Index set

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In mathematics, the elements of a set A may be indexed or labeled by means of a set J that is on that account called an index set. The indexing consists of a surjective function from J onto A and the indexed collection is typically called an (indexed) family, often written as (Aj)jJ.

In computational complexity theory and cryptography, an index set is a set for which there exists an algorithm I that can sample the set efficiently; i.e., on input 1n, I can efficiently select a poly(n)-bit long element from the set. [1]


The set of all the functions is an uncountable set indexed by .


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See also

de:Familie (Mathematik) it:Famiglia (matematica) hu:Halmazrendszer nl:Indexverzameling ja:添字記法 no:Familie (matematikk) zh:索引集