Tagged Questions

2
votes
1answer
190 views

A Johnson-Lindenstrauss lemma for finite fields?

Given $m$ points in $\mathbb{R}^N$, the Johnson-Lindenstrauss lemma guarantees the existence of a linear operator $\mathbb{R}^N\rightarrow\mathbb{R}^n$ that nearly preserves pairwi …
1
vote
1answer
235 views

how to prove a conjecture on a “canonical equivalent” of factoring

The following statement about finite differences of the positions of the ordered multiset of factors of $n$ in the sequence of primes seems to be true based on my empirical tests. …
1
vote
1answer
410 views

Stability in algebraic geometry

Suppose I have a collection of polynomials with multiple variables (more polynomials than variables, say), and I'm given noisy versions the values of these polynomials at a certain …
0
votes
1answer
61 views

order of convergence of the conditional entropy

Let $X_n$ be a random variable distributed on $A_n:=\{1, \ldots, n\}$ and $g_n\colon A_n \to A_n$ such that $\Pr\big(X_n \neq g_n(X_n)\big) \to 0$. Putting $Y_n=g(X_n)$ then by Fan …
6
votes
8answers
923 views

Existence of unknowable algorithms ?

Here by «algorithm» I mean a (halting) Turing machine with finite alphabet and memory. Is it possible to obtain by purely existential (i.e. non-constructive) means the existence …
0
votes
3answers
207 views

smallest number of comparisons needed

I have $n$ variables $b_1,\ldots,b_n$, each one $b_k\in {0,1}.$ Associated to each binary vector ${\bf b}=[b_1,\ldots,b_n]$ there are strictly positive function values $f({\bf b})$ …
0
votes
0answers
84 views

Behavior of a one-point-changing operation on functions

Let $n \in \mathbb N$, and $s: \mathbb N \rightarrow \mathbb N,\ p: (\mathbb N \rightarrow \mathbb N) \rightarrow \mathbb N$ be defined as follows: $$ s(x) = x + 1; \\ p(f) = c(1), …
1
vote
0answers
117 views

How to estimate the quantum fidelity between two given states

There is a well-known theorem, firstly obtained by Denes Petz, in quantum information theory, which is described as follows: $\mathbf{Theorem.}$ Let $\rho$ and $\sigma$ be two sta …
1
vote
1answer
165 views

Convexity and semicontinuity of the relative entropy function

There are several different definitions of relative entropy, and some of them are not equivalent. Following is the definition we will use in this question. Let $M$ be a closed man …
5
votes
0answers
81 views

Chernoff bound in the not-quite-sub-exponential case

In Terry Tao's notes on Concentration of measure, Exercise 7 indicates that the Chernoff bound can be generalized to sub-exponential random variables: http://terrytao.wordpress.co …
1
vote
2answers
454 views

A question about the size of a L1 ball

I met with a problem when I am reading a paper "On the Redundancy of Slepian-Wolf Coding" by He, DK; Lastras-Montano, LA; Yang, EH; Jagmohan, A; Chen, J, IEEE TRANSACTIONS ON INFOR …
2
votes
1answer
102 views

KL divergence(s) comparison,

Hi, $P_1$, $P_2$, $P_3$ are probability distributions defined on the same support. Knowing that $H(P_1) < H(P_2) < H(P_3)$, can we compare $D_{KL}(P_2,P_1)$ and $D_{KL}(P_3 …
9
votes
4answers
307 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 …
1
vote
1answer
135 views

Derivative of a random process

Consider $w(t)$ as Guassian random process, with $w(t)$ being $\mathcal{N}(\mu,\sigma)$ and i.i.d for all t. I consider applying a (stochastic)derivative operation to the random p …
2
votes
2answers
128 views

equivalence of 1-norm and relative entropy?

For two pmf $p=\lbrace p_i\rbrace$ and $q=\lbrace q_i\rbrace$ on the same finite alphabet, we know that relateive entropy $D(p\|q)=\sum p_i\log\frac{p_i}{q_i}$ and 1-norm $\|p-q\|_ …

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