Skip to main content
Search type Search syntax
Tags [tag]
Exact "words here"
Author user:1234
user:me (yours)
Score score:3 (3+)
score:0 (none)
Answers answers:3 (3+)
answers:0 (none)
isaccepted:yes
hasaccepted:no
inquestion:1234
Views views:250
Code code:"if (foo != bar)"
Sections title:apples
body:"apples oranges"
URL url:"*.example.com"
Saves in:saves
Status closed:yes
duplicate:no
migrated:no
wiki:no
Types is:question
is:answer
Exclude -[tag]
-apples
For more details on advanced search visit our help page
Results tagged with
Search options not deleted user 11211

Banach spaces, function spaces, real functions, integral transforms, theory of distributions, measure theory.

8 votes

Applications of functional analysis beyond analysis(towards algebra, geometry, number theory...

Besides Hodge and index theories, mentioned in Qiaochu Yuan's comment above as applications of functional analysis to (complex) algebraic geometry and algebraic topology respectively, I believe that a …
2 votes
Accepted

Fourier transform of function on compact set and Sobolev norm equivalence

This seems to be one special case of the so called Fourier restriction problem (see, for instance, Terry Tao's discussion: http://terrytao.wordpress.com/2010/12/28/the-bourgain-guth-argument-for-provi …
Pedro Lauridsen Ribeiro's user avatar
1 vote
1 answer
316 views

Uniformly continuous functions and Borel hierarchy in the compact-open topology

Let $\Omega\subset\mathbb{R}^n$ be open, $\mathscr{C}(\Omega,\mathbb{R})$ the Fréchet space of real-valued continuous functions on $\Omega$ endowed with the compact-open topology, and $\mathscr{C}_u(\ …
Pedro Lauridsen Ribeiro's user avatar
4 votes

What properties should $C(M,\mathbb{R})$ have when $M$ is a $n$-dimensional manifold?

This is not really an answer but rather a long-ish comment. First of all, if $M$ is not compact, $\mathfrak{A}=C(M,\mathbb{R})$ is not really a C${}^*\!$-algebra but actually only a locally C${}^*\!$- …
Pedro Lauridsen Ribeiro's user avatar
7 votes
Accepted

For a tempered distribution $F$ on $\mathbb{R}^2$, what exactly does it mean by $\lvert F(x,...

I'll try to explain what Igor meant in his comments in a different way, maybe it helps. Of course, any tempered distribution is a distribution in the broader sense - more precisely, any compactly sup …
Pedro Lauridsen Ribeiro's user avatar
10 votes
Accepted

Is the space of tempered distribution second countable?

Since $\mathscr{S}'$ is the dual of an infinite-dimensional Fréchet space, the weak-* topology in $\mathscr{S}'$ is not even first countable. What people usually do is to define probability measures i …
Pedro Lauridsen Ribeiro's user avatar
14 votes
Accepted

Abstract result on partitions of unity?

I will leave to Yemon Choi discussing the answer from Gelfand-Raikov-Shilov's book (Commutative Normed Rings, I suppose?), and restrict myself to more recent discussions on the matter... There is an …
Pedro Lauridsen Ribeiro's user avatar
8 votes
2 answers
357 views

Can smoothness of curves into a convenient locally convex vector space be tested with just a...

Let $E$ be a (Hausdorff) locally convex vector space (from now on just "lcs" for short). We say that $E$ is convenient (also called locally complete, Mackey-complete or $c^\infty$-complete) if, given …
Pedro Lauridsen Ribeiro's user avatar
3 votes

Fourier Transforms restricted to mass shell

I doubt it. My reason is related to your comment: take your favorite function $f$ on $\mathscr{D}$, multiply it by a Gaussian with covariance $\sigma$ and centered around a point $x$ in the support of …
Pedro Lauridsen Ribeiro's user avatar
4 votes

Quantum fields and infinite tensor products

The "infinite tensor product" picture may be useful as a sort of concrete image of the state space of a quantum field theory, but in practice is rarely used because of the technical difficulties it br …
Pedro Lauridsen Ribeiro's user avatar
11 votes
4 answers
665 views

Is every non-negative test function the limit of a sequence of sums of squares of test funct...

Let $0\leq f\in\mathscr{D}(\mathbb{R}^n)$. As shown e.g. by J.-M. Bony, F. Broglia, F. Colombini and L. Pernazza, Nonnegative functions as squares or sums of squares, J. Funct. Anal. 232 (2006) 137-14 …
Pedro Lauridsen Ribeiro's user avatar
2 votes
1 answer
598 views

Stein's extension operator and wave front sets

Let $K\subset\mathbb{R}^d$ be a compact set with non-empty interior and Lipschitz boundary. In Section VI.3 of his book "Singular Integrals and Differentiability Properties of Functions", E. M. Stein …
Pedro Lauridsen Ribeiro's user avatar
5 votes
2 answers
667 views

Is every Montel locally convex vector space compactly generated?

Let $X$ be a Hausdorff locally convex vector space. Recall (my reference is the book of H. Jarchow, Locally Convex Spaces. B.G. Teubner, 1981) that we say that $X$ is a semi-Montel space if every boun …
Pedro Lauridsen Ribeiro's user avatar
8 votes

Separate continuity implies (joint) continuity

This is easy and comes from the fact that $V$, being a Fréchet space, is barrelled, that is, the locally convex topology of $V$ coincides with its strong topology $\beta(V,V')$ (where $V'$ = topologic …
Pedro Lauridsen Ribeiro's user avatar
2 votes

"Completeness" for weak convergence of unbounded closed operators on a separable Hilbert spa...

Not always. What you are talking about is also called "convergence in the sense of sesquilinear forms", because you are taking a pointwise limit in $D\times D$ of a sequence of sesquilinear forms $\al …
Pedro Lauridsen Ribeiro's user avatar

15 30 50 per page