In a formal mathematical system, the terms, expressions, propositions, and proofs of objects are all finite sequences of symbols that are constructed from a predefined countable number of variables, constants, predicates, and logical symbols according to rules specific to the system. Since the set of all these objects is therefore a countable set, it is possible to assign natural numbers to each object in a unique way that completely reflects its structure. Using this correspondence, it is possible to translate the meta-mathematical propositions of a formal system into propositions in natural number theory. Source: Heibonsha World Encyclopedia, 2nd Edition Information |
数学の形式的体系における対象の項,式,命題,証明は,いずれも,あらかじめ用意されている可算個の変数,いくつかの定数,述語,論理記号から体系固有の規則によって構成される記号の有限系列である。したがって,これらの対象の全体は可算集合であるから,おのおのの対象に一意のしかたで,しかもその構造を完全に反映するように,自然数を対応させることができる。この対応を用いて,形式的体系の超数学的命題を自然数論の命題として翻訳できる。
出典 株式会社平凡社世界大百科事典 第2版について 情報 |
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