Articles of kolmogorov complexity

set of Kolmogorov-random strings is co-re

given RC = {x : C(x) ≥ |x|} is a set of Kolmogorov-random strings. How can I show that RC is co-re I have been reading this paper What Can be Efficiently Reduced to the Kolmogorov-Random Strings? which just says that we know that by Kum96 we know that RC is Co-re I was not […]

Does a random binary sequence almost always have a finite number of prime prefixes?

Does a random binary sequence almost always have a finite number of prime prefixes? Specifically, let $x = \sum_{1 \le i}{2^{-i} \cdot x_i}$ with $x_i \in \{0,1\}$ be a random real in $[0,1)$, $X_i = \sum_{0 \le j \le i}{2^{i-j} \cdot x_j}$, and $F(x) = \cup_{i}{\{X_i\}}$. How can we prove that F(x) almost certainly does […]

Kolmogorov complexity of sequence and its fragment

Is it possible that part of sequence is more complex than all sequence because the best way to encode it is to use the complete sequence and starting and ending positions of the fragment. Maybe, for example, string of hexadecimal digits of $\pi$. Or something else.

Does Chaitin's constant have infinitely many prime prefixes?

Define $f(n) = \lfloor 2^n \cdot \Omega \rfloor$, that is, $f(n)$ is the first $n$ bits of Chaitin’s constant interpreted as a number written in binary. I am trying to figure out if $f(n)$ can have infinitely many prime values. To show that it cannot, it would suffice to find a way of compressing these […]

Prove that bitstrings with 1/0-ratio different from 50/50 are compressable

I’m looking for a proof, that $$ \sum_{i=0}^{\lambda n} \binom{n}{i} \le 2^{nH(\lambda)} $$ with $n>0$, $0 \le \lambda \le 1/2$ and $ H(\lambda)=-[\lambda log \lambda + (1-\lambda) log (1-\lambda)] $. Context: This shows, that if there is a bitstring with a ratio of ones and zeros (‘pick i from n’ where i is smaller than […]