitting the multiplication operation entirely. The axioms include a schema of induction. Presburger arithmetic is much weaker than Peano arithmetic, which includes both addition and multiplication operations. Unlike Peano arithmetic, Presburger arithmetic is a decidable theory. This means it is possible to algorithmically determine, for any sentence in the language of Presburger arithmetic, whether that sentence is provable from the axioms of Presburger arithmetic. The asymptotic running-time computational complexity of this decision problem is doubly exponential, however, as shown by . ==Overview== The language of Presburger arithmetic contains constants 0 and 1 and a binary function +, interpreted as addition. In this language, the axioms of Presburger arithmetic are the universal closures of the following: # ¬(0 = ''x'' + 1) # ''x'' + 1 = ''y'' + 1 → ''x'' = ''y'' # ''x'' + 0 = ''x'' # ''x'' + (''y'' + 1) = (''x'' + ''y'') + 1 # Let ''P''(''x'') be a first-order formula in the language of Presburger arithmetic with a free variable ''x'' (and possibly other free variables). Then the following formula is an axiom: ::(''P''(0) ∧ ∀''x''(''P''(''x'') → ''P''(''x'' + 1))) → ∀''y'' ''P''(''y''). (5) is an axiom schema of induction, representing infinitely many axioms. Since the axioms in the schema in (5) cannot be replaced by any finite number of axioms, Presburger arithmetic is not finitely axiomatizable in first-order logic. Presburger arithmetic cannot formalize concepts such as divisibility or prime number. Generally, any number concept leading to multiplication cannot be defined in Presburger arithmetic, since that leads to incompleteness and undecidability. However, it can formulate individual instances of divisibility; for example, it proves "for all ''x'', there exists ''y'' : (''y'' + ''y'' = ''x'') ∨ (''y'' + ''y'' + 1 = ''x'')". This states that every number is either even or odd. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Presburger arithmetic」の詳細全文を読む スポンサード リンク
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