Hahn-Banach extension theorem

Hahn-Banach extension theorem

[¦hän ¦bän·äkek′sten·chən ‚thir·əm]
(mathematics)
The theorem that every continuous linear functional defined on a subspace or linear manifold in a normed linear space X may be extended to a continuous linear functional defined on all of X.
References in periodicals archive ?
The Hahn-Banach extension theorem is without doubt one of the most important theorems in the whole theory of normed spaces.