In the mathematical discipline of descriptive set theory, a '''coanalytic set''' is a set (typically a set of real numbers or more generally a subset of a Polish space) that is the complement of an analytic set (Kechris 1994:87). Coanalytic sets are also referred to as <math>\boldsymbol{\Pi}^1_1</math> sets (see projective hierarchy).
==References== {{refbegin}} * {{citation | authorlink=Alexander Kechris | author=Kechris, Alexander S. | title=Classical Descriptive Set Theory | publisher=Springer-Verlag | year=1994 | isbn=0-387-94374-9 | url-access=registration | url=https://archive.org/details/classicaldescrip0000kech }} {{refend}}
Category:Descriptive set theory
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