TOPICS
Search

Milman's Theorem


Let X be a locally convex topological vector space and let K be a compact subset of X. In functional analysis, Milman's theorem is a result which says that if the closed convex hull co^_(K) of K is also compact, then K contains all the extreme points of co^_(K).

The importance of Milman's theorem is subtle but enormous. One well-known fact from functional analysis is that co^_(K)=co^_(E(K)) where E(K) denotes the set of extreme points of K. Ostensibly, however, one may have that co^_(K) has extreme points which are not in K. This behavior is considered a pathology, and Milman's theorem states that this pathology cannot exist whenever co^_(K) is compact (e.g., when K is a subset of a Fréchet space X).

Milman's theorem should not be confused with the Krein-Milman theorem which says that every nonempty compact convex set K in X necessarily satisfies the identity K=co^_(E(K)).


See also

Extreme Point, Extreme Set, Krein-Milman Theorem

This entry contributed by Christopher Stover

Explore with Wolfram|Alpha

References

Rudin, W. Functional Analysis. New York: McGraw-Hill, 1991.

Cite this as:

Stover, Christopher. "Milman's Theorem." From MathWorld--A Wolfram Web Resource, created by Eric W. Weisstein. https://mathworld.wolfram.com/MilmansTheorem.html

Subject classifications