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

1 vote
0 answers
53 views

Constrain representation of tempered distribution

This is a follow-up to this question. Let $T$ be a tempered distribution on $\mathbb{R}^d$. Then there is a multiindex $\alpha \in \mathbb{N}_0^d$, an $n \in \mathbb{N}_0$ and a bounded continuous fu …
iolo's user avatar
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3 votes
1 answer
126 views

Is a functional bounded by a measurable seminorm also measurable?

Let $\mu$ be a centred Radon Gaussian measure on a locally convex space $X$ and $q : X \to \mathbb{R}$ a seminorm that is $\mathcal{B}(X)_\mu$-measurable, where $\mathcal{B}(X)_\mu$ is the Lebesgue co …
iolo's user avatar
  • 651
7 votes
2 answers
1k views

Prove that a given distribution is tempered

Suppose I have a distribution $E$ such that $\phi \ast E$ is square-integrable for all $\phi \in C_c^\infty \left( \mathbb{R}^d \right)$. Is it possible to prove that $E$ is tempered? It seems plausib …
iolo's user avatar
  • 651
1 vote
1 answer
67 views

Local completion of bornological space

I recently stumbled across this old publication which defines the local completion of a Hausdorff locally convex space. The construction is as follows: A Hausdorff locally convex space $E$ is locally …
iolo's user avatar
  • 651
2 votes
Accepted

Local completion of bornological space

It turns out, that the above is actually rather simple. Clearly, $E$ is dense in $F$ with its subspace topology from $\widetilde{E}$. Furthermore, since $E$ is Mackey, it is well-known that its comple …
iolo's user avatar
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1 vote
Accepted

Is a functional bounded by a measurable seminorm also measurable?

I have found an answer exploiting the equivalence of Lusin and Borel measurability as stated in Radon Measures on Arbitrary Topological Spaces and Cylindrical Measures on page 6, theorem 5: Let $H : …
iolo's user avatar
  • 651
4 votes
1 answer
248 views

Understanding the Osterwalder-Schrader conditions as formulated by Glimm and Jaffe

$\newcommand{\real}{\mathrm{real}}$I am having trouble with understanding the axiom (OS3) in this book by Glimm and Jaffe. It defines \begin{equation} \mathcal{A} = \left \{ A(\phi) = \sum_{j = 1}^N c …
iolo's user avatar
  • 651
2 votes
Accepted

Understanding the Osterwalder-Schrader conditions as formulated by Glimm and Jaffe

Since this has confused me multiple times, I write this answer in the hope that it might help others. First, recall that reflection positivity as formulated by Osterwalder and Schrader states that \be …
iolo's user avatar
  • 651
2 votes
0 answers
243 views

Bochner integral in a Fréchet space

I have a Fréchet space $V$ whose topology is (if it helps) induced by a family $\mathcal{P}$ of norms - not just seminorms - and on this space I have a Borel probability measure $\nu$. Now, I would li …
iolo's user avatar
  • 651
1 vote
2 answers
192 views

When is a natural map between completions injective?

Let $X$ be a vector space equipped with a norm $p$ and a seminorm $q$. Denote the completion of $X$ with respect to $p$ with $X_p$ and with respect to $p+q$ by $X_{p+q}$. Then the induced map $\iota : …
iolo's user avatar
  • 651
2 votes
1 answer
154 views

Variation of concept of a Lusin space

Citing from Wikipedia, A Hausdorff topological space is a Lusin space if some stronger topology makes it into a Polish space. Is there a (previously studied) analogous concept of a Hausdorff (locall …
iolo's user avatar
  • 651
6 votes
1 answer
472 views

Fermions, their path integrals and effective actions

I just read the nice exposition Fermionic Path Integral on nLab and began to wonder about some details to which references appear to be lacking. Suppose we live on Euclidean space as in the Osterwalde …
iolo's user avatar
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0 votes
0 answers
22 views

Directions of differentiability of log-concave measures with infinite-dimensional support

I recently came across the very nice review "Differentiable Measures and the Malliavin Calculus" by Bogachev (1997) which begins by discussing measures $\mu$ on locally convex spaces $X$ with the prop …
iolo's user avatar
  • 651
2 votes
0 answers
178 views

Gauge invariance of a QFT path integral

If we consider the usual formal construction of a path integral over fields with gauge symmetries e.g as in Weinbergs "The Quantum Theory of Fields - Volume 2" the notion of gauge invariance is clear …
iolo's user avatar
  • 651
2 votes
0 answers
542 views

Euler-Lagrange equations on a differentiable manifold

I am following the conventions of https://arxiv.org/abs/math-ph/9902027 Let $M$ be a differentiable manifold, $E \to M$ a vector bundle over $M$ with fibre $F$, $J^1(E)$ the rank-one jet bundle over …
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