Analytic and Coanalytic Sets
Just beyond the Borel sets in complexity are the analytic sets and coanalytic sets. A subset of a Polish space X is analytic if it is the continuous image of a Borel subset of some other Polish space. Although any continuous preimage of a Borel set is Borel, not all analytic sets are Borel sets. A set is coanalytic if its complement is analytic.
Read more about this topic: Descriptive Set Theory
Famous quotes containing the words analytic and/or sets:
“You, that have not lived in thought but deed,
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But I, whose virtues are the definitions
Of the analytic mind, can neither close
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—William Butler Yeats (18651939)
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—John Ashbery (b. 1927)