F-space
In
functional analysis, an
F-space is a
vector space V over the
real or
complex numbers together with a
metric d :
V ×
V →
R so that
- Scalar multiplication in V is continuous with respect to d and the standard metric on R or C.
- Addition in V is continuous with respect to d.
- The metric is translation-invariant, i.e. d(x+a, y+a) = d(x, y) for all x, y and a in V
- The metric space (V, d) is complete
Some authors call these spaces "Fréchet spaces", but in Wikipedia the term Fréchet space is reserved for
locally convex F-spaces.
Clearly, all Banach spaces and Fréchet spaces are F-spaces.
The Lp spacess for 0 < p < 1 are examples of F-spaces which are not Fréchet spaces.