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== Definition ==
== Definition ==
A polyhedral cone {{math|cone(''Y'')}} is all linear combinations with nonnegative coefficients of a finite set of vectors {{mvar|Y}}.
Ziegler defines a polyhedral cone {{math|cone(''Y'')}} as the set of all linear combinations with nonnegative coefficients of a finite set of vectors {{mvar|Y}}.<ref>Ziegler, ''Lectures on Polytopes'' section 1.1</ref> In the case of the empty set, we define <math>\text{cone}(\emptyset) = \{\mathbf{0}\}</math>.


Equivalently, a polyhedral cone can be defined as the [[convex hull]] of the origin and a finite set of [[ray]]s extending from the origin.
Equivalently, a polyhedral cone can be defined as the [[convex hull]] of the origin and a finite set of [[ray]]s extending from the origin.

Grunbaum<ref>Grunbaum, Branko. ''Convex Polytopes'', page 9.</ref> generalizes this definition to allow an apex other than the origin, notated <math>\text{cone}_a\, Y</math> where {{mvar|a}} is the apex. Otherwise, the definition is the same.

== References ==
{{Reflist}}


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Latest revision as of 03:26, 2 September 2024

A polyhedral cone is a convex cone with a finite number of extreme rays.

Definition[edit | edit source]

Ziegler defines a polyhedral cone cone(Y) as the set of all linear combinations with nonnegative coefficients of a finite set of vectors Y .[1] In the case of the empty set, we define .

Equivalently, a polyhedral cone can be defined as the convex hull of the origin and a finite set of rays extending from the origin.

Grunbaum[2] generalizes this definition to allow an apex other than the origin, notated where a  is the apex. Otherwise, the definition is the same.

References[edit | edit source]

  1. Ziegler, Lectures on Polytopes section 1.1
  2. Grunbaum, Branko. Convex Polytopes, page 9.