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In mathematics, the paratingent cone and contingent cone were introduced by Bouligand (1932), and are closely related to tangent cones.
Definition[]
Let be a nonempty subset of a real normed space .
Let some be given. An element is called a tangent to at , if there is a sequence of elements and a sequence of positive real numbers so that and
The set of all tangents to at is called the contingent cone (or the Bouligand tangent cone) to at .[1]
References[]
^Jahn, Johannes. Vector Optimization Theory, Applications, and Extensions, Second Edition, pp 90-91