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el Houcein el Abdalaoui

Publications and source records attributed to el Houcein el Abdalaoui.

25 records · Page 2Linked to original sources
arXiv2019

A note on actions with finite orbits on dendrites

It is shown that the restriction of the action of any group with finite orbit on the minimal sets of dendrites is equicontinuous. Consequently, we obtain that the action of any amenable group and Thompson group on dendrite restricted on minimal sets is equicontinuous. We further provide a class of non-amenable groups whose action on dendrites has finite orbit. We extend also some of our results to dendron. We further give a characterization of the set of invariant probability measures and its extreme points.

math.DS↗
arXiv2017

Oscillating sequences, Gowers norms and Sarnak's conjecture

It is shown that there is an oscillating sequence of higher order which is not orthogonal to the class of dynamical flow with topological entropy zero. We further establish that any oscillating sequence of order $d$ is orthogonal to any $d$-nilsequence arising from the skew product on the $d$-dimensional torus $\mathbb{T}^d$. The proof yields that any oscillating sequence of higher order is orthogonal to any dynamical sequence arising from topological dynamical systems with quasi-discrete spectrum. however, we provide an example of oscillating sequence of higher order with large Gowers norms. We further obtain a new estimation of the average of Möbius function on the short interval by appealing to Bourgain's double recurence argument.

math.DS↗
arXiv2017

On the Erdös flat polynomials problem, Chowla conjecture and Riemann Hypothesis

There are no square $L^2$-flat sequences of polynomials of the type $$\frac{1}{\sqrt q}( ε_0 + ε_1z + ε_2z^2 + \cdots + ε_{q-2}z^{q-2} +ε_q z^{q-1}),$$ where for each $j,~~ 0 \leq j\leq q-1,~ε_j = \pm 1$. It follows that Erdös's conjectures on Littlewood polynomials hold. Consequently, Turyn-Golay's conjecture is true, that is, there are only finitely many Barker sequences. We further get that the spectrum of dynamical systems arising from continuous Morse sequences is singular. This settles an old question due to M. Keane. Applying our reasoning to the Liouville function we obtain that the popular Chowla conjecture on the %Bernouillicity normality of the Liouville function implies Riemann hypothesis.

math.CO↗
arXiv2016

A cubic nonconventional ergodic average with multiplicative or Mangoldt weights

We show that the cubic nonconventional ergodic averages of any order with a bounded multiplicative function weight converge almost surely to zero provided that the multiplicative function satisfies a strong Daboussi-Delange condition. We further obtain that the Cesàro mean of the self-correlations and some moving average of the self-correlations of such multiplicative functions converge to zero. Our proof gives, for any $N \geq 2$, $$\frac1{N}\sum_{m=1}^{N}\Big|\frac1{N}\sum_{n=1}^{N} \bnu(n) \bnu(n+m)\Big| \leq \frac{C}{\log(N)^ε},$$ and $$\frac1{N^2}\sum_{n,p=1}^{N}\Big|\frac1{N}\sum_{m=1}^{N} \bnu(m) \bnu(n+m)\bnu(m+p)\bnu(n+m+p)\Big| \leq \frac{C}{\log(N)^{\varepsilon}},$$ where $C,\varepsilon$ are some positive constants and $\bnu$ is a bounded multiplicative function satisfying a Daboussi-Delange condition with logarithmic speed. We further establish that the cubic nonconventional ergodic averages of any order with Mangoldt weight converge almost surely provided that all the systems are nilsystems.

math.DS↗
arXiv2013

On the transition reduction problem for finite automata

We are interested in the problem of transition reduction of nondeterministic automata. We present some results on the reduction of the automata recognizing the language $L(E_n)$ denoted by the regular expression $E_n=(1+\varepsilon)... (2+\varepsilon)... (3+\varepsilon)... (n+\varepsilon)$. These results can be used in the general case of the transition reduction problem.

cs.FL↗
arXiv2012

On the spectral type of some class of rank one flows

It is shown that a certain class of Riesz product type measure on $\mathbb{R}$ is singular. This proves the singularity of the spectral types of some class of rank one flows. Our method is based on the extension of the Central Limit Theorem approach to the real line which gives a new extension of Salem-Zygmund Central Limit Theorem.

math.DS↗