In mathematical logic and descriptive set theory, the analytical hierarchy is an extension of the arithmetical hierarchy. The analytical hierarchy of formulas includes formulas in the language of second-order arithmetic, which can have quantifiers over both the set of natural numbers, and over functions from to . The analytical hierarchy of sets classifies sets by the formulas that can be used to define them; it is the lightface version of the projective hierarchy.
Read more about Analytical Hierarchy: The Analytical Hierarchy of Formulas, The Analytical Hierarchy of Sets of Natural Numbers, The Analytical Hierarchy On Subsets of Cantor and Baire Space, Extensions, Examples, Properties
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