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)j∈J.
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.
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Famous quotes containing the words index and/or set:
“Exile as a mode of genius no longer exists; in place of Joyce we have the fragments of work appearing in Index on Censorship.”
—Nadine Gordimer (b. 1923)
“Nothing in medieval dress distinguished the child from the adult. In the seventeenth century, however, the child, or at least the child of quality, whether noble or middle-class, ceased to be dressed like the grown-up. This is the essential point: henceforth he had an outfit reserved for his age group, which set him apart from the adults. These can be seen from the first glance at any of the numerous child portraits painted at the beginning of the seventeenth century.”
—Philippe Ariés (20th century)