All Questions
4 questions
37
votes
3
answers
3k
views
An entropy inequality
Let $X,Y$ be probability measures on $\{1,2,\dots,n\}$, and set $K=\sum_i\sqrt{X(i)Y(i)}$ so that $Z:=\frac{1}{K}\sqrt{XY}$ is also a probability measure on $\{1,2,\dots,n\}$. How can we prove the ...
16
votes
7
answers
6k
views
Understanding Gibbs's inequality
Short version
Gibbs's inequality is a simple inequality for real numbers, usually
understood information-theoretically. In the jargon, it states that
for two probability measures on a finite set, ...
2
votes
0
answers
118
views
Inequality for log-likelihood ratio
Let $ p, q $ be two probability densities on $ [0,1] $, strictly positive over $ (0,1) $. Let $ P $ be the cumulative function of $ p $, i.e., $ P(x) = \int_0^x p(x') \, \mathrm{d}x' $, $ x \in [0,1] $...
1
vote
2
answers
275
views
A corollary of Gibbs' inequality
Gibbs' inequality is equivalent to:
\begin{equation}
\sum_{i} \ln q_i^{p_i}-\ln p_i^{p_i} \leq 0
\end{equation}
where $p_i,q_i \in [0,1]$ and $\sum_i p_i = \sum_i q_i=1$.
Now, a friend of mine ...