Boolean Monomial Dynamical Systems

An important problem in the theory of finite dynamical systems is to link the structure of a system with its dynamics. This paper contains such a link for a family of nonlinear systems over the field with two elements. For systems that can be described by monomials (including Boolean AND systems), one can obtain information about the limit cycle structure from the structure of the monomials. In particular, the paper contains a sufficient condition for a monomial system to have only fixed points as limit cycles. This condition depends on the cycle structure of the dependency graph of the system and can be verified in polynomial time.Received February 2, 2004     

Interaction cohomology of forward or backward self-similar systems

We investigate the dynamics of forward or backward self-similar systems (iterated function systems) and the topological structure of their invariant sets. We define a new cohomology theory (interaction cohomology) for forward or backward self-similar systems. We show that under certain conditions, the space of connected components of the invariant set is isomorphic to the inverse limit of the spaces of connected components of the realizations of the nerves of finite coverings U of the invariant set, where each U consists of (backward) images of the invariant set under elements of finite word length. We give a criterion for the invariant set to be connected. Moreover, we give a sufficient condition for the first cohomology group to have infinite rank. As an application, we obtain many results on the dynamics of semigroups of polynomials. Moreover, we define postunbranched systems and we investigate the interaction cohomology groups of such systems. Many examples are given.     

On almost periodic orbits and minimal sets

In this short note we solve in the negative the three problems recently posed by Jie-Hua Mai and Wei-Hua Sun regarding the behaviour of almost periodic orbits and minimal sets of dynamical systems whose phase space is not regular.     

On Dynamics Related to a Class of Numeration Systems

 In this paper, we investigate the class of numeration systems and we study the associated dynamical systems, called odometers. It is shown that these odometers are measure-theoretically isomorphic to rank one transformations on the unit interval, constructed by a cutting-stacking method. Furthermore, a symbolic coding leads to isomorphic shift systems arising from substitutions. Some skew products of the odometers by cocycles related to the sum of digits are shown to be ergodic. Received 5 March 2001; in revised form 16 August 2001     

Diophantine Analysis of Conformal Iterated Function Systems

 A formula for the Hausdorff dimension of a subset of the limit set of a conformal infinite iterated function system is derived and expressed as a unique zero of the topological pressure of corresponding strongly H?lder family of functions. Received August 10, 2001; in revised form February 23, 2002     

Semicocycle extensions and the stroboscopic property

We indicate a large class of almost 1-1 extensions over minimal systems, which do not possess the stroboscopic property, as defined by Misiurewicz and studied by Jimenez and Snoha [Topology Appl. 129 (2003) 301-316]. Sturmian flows and all Toeplitz flows belong to this class. This generalizes a theorem of [Topology Appl. 129 (2003) 301-316] for Sturmian flows. Our result allows to easily construct minimal weakly mixing systems without the stroboscopic property, which answers in the negative a question posed in [Topology Appl. 129 (2003) 301-316]. Finally we prove that even the strong stroboscopic property does not imply the stroboscopic property for induced (first return time) systems.     

About the separability of completely integrable quasi-bi-Hamiltonian systems with compact levels

We study completely integrable quasi-bi-Hamiltonian systems whose common level surfaces are compact and prove in particular their separability in the sense of Falqui and Pedroni.     

Limit sets and the Poincaré-Bendixson Theorem in impulsive semidynamical systems

We consider semidynamical systems with impulse effects at variable times and we discuss some properties of the limit sets of orbits of these systems such as invariancy, compactness and connectedness. As a consequence we obtain a version of the Poincaré-Bendixson Theorem for impulsive semidynamical systems.     

Chaos and the shadowing property

We present, as a simpler alternative for the results of [P. Ko?cielniak, On genericity of shadowing and periodic shadowing property, J. Math. Anal. Appl. 310 (2005) 188-196; P. Ko?cielniak, M. Mazur, On C⁰ genericity of various shadowing properties, Discrete Contin. Dynam. Syst. 12 (2005) 523-530], an elementary proof of C⁰ genericity of the periodic shadowing property. We also characterize chaotic behavior (in the sense of being semiconjugated to a shift map) of shadowing systems.     

Strong centers of attraction for multi-valued dynamical systems on noncompact spaces

In this article, we introduce the notions of strong centers of attraction for multi-valued dynamical systems on arbitrary metric spaces. And we obtain strong centers of attraction for multi-valued dynamical systems.     

Studying discrete dynamical systems through differential equations

In this paper we consider dynamical systems generated by a diffeomorphism F defined on U an open subset of Rn, and give conditions over F which imply that their dynamics can be understood by studying the flow of an associated differential equation, , also defined on U. In particular the case where F has n−1 functionally independent first integrals is considered. In this case X is constructed by imposing that it shares with F the same set of first integrals and that the functional equation μ(F(x))=det(DF(x))μ(x), x∈U, has some non-zero solution, μ. Several examples for n=2,3 are presented, most of them coming from several well-known difference equations.     

Bifurcation and chaos near sliding homoclinics

We study the chaotic behaviour of a time dependent perturbation of a discontinuous differential equation whose unperturbed part has a sliding homoclinic orbit that is a solution homoclinic to a hyperbolic fixed point with a part belonging to a discontinuity surface. We assume the time dependent perturbation satisfies a kind of recurrence condition which is satisfied by almost periodic perturbations. Following a functional analytic approach we construct a Melnikov-like function M(α) in such a way that if M(α) has a simple zero at some point, then the system has solutions that behave chaotically. Applications of this result to quasi-periodic systems are also given.     

Coding and tiling of Julia sets for subhyperbolic rational maps

Let be a subhyperbolic rational map of degree d. We construct a set of “proper” coding maps Cod^°(f)={π_r:Σ→J}_r of the Julia set J by geometric coding trees, where the parameter r ranges over mappings from a certain tree to the Riemann sphere. Using the universal covering space for the corresponding orbifold, we lift the inverse of f to an iterated function system I=(g_i)_i=1,2,…,d. For the purpose of studying the structure of Cod^°(f), we generalize Kenyon and Lagarias-Wang's results : If the attractor K of I has positive measure, then K tiles φ^-1(J), and the multiplicity of π_r is well-defined. Moreover, we see that the equivalence relation induced by π_r is described by a finite directed graph, and give a necessary and sufficient condition for two coding maps π_r and π_r^′ to be equal.     

On limit behavior of skew‐product transformation semigroups

This paper introduces both the notions of topological transitivity and topological mixing in the general setting of semigroup actions on topological spaces. A discussion on limit behavior of skew‐product transformation semigroups is presented. The main purpose is to characterize the lifts and the projections of recurrent points, attractors and Morse decompositions for transformation semigroups associated to skew‐product transformation semigroups. The results play a role to the existence of the finest Morse decomposition for control systems and their control flows.     

Nonexistence of codimension one Anosov flows on compact manifolds with boundary

A flow is Anosov if it exhibits contracting and expanding directions forming with the flow a continuous tangent bundle decomposition. An Anosov flow is codimension one if its contracting or expanding direction is one-dimensional. Examples of codimension one Anosov flows on compact boundaryless manifolds can be exhibited in any dimension ?3. In this paper, we prove that there are no codimension one Anosov flows on compact manifolds with boundary. The proof uses an extension to flows of some results in Hirsch [On Invariant Subsets of Hyperbolic Sets, Essays on Topology and Related Topics, Memoires dédiés à Georges de Rham, 1970, pp. 126-135] related to Question 10(b) in Palis and Pugh [Fifty problems in dynamical systems, in: J. Palis, C.C. Pugh (Eds.), Dynamical Systems-Warwick 1974 (Proc. Sympos. Appl. Topology and Dynamical Systems, Univ. Warwick, Coventry, 1973/1974; presented to E.C. Zeeman on his fiftieth birthday), Lecture Notes in Mathematics, vol. 468, Springer, Berlin, 1975, pp. 345-353].     

Fluctuation between Subsets of Evolutions Governed by Chaotic Systems

Some issues on fluctuation of solutions to Lorenz and Rossler systems, for instance, are related to viability kernels of subsets under continuous time systems, or in the case of Julia sets, for instance, under discrete time systems. It happens that viability kernels of subsets, capture basins of targets and the combination of the twos provide tools for the analysis of the local behavior around equilibria (local stable and unstable manifolds), the asymptotic behavior and the functuation of evolutions between two areas of a domain, etc. Since algorithms and softwares do exist for computing the viability kernels and the capture basins, as well as evolutions viable in the viability kernel until they converge to a target infinite time, we are able to localize fluctuation basins.     

Heteroclinic Cycles in Coupled Systems of Difference Equations

Cycling behavior, in which solution trajectories linger around steady-states and periodic solutions, is known to be a generic feature of coupled cell systems of differential equations. In this type of systems, cycling behavior can even occur independently of the internal dynamics of each cell. This conclusion has lead to the discovery of "cycling chaos", in which solution trajectories cycle around symmetrically related chaotic sets. In this work, we demonstrate that cycling behavior also occurs in coupled systems of difference equations. More specifically, we prove the existence of structurally stable cycles between fixed points, and use numerical simulations to illustrate that the resulting cycles can also persist independently of the internal dynamics of each cell. Consequently, we demonstrate that cycles involving periodic orbits as well as cycling chaos also occur in systems of difference equations.     

Asymptotic almost-equivalence of Lipschitz evolution systems in Banach spaces

In this paper we introduce a notion of asymptotic almost-equivalence of two evolution systems and provide simple tests that guarantee that two evolution systems have the same qualitative asymptotic properties. In this way we are able to unify and extend many previously known results and also to understand what is behind equally behaved systems. In particular, we establish convergence, ergodic convergence and almost-convergence of almost-orbits both for the weak and the strong topologies based on the behavior of the orbits.