Reputation
1,857
Next privilege 2,000 Rep.
Edit questions and answers
Badges
2 26
Newest
 Revival
Impact
~19k people reached

Mar
31
accepted Example of $H^n(X,R)$ not equal to $Hom(H_n(X,R),R)$
Mar
31
comment Example of $H^n(X,R)$ not equal to $Hom(H_n(X,R),R)$
Yes, thanks! It's exactly what I wanted to know.
Mar
31
revised Example of $H^n(X,R)$ not equal to $Hom(H_n(X,R),R)$
edited body
Mar
31
comment Example of $H^n(X,R)$ not equal to $Hom(H_n(X,R),R)$
Thanks a lot for the answer. I had made a mistake in the question...could you please update?
Mar
31
revised Example of $H^n(X,R)$ not equal to $Hom(H_n(X,R),R)$
added 118 characters in body; edited title
Mar
30
asked Example of $H^n(X,R)$ not equal to $Hom(H_n(X,R),R)$
Mar
30
comment Finding joint probability from double marginals
note: cross-posted to MO mathoverflow.net/questions/201485/…
Mar
30
revised Finding joint probability from double marginals
edited tags
Mar
16
asked Disintegration of probability measures, reference request
Mar
16
comment Cross Product Intuition
Answer to 1: yes! That's why it only works in three dimensions, and in the general case you use the "exterior product" (look it up!).
Mar
16
asked Finding joint probability from double marginals
Mar
11
comment Maximum entropy distribution given second order marginals
In this case a constant 1/8 distribution is the max entropy solution...but I have no clue in the general case!
Mar
11
comment Maximum entropy distribution given second order marginals
Three binary variables $x,y,z$, take $p=1/4(\delta_{000}+\delta_{011}+\delta_{101}+\delta_{110})$. where $\delta_{xyz}$ is a peak at the position $xyz$. Visually, it is the 3D equivalent of "chess". It's easy to see that the double marginals are all constant.
Mar
11
comment Maximum entropy distribution given second order marginals
There always exist a distribution which has all the same double marginals, namely the original $p$. And possibly some other...among which we take the one with the highest entropy. If it were impossible to find others, it would mean that the double marginals determine $p$ uniquely, which is absurd.
Mar
11
comment Maximum entropy distribution given second order marginals
Why? Just take a lower entropy.
Mar
11
asked Maximum entropy distribution given second order marginals
Mar
2
comment What is the formula and the name of the mathematical-phenomenon seen at the ending of “Around the World in Eighty Days”?
Beat, as in wave physics?
Mar
1
comment What is the variance of self-information (or surprisal)?
Oh yeah sorry, thanks for the corrections.
Feb
27
asked What is the variance of self-information (or surprisal)?
Feb
21
answered preservation of the curvature tensor implies preservation of the connection?