Carathéodory’s theorem in convex geometry

E118706

Carathéodory’s theorem in convex geometry is a fundamental result stating that any point in the convex hull of a set in ℝⁿ can be expressed as a convex combination of at most n+1 points from that set.

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Statements (45)

Predicate Object
instanceOf result in convex analysis
theorem in convex geometry
appliesTo points in the convex hull of a set
subsets of ℝⁿ
assumes standard Euclidean structure on ℝⁿ
assumption ambient space is finite-dimensional
bounds the number of points needed in a convex combination representing a convex-hull point
category theorem about convex hull representations
concept Carathéodory’s theorem in convex geometry self-linksurface differs
surface form: Carathéodory number
consequence convex hull of a set in ℝⁿ equals the set of convex combinations of at most n+1 points from the set
domain Euclidean space ℝⁿ
equivalentTo the statement that the Carathéodory number of ℝⁿ equals n+1
field convex analysis
convex geometry
discrete geometry
generalizationOf the fact that in ℝ² any point in a convex hull is a convex combination of at most 3 points
the fact that in ℝ³ any point in a convex hull is a convex combination of at most 4 points
guarantees existence of a representation of a convex-hull point using at most n+1 points
historicalPeriod early 20th century mathematics
holdsIn any real finite-dimensional normed vector space (via linear isomorphism with ℝⁿ)
implies every point in the convex hull of a finite set in ℝⁿ is a convex combination of at most n+1 of its points
inspired various colorful and fractional Helly-type theorems
involves affine independence
barycentric coordinates
mathematicalSubjectClassification 52A20
namedAfter Constantin Carathéodory
proofTechnique induction on the dimension n
use of affine dependence and Radon partitions
relatedTo Helly’s theorem
Krein–Milman theorem
Minkowski’s theorem on convex sets
Radon’s theorem
requires nonempty subset of ℝⁿ
point belonging to the convex hull of the subset
statement Any point in the convex hull of a subset of ℝⁿ can be written as a convex combination of at most n+1 points of that subset.
strengthenedBy Carathéodory’s theorem in convex geometry self-linksurface differs
surface form: colorful Carathéodory theorem
topic convex combination
convex hull
finite-dimensional vector spaces
typeOf finiteness theorem for convex hull representations
upperBound n+1 points in ℝⁿ
usedIn combinatorial geometry
computational geometry
linear programming theory
optimization

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Full triples — surface form annotated when it differs from this entity's canonical label.

Constantin Carathéodory notableWork Carathéodory’s theorem in convex geometry
Riemann mapping theorem relatedTo Carathéodory’s theorem in convex geometry
this entity surface form: Carathéodory theorem
Carathéodory’s theorem in convex geometry concept Carathéodory’s theorem in convex geometry self-linksurface differs
this entity surface form: Carathéodory number
Carathéodory’s theorem in convex geometry strengthenedBy Carathéodory’s theorem in convex geometry self-linksurface differs
this entity surface form: colorful Carathéodory theorem