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Many-sorted logic can reflect formally our intention not to handle the universe as a homogeneous collection of objects, but to partition it in a way that is similar to types in typeful programming. Both functional and assertive "parts of speech" in the language of the logic reflect this typeful partitioning of the universe, even on the syntax level: substitution and argument passing can be done only accordingly, respecting the "sorts". There are more ways to formalize the intention mentioned above; a ''many-sorted logic'' is any package of information which fulfills it. In most cases, the following are given: * a set of sorts, ''S'' * an appropriate generalization of the notion of ''signature'' to be able to handle the additional information that comes with the sorts. The domain of discourse of any structure of that signature is then fragmented into disjoint subsets, one for every sort. ==Example== When reasoning about biological creatures, it is useful to distinguish two sorts: and . While a function makes sense, a similar function usually does not. Many-sorted logic allows one to have terms like , but to discard terms like as syntactically ill-formed. 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「Many-sorted logic」の詳細全文を読む スポンサード リンク
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