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The Grelling–Nelson paradox is a semantic self-referential paradox concerning the applicability to itself of the word "''heterological''", meaning "inapplicable to itself." It was formulated in 1908 by Kurt Grelling and Leonard Nelson and sometimes mistakenly attributed to the German philosopher and mathematician Hermann Weyl.〔Weyl refers to it as a "well-known paradox" in ''Das Kontinuum'', mentioning it only to dismiss it. Its misattribution to him may stem from (attested in ).〕 It is thus occasionally called Weyl's paradox as well as Grelling's paradox. It is closely analogous to several other well-known paradoxes, in particular the barber paradox and Russell's paradox. ==The paradox== Suppose one interprets the adjectives "autological" and "heterological" as follows: # An adjective is ''autological'' (sometimes ''homological'') if and only if it describes itself. For example "noun" is autological, since the word "noun" is itself a noun. "English," "unhyphenated" and "pentasyllabic" are also autological. # An adjective is ''heterological'' if it does not describe itself. Hence "long" is a heterological word (because it is not a long word), as are "hyphenated" and "monosyllabic". All adjectives, it would seem, must be either autological or heterological, for each adjective either describes itself, or it doesn't. Problems arise in a number of instances, however: 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「Grelling–Nelson paradox」の詳細全文を読む スポンサード リンク
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