Riesz representation for Hilbert functionals
Research context
postgraduate concept · established · As of 2026-10-10
Every continuous linear functional ell on a Hilbert space has a unique representing vector y with ell(x)=<x,y>, and ||ell||=||y||.
Key knowledge
Every continuous linear functional ell on a Hilbert space has a unique representing vector y with ell(x)=<x,y>, and ||ell||=||y||. This identifies the continuous dual with the Hilbert space, conjugate-linearly under the convention linear in the first argument. It is a different theorem from measure representation of positive functionals on continuous functions.
Values and equations
ell(x)=<x,y>; ||ell||=||y||
- ell
- Bounded linear functional
- x,y
- Hilbert-space vectors
Conditions and scope
- The functional is linear and bounded; the domain is complete in an inner-product norm.
- Changing which inner-product argument is linear changes the placement of conjugation.
Sources · 1
References
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Evidence and review
Author checked this English statement, displayed equation where present and stated hypotheses against these source locations: Lecture 17, minimizer theorem, orthogonal projection and Theorem 184. The check is bounded to the recorded claims; no complete proof reconstruction, software proof replay or universal literature completeness is claimed.
2026-10-10 · Author source-body/statement/equation/domain check, with graph associations scoped individually. Separate independent content/source/inventory review is required before branch closure.
Entry details
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