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Jianjie Zhao

Publications and source records attributed to Jianjie Zhao.

11 recordsLinked to original sources
arXiv2026

Density properties of orbits for a hypercyclic operator on a Banach space

We study density properties of orbits for a hypercyclic operator $T$ on a separable Banach space $X$, and show that exactly one of the following four cases holds: (1) every vector in $X$ is asymptotic to zero with density one; (2) generic vectors in $X$ are distributionally irregular of type $1$; (3) generic vectors in $X$ are distributionally irregular of type $2\frac{1}{2}$ and no hypercyclic vector is distributionally irregular of type $1$; (4) every hypercyclic vector in $X$ is divergent to infinity with density one. We also present some examples concerned with weighted backward shifts on $\ell^p$ to show that all the above four cases can occur. Furthermore, we show that similar results hold for $C_0$-semigroups.

math.FA↗
arXiv2026

Nil-Bohr Sets and Sums with Bounded Gaps

We study the relation between $\NilBohr{d}$ sets and $\SG_d^*$ sets. We prove that every $\NilBohr{d}$ set is an $\SG_d^*$ set, answering a question of Host and Kra. More generally, for a compact Hausdorff distal system whose Ellis group admits a closed filtration \[ E=E_1\supseteq E_2\supseteq\cdots\supseteq E_{d+1}=\{e\}, \ [E_j,E]\subseteq E_{j+1}, \] we prove that every return time set is an $\SG_d^*$ set.

math.DS↗
arXiv2025

Mean Li-Yorke chaos for a sequence of operators on Banach spaces

In this paper, we obtain the dichotomy for mean equicontinuity and mean sensitivity for a sequence of bounded linear operators from a Banach space to a normed linear space. The mean Li-Yorke chaos for sequences and submultiplicative sequences of bounded linear operators are also studied. Furthermore, several criteria for mean Li-Yorke chaos are established.

math.FA↗
arXiv2024

Topologically mildly mixing of higher orders along generalized polynomials

This paper is devoted to studying the multiple recurrent property of topologically mildly mixing systems along generalized polynomials. We show that if a minimal system is topologically mildly mixing, then it is mild mixing of higher orders along generalized polynomials. Precisely, suppose that $(X, T)$ is a topologically mildly mixing minimal system, $d\in \mathbb{N}$, $p_1, \dots, p_d$ are integer-valued generalized polynomials with $(p_1, \dots, p_d)$ non-degenerate. Then for all non-empty open subsets $U , V_1, \dots, V_d $ of $X$, $$\{n\in \Z: U\cap T^{-p_1(n) }V_1 \cap \dots \cap T^{-p_d(n) }V_d \neq \emptyset \}$$ is an IP$^*$-set.

math.DS↗
arXiv2022

Minimal subsystems of given mean dimension in Bernstein spaces

In this paper, we study the shift on the space of uniformly bounded continuous functions band-limited in a given compact interval with the standard topology of tempered distributions. We give a constructive proof of the existence of minimal subsystems with any given mean dimension strictly less than twice its band-width. A version of real-valued function spaces is considered as well.

math.DS↗
arXiv2021

Null systems in the non-minimal case

In this paper, it is shown that if a dynamical system is null and distal, then it is equicontinuous. It turns out that a null system with closed proximal relation is mean equicontinuous. As a direct application, it follows that a null dynamical system with dense minimal points is also mean equicontinuous. Meanwhile, a distal system with trivial $\text{Ind}_{fip}$-pairs, and a non-trivial regionally proximal relation of order $\infty$ is constructed.

math.DS↗
arXiv2021

Top-nilpotent enveloping semigroups and pro-nilsystems

In this paper, it is shown that for $d\in\mathbb{N}$, a minimal system $(X,T)$ is a $d$-step pro-nilsystem if its enveloping semigroup is a $d$-step top-nilpotent group, answering an open question by Donoso. Thus, combining the previous result of Donoso, it turns out that a minimal system $(X,T)$ is a $d$-step pro-nilsystem if and only if its enveloping semigroup is a $d$-step top-nilpotent group.

math.DS↗
arXiv2020

Stable Central Limit Theorems for Super Ornstein-Uhlenbeck Processes, II

This paper is a continuation of our recent paper (Elect. J. Probab. 24 (2019), no. 141) and is devoted to the asymptotic behavior of a class of supercritical super Ornstein-Uhlenbeck processes $(X_t)_{t\geq 0}$ with branching mechanisms of infinite second moment. In the aforementioned paper, we proved stable central limit theorems for $X_t(f) $ for some functions $f$ of polynomial growth in three different regimes. However, we were not able to prove central limit theorems for $X_t(f) $ for all functions $f$ of polynomial growth. In this note, we show that the limit stable random variables in the three different regimes are independent, and as a consequence, we get stable central limit theorems for $X_t(f) $ for all functions $f$ of polynomial growth.

math.PR↗
arXiv2019

Stable Central Limit Theorems for Super Ornstein-Uhlenbeck Processes

In this paper, we study the asymptotic behavior of a supercritical $(ξ,ψ)$-superprocess $(X_t)_{t\geq 0}$ whose underlying spatial motion $ξ$ is an Ornstein-Uhlenbeck process on $\mathbb R^d$ with generator $L = \frac{1}{2}σ^2Δ- b x \cdot \nabla$ where $σ, b >0$; and whose branching mechanism $ψ$ satisfies Grey's condition and some perturbation condition which guarantees that, when $z\to 0$, $ψ(z)=-αz + ηz^{1+β} (1+o(1))$ with $α> 0$, $η>0$ and $β\in (0, 1)$. Some law of large numbers and $(1+β)$-stable central limit theorems are established for $(X_t(f) )_{t\geq 0}$, where the function $f$ is assumed to be of polynomial growth. A phase transition arises for the central limit theorems in the sense that the forms of the central limit theorem are different in three different regimes corresponding the branching rate being relatively small, large or critical at a balanced value.

math.PR↗
arXiv2018

A note on mean equicontinuity

In this note, it is shown that several results concerning mean equicontinuity proved before for minimal systems are actually held for general topological dynamical systems. Particularly, it turns out that a dynamical system is mean equicontinuous if and only if it is equicontinuous in the mean if and only if it is Banach (or Weyl) mean equicontinuous if and only if its regionally proximal relation is equal to the Banach proximal relation. Meanwhile, a relation is introduced such that the smallest closed invariant equivalence relation containing this relation induces the maximal mean equicontinuous factor for any system.

math.DS↗