Linked Questions

8 votes
1 answer
1k views

What's the point of a point-free locale?

In [1, example C.1.2.8], a locale $Y$ (dense in another locale $X$) without any point is given. I fail to understand the point of such point-less locale - Why can't we identify those as the trivial ...
Student's user avatar
  • 5,230
4 votes
3 answers
800 views

Quick derivation of classical probability theory from von Neumann algebraic framework

Watching (the begining of) a lecture on free probability theory by Dimitri Shlyakhtenko https://www.youtube.com/watch?v=F8Urtr39jM0, I'm led to consider the following question Question. How can one ...
dohmatob's user avatar
  • 6,853
7 votes
2 answers
1k views

Conditional Expectation for $\sigma$-finite measures

Someone knows of some definition or reference of how to define conditional expectation for a measure space with $\sigma$-finite measure. I think it should be as follows: Let $(X,\mathcal{B},\nu)$ ...
Rusbert's user avatar
  • 193
6 votes
2 answers
1k views

Commutative von Neumann algebras and localizable measure spaces

This is not my subject so I apologize if my question is too obvious or understood from other pages. I read some pages such as Reference for the Gelfand-Neumark theorem for commutative von Neumann ...
Ilan Barnea's user avatar
  • 1,344
21 votes
1 answer
1k views

Which complete Boolean algebras arise as the algebras of projections of commutative von Neumann algebras?

Projections in an arbitrary commutative von Neumann algebra form a complete Boolean algebra. Moreover, a morphism of commutative von Neumann algebras induces a continuous morphism of the corresponding ...
Dmitri Pavlov's user avatar
20 votes
1 answer
686 views

A nice subcategory of the category of measurable spaces

Is there some notion of "nice" measurable spaces and "nice" maps between them which satisfies the following properties? The real line equipped with the Lebesgue $\sigma$-algebra is nice. Any ...
Taylor Friesen's user avatar
5 votes
1 answer
358 views

Is there a meaningful interpretation of an $L^i$-space?

Do complex-normed spaces exist? Is there an extension of $p$-norms to $p\in\Bbb C\setminus\Bbb R$? A while ago I thought of extending $L^p$-spaces to the complex-normed setting. After some discussions,...
TheSimpliFire's user avatar
7 votes
1 answer
430 views

Is the Pierce spectrum useful elsewhere in Mathematics?

In Borceaux and Janelidze's Galois Theories, a construction of the Pierce spectrum is given. It is the poset of ideals in a Boolean ring. It's construction is reminiscent of the Zariski spectrum in ...
Mozibur Ullah's user avatar
4 votes
1 answer
609 views

Notation: Categories of measur(abl)e spaces

Is there a common notation in the literature for the category of measurable spaces and measurable maps? the category of measure spaces and measure-preserving maps? The nlab suggests $\mathsf{Measble}...
Martin Brandenburg's user avatar
11 votes
1 answer
483 views

Terminology for this notion of "$\sigma$-algebra" in a topos

Let $\mathcal{E}$ be a Grothendieck topos. I want to define a sort of "$\sigma$-algebra" for it, and I'm asking about what it should be—or already is—called. I know from nlab that Cheng spaces are an ...
David Spivak's user avatar
  • 8,659
4 votes
1 answer
309 views

Categorified probability and statistics?

To put it simply, what if the sample space underlying our probability space is a category instead of a mere set. Has a theory or probability and statistics been developed for such a situations in ...
Reza Rezazadegan's user avatar
2 votes
0 answers
468 views

A Grothendieck style reference for probability theory

This is a very vague question. I am looking for an "EGA" type of reference for probability theory. This means (among other things) that I'm looking for a text which develops the theory "abstractly".
QuestionMark's user avatar
5 votes
1 answer
217 views

Dense subcategory of measurable spaces

Recall the notion of a dense subcategory $\mathcal{D}$ of a category $\mathcal{C}$. It means that the restricted Yoneda functor $\mathcal{C} \to \mathrm{Hom}(\mathcal{D}^{op},\mathbf{Set})$, $A \...
Martin Brandenburg's user avatar
4 votes
1 answer
226 views

Definition of Radon measure on Takesaki's first volume

Consider the following theorem from Takesaki's first volume "Theory of operator algebras": In $(i)$, it is claimed that $L^\infty(\Gamma,\mu)$ is an abelian von Neumann algebra. How does ...
Andromeda's user avatar
  • 175
3 votes
1 answer
145 views

Reference for "the algebra of multiplication by all measurable bounded functions acts in Hilbert space in a unique manner"

I read a paper of Alain Connes on "Duality between shapes and spectra" and in page 4, he says Due to a theorem of von Neumann the algebra of multiplication by all measurable bounded ...
dohmatob's user avatar
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