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Sets are fundamental objects in mathematics. Intuitively, a set is merely a collection of elements or ''members''. There are various conventions for textually denoting sets. In any particular situation, an author typically chooses from among these conventions depending on which properties of the set are most relevant to the immediate context or on which perspective is most useful. == Denoting a set as an object == Where it is desirable to refer to a set as an indivisible entity, one typically denotes it by a single capital letter. In referring to an arbitrary, generic set, a typical notational choice is . When several sets are being discussed simultaneously, they are often denoted by the first few capitals: , , , and so forth. By convention, particular symbols are reserved for the most important sets of numbers: : – empty set (also or or are common) : – integers (from ''Zahl'', German for ''integer''). : – natural numbers : – rational numbers (from ''quotient'') : – real numbers : – complex numbers Some authors use the blackboard bold font for these particular sets (, , etc.). This usage is widely accepted in handwriting, but many mathematicians, and such experts on mathematical typography as Donald Knuth, advise against its use in print.〔Krantz, S., ''Handbook of Typography for the Mathematical Sciences'', Chapman & Hall/CRC, Boca Raton, Florida, 2001, p. 35.〕 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「set notation」の詳細全文を読む スポンサード リンク
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