No Arabic abstract
Associated to a IFS one can consider a continuous map $hat{sigma} : [0,1]times Sigma to [0,1]times Sigma$, defined by $hat{sigma}(x,w)=(tau_{X_{1}(w)}(x), sigma(w))$ were $Sigma={0,1, ..., d-1}^{mathbb{N}}$, $sigma: Sigma to Sigma$ is given by$sigma(w_{1},w_{2},w_{3},...)=(w_{2},w_{3},w_{4}...)$ and $X_{k} : Sigma to {0,1, ..., n-1}$ is the projection on the coordinate $k$. A $rho$-weighted system, $rho geq 0$, is a weighted system $([0,1], tau_{i}, u_{i})$ such that there exists a positive bounded function $h : [0,1] to mathbb{R}$ and probability $ u $ on $[0,1]$ satisfying $ P_{u}(h)=rho h, quad P_{u}^{*}( u)=rho u$. A probability $hat{ u}$ on $[0,1]times Sigma$ is called holonomic for $hat{sigma}$ if $ int g circ hat{sigma} dhat{ u}= int g dhat{ u}, forall g in C([0,1])$. We denote the set of holonomic probabilities by ${cal H}$. Via disintegration, holonomic probabilities $hat{ u}$ on $[0,1]times Sigma$ are naturally associated to a $rho$-weighted system. More precisely, there exist a probability $ u$ on $[0,1]$ and $u_i, iin{0, 1,2,..,d-1}$ on $[0,1]$, such that is $P_{u}^*( u)= u$. We consider holonomic ergodic probabilities. For a holonomic probability we define entropy. Finally, we analyze the problem: given $phi in mathbb{B}^{+}$, find the solution of the maximization pressure problem $$p(phi)=$$
In this note, we show several variational principles for metric mean dimension. First we prove a variational principles in terms of Shapiras entropy related to finite open covers. Second we establish a variational principle in terms of Katoks entropy. Finally using these two variational principles we develop a variational principle in terms of Brin-Katok local entropy.
In this article, we introduce a notion of relative mean metric dimension with potential for a factor map $pi: (X,d, T)to (Y, S)$ between two topological dynamical systems. To link it with ergodic theory, we establish four variational principles in terms of metric entropy of partitions, Shapiras entropy, Katoks entropy and Brin-Katok local entropy respectively. Some results on local entropy with respect to a fixed open cover are obtained in the relative case. We also answer an open question raised by Shi cite{Shi} partially for a very well-partitionable compact metric space, and in general we obtain a variational inequality involving box dimension of the space. Corresponding inner variational principles given an invariant measure of $(Y,S)$ are also investigated.
Conformal geodesics are solutions to a system of third order of equations, which makes a Lagrangian formulation problematic. We show how enlarging the class of allowed variations leads to a variational formulation for this system with a third--order conformally invariant Lagrangian. We also discuss the conformally invariant system of fourth order ODEs arising from this Lagrangian, and show that some of its integral curves are spirals.
The four equations of stellar structure are reformulated as two alternate pairs of variational principles. Different thermodynamic representations lead to the same hydromechanical equations, but the thermal equations require, not the entropy, but the temperature as the thermal field variable. Our treatment emphasizes the hydrostatic energy and the entropy production rate of luminosity produced and transported. The conceptual and calculational advantages of integral over differential formulations of stellar structure are discussed along with the difficulties in describing stellar chemical evolution by variational principles.
We introduce an axiomatic approach to entropies and relative entropies that relies only on minimal information-theoretic axioms, namely monotonicity under mixing and data-processing as well as additivity for product distributions. We find that these axioms induce sufficient structure to establish continuity in the interior of the probability simplex and meaningful upper and lower bounds, e.g., we find that every relative entropy must lie between the Renyi divergences of order $0$ and $infty$. We further show simple conditions for positive definiteness of such relative entropies and a characterisation in term of a variant of relative trumping. Our main result is a one-to-one correspondence between entropies and relative entropies.