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A topological vector space is a vector space $V$ over a topological field $\mathbb{K}$ (typically $\mathbb{K}=\mathbb{R}$ or $\mathbb{K}=\mathbb{C}$), together with a topology on $V$ such that vector addition and scalar multiplication are both continuous. Hilbert spaces and Banach spaces are examples of topological vector spaces.

8 votes

Closed vector subspaces of large powers of R

Yes, that's true. This is called a space of minimal type (see. H.H.Schaefer p.191): A locally convex space $X$ over $\mathbb R$ is isomorphic to some ${\mathbb R}^I$ ($I$ being a cardinal number) …
Sergei Akbarov's user avatar
3 votes
0 answers
114 views

Approximation of a linear functional by linear continuous functionals

Let $X$ be a locally convex space, $T$ a balanced convex compact set in $X$, and $f:X\to\mathbb{C}$ a linear functional which is (not necessarily continuous on $X$, but) continuous on $T$. It is not d …
Sergei Akbarov's user avatar
2 votes

Topological vector space textbook with enough applications

I would recommend you the book by Yu.I.Lyubich (an unfavourable Zentralblatt review is here, see comments below). It's a good introduction to functional analysis for people who are interested in appli …
4 votes
1 answer
289 views

When is a totally bounded set of an inductive limit contained in a component of this limit?

A. P. Robertson and W. Robertson in their "Topological Vector Spaces" VII, 1.4, (and H.Jarchow in "Locally convex spaces", 4.6, Theorem 2) prove the following proposition: Let $E=\lim_{n\to\infty} …
Sergei Akbarov's user avatar
5 votes
1 answer
209 views

Are linear continuous mappings open on totally bounded sets?

Let $X$ and $Y$ be locally convex spaces, and $\varphi: X\to Y$ a linear continuous mapping. Suppose first that $S$ is a compact set in $X$. Then $\varphi$, being considered as a mapping from $S$ to $ …
Sergei Akbarov's user avatar
3 votes
1 answer
156 views

$\varepsilon$-product in Bierstedt's paper

I am reading K.D.Bierstedt's paper Gewichtete Räume stetiger vektorwertiger Funktionen und das injektive Tensorprodukt. I. Journal für die reine und angewandte Mathematik 259 (1973): 186-210. It is wr …
Sergei Akbarov's user avatar
3 votes
1 answer
225 views

Is compact-open topology stable with respect to injective limits?

Let $X$ be a locally convex space, and $\{Y_i;\ i\in I\}$ a covariant system of locally convex spaces over a partially ordered set $I$, i.e. a system of linear continuous mappings is given $\sigma^j_i …
Sergei Akbarov's user avatar
4 votes
4 answers
745 views

On Köthe sequence spaces

I asked this a week ago at math.stackexchange, but without success. As far as I understand, there are several meanings of the notion of the Köthe sequence space, in particular, Hans Jarchow in his "L …
Sergei Akbarov's user avatar
5 votes
2 answers
270 views

Is a set of nuclear functionals equicontinuous in compact-open topology if it is equicontinu...

Let $H$ be a Hilbert space and $B(H)$ be its space of all (bounded) operators. A nuclear functional on $B(H)$ is a linear functional $f:B(H)\to{\mathbb C}$ that can be represented in the form $$ f(A)= …
Sergei Akbarov's user avatar
8 votes
1 answer
655 views

When does the dual to the space $K(X)$ of compact operators consist of nuclear functionals?

Let $X$ be a Banach space and $B(X)$ be its space of all (bounded) operators. A nuclear functional on $B(X)$ is a linear functional $u:B(X)\to{\mathbb C}$ that can be represented in the form $$ u(A)=\ …
Sergei Akbarov's user avatar
4 votes
0 answers
147 views

A characterization of nuclear functionals in terms of continuity with respect to some specia...

I think, nuclear functionals on the space of operators $B(X)$ (on a Banach space $X$) must have a characterization in terms of some special continuity. I would be grateful if somebody could help me wi …
Sergei Akbarov's user avatar
2 votes

Pontryagin-reflexivity of spaces of continuous functions

I would say that this is not well-known: It is well-known that a Banach space $V$ is always Pontryagin-reflexive, i.e. the natural map $V\to \text{Hom}_\mathbb{R}(\text{Hom}_\mathbb{R}(V, \mathbb{R}) …
Sergei Akbarov's user avatar