| 释义 |
set A well-defined collection of objects. It may be possible to define a set by listing the elements: {a, e, i, o, u} is the set consisting of the vowels of the alphabet, {1, 2,…, 100} is the set of the first 100 positive integers. The meaning of {1, 2, 3,…} is also clear: it is the set of all positive integers. It may be possible to define a set as consisting of all elements, from some universal set, that satisfy some property. Thus the set of all real numbers that are greater than 1 can be written as either {x | x ε R and x>1} or {x : x ε R and x>1}, both of which are read as ‘the set of x such that x belongs to R and x is greater than 1'. The same set is sometimes written {x ε R | x>1}. See algebra of sets, russell's paradox, Zermelo-Fraenkel axioms.
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