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On the dynamics of ϕ : x x p + a in a local field

David Adam, Youssef Fares (2010)

Actes des rencontres du CIRM

Let K be a local field, a K and ϕ : x x p + a where p denotes the characteristic of the residue field. We prove that the minimal subsets of the dynamical system ( K , ϕ ) are cycles and describe the cycles of this system.

On the entropy for group actions on the circle

Eduardo Jorquera (2009)

Fundamenta Mathematicae

We show that for a finitely generated group of C² circle diffeomorphisms, the entropy of the action equals the entropy of the restriction of the action to the non-wandering set.

On the entropy of Darboux functions

Ryszard J. Pawlak (2009)

Colloquium Mathematicae

We prove some results concerning the entropy of Darboux (and almost continuous) functions. We first generalize some theorems valid for continuous functions, and then we study properties which are specific to Darboux functions. Finally, we give theorems on approximating almost continuous functions by functions with infinite entropy.

On the envelope of a vector field

Bernard Malgrange (2011)

Banach Center Publications

Given a vector field X on an algebraic variety V over ℂ, I compare the following two objects: (i) the envelope of X, the smallest algebraic pseudogroup over V whose Lie algebra contains X, and (ii) the Galois pseudogroup of the foliation defined by the vector field X + d/dt (restricted to one fibre t = constant). I show that either they are equal, or the second has codimension one in the first.

On the ergodic decomposition for a cocycle

Jean-Pierre Conze, Albert Raugi (2009)

Colloquium Mathematicae

Let (X,,μ,τ) be an ergodic dynamical system and φ be a measurable map from X to a locally compact second countable group G with left Haar measure m G . We consider the map τ φ defined on X × G by τ φ : ( x , g ) ( τ x , φ ( x ) g ) and the cocycle ( φ ) n generated by φ. Using a characterization of the ergodic invariant measures for τ φ , we give the form of the ergodic decomposition of μ ( d x ) m G ( d g ) or more generally of the τ φ -invariant measures μ χ ( d x ) χ ( g ) m G ( d g ) , where μ χ ( d x ) is χ∘φ-conformal for an exponential χ on G.

On the existence of chaotic behaviour of diffeomorphisms

Michal Fečkan (1993)

Applications of Mathematics

For several specific mappings we show their chaotic behaviour by detecting the existence of their transversal homoclinic points. Our approach has an analytical feature based on the method of Lyapunov-Schmidt.

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