Index set

From formulasearchengine
Revision as of 22:53, 30 December 2013 by en>APerson (Moved a phrase into parentheses in first sentence)
Jump to navigation Jump to search

Template:One source In mathematics, an index set is a set whose members label (or index) members of another set.[1] For instance, if the elements of a set A may be indexed or labeled by means of a set J, then J is 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.[2]

Examples

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

See also

References

  1. Template:Cite web
  2. {{#invoke:citation/CS1|citation |CitationClass=book }}