On the specification property and synchronization of unique q-expansions

Given a positive integer M and $q \in (1, M+1]$ we consider expansions in base q for real numbers $x \in [0, {M}/{q-1}]$ over the alphabet $\{0, \ldots , M\}$ . In particular, we study some dynamical properties of the natural occurring subshift $(\boldsymbol{{V}}_q, \sigma )$ related to unique expansions in such base q. We characterize the set of $q \in \mathcal {V} \subset (1,M+1]$ such that $(\boldsymbol{{V}}_q, \sigma )$ has the specification property and the set of $q \in \mathcal {V}$ such that $(\boldsymbol{{V}}_q, \sigma )$ is a synchronized subshift. Such properties are studied by analysing the combinatorial and dynamical properties of the quasi-greedy expansion of q. We also calculate the size of such classes as subsets of $\mathcal {V}$ giving similar results to those shown by Blanchard [ 10 ] and Schmeling in [ 36 ] in the context of $\beta $ -transformations.

Topological and almost Borel universality for systems with the weak specification property

We show that systems with some specification properties are topologically or almost Borel universal, in the sense that any aperiodic subshift with lower entropy may be topologically or almost Borel embedded. This improves, with elementary tools, previous results of Quas and Soo [Ergodic universality of some topological dynamical systems. Trans. Amer. Math. Soc.368 (2016), 4137–4170].

Sensitivity and specification property of fuzzified dynamical systems

The main purpose of this paper is to further explore the complexity of fuzzified dynamical systems. Especially, we study several kinds of specification properties of Zadeh’s extension. Among other things, we discuss the “stronger” sensitivity on product dynamical systems of g-fuzzification. There are two major ingredients. Firstly, it is proved that the specification (respectively almost specification) property of the original system and its Zadeh’s extension is equivalent, when the original system has the shadowing property. Moreover, we study the [Formula: see text]-sensitivity (respectively multi-sensitivity) of g-fuzzification and its induced product dynamical system.

Some dynamical properties for free semigroup actions

In this paper, we introduce the notions of weakly mixing and totally transitivity for a free semigroup action. Let [Formula: see text] be a free semigroup acting on a compact metric space generated by continuous open self-maps. Assuming shadowing for [Formula: see text] we relate the average shadowing property of [Formula: see text] to totally transitivity and its variants. Also, we study some properties such as mixing, shadowing and average shadowing properties, transitivity, chain transitivity, chain mixing and specification property for a free semigroup action.