Conformal iterated function systems with applications to the geometry of continued fractions

In this paper we obtain some results about general conformal iterated function systems. We obtain a simple characterization of the packing dimension of the limit set of such systems and introduce some special systems which exhibit some interesting behavior. We then apply these results to the set of values of real continued fractions with restricted entries. We pay special attention to the Hausdorff and packing measures of these sets. We also give direct interpretations of these measure theoretic results in terms of the arithmetic density properties of the set of allowed entries.

     

Invariant measures for parabolic IFS with overlaps and random continued fractions

We study parabolic iterated function systems (IFS) with overlaps on the real line. An ergodic shift-invariant measure with positive entropy on the symbolic space induces an invariant measure on the limit set of the IFS. The Hausdorff dimension of this measure equals the ratio of entropy over Lyapunov exponent if the IFS has no ``overlaps.' We focus on the overlapping case and consider parameterized families of IFS, satisfying a transversality condition. Our main result is that the invariant measure is absolutely continuous for a.e. parameter such that the entropy is greater than the Lyapunov exponent. If the entropy does not exceed the Lyapunov exponent, then their ratio gives the Hausdorff dimension of the invariant measure for a.e. parameter value, and moreover, the local dimension of the exceptional set of parameters can be estimated. These results are applied to a family of random continued fractions studied by R. Lyons. He proved singularity above a certain threshold; we show that this threshold is sharp and establish absolute continuity for a.e. parameter in some interval below the threshold.

     

Transient solutions of Markov processes and generalized continued fractions

In 1974 J. A. Murphy and M. R. O'Donohoe numerically approximatedthe minimal solution of the Kolmogorov forward equation forthe generalized birth and death process by use of continuedfractions. This paper generalizes this approach by suggestingan algorithm for q-matrices of lower band structure (n, 1).This is achieved by analogy with generalized continued fractions.Applications involving q-matrices of this type include, forexample, many types of queueing systems with batch processingor birth–death–catastrophe population processesin biology.     

Note on packing and weak-packing measures with Hausdorff functions

For every Hausdorff function we construct a compact metric space of finite positive weak-packing measure. Also we prove that for every non-doubling Hausdorff function there exists a compact metric space on which the packing and weak-packing measures are not equivalent.     

The fractal dimensions of the level sets of the generalized iterated Brownian motion

Let{W1(t), t∈R+} and {W2(t), t∈R+} be two independent Brownian motions with W1(0) = W2(0) = 0. {H (t) = W1(|W2(t)|), t ∈R+} is called a generalized iterated Brownian motion. In this paper, the Hausdorff dimension and packing dimension of the level sets {t ∈[0, T ], H(t) = x} are established for any 0 < T ≤ 1.     

Conformal measures and Hausdorff dimension for infinitely renormalizable quadratic polynomials

We show in this paper that iff is a quadratic infinitely many times renormalizable polynomial of sufficient high combinatorial type, then: HD (J(f))= inf{: -conformal measure for f} We use Lyubich's construction of the principal nest ([Lyu97]) in order to prove this result.Partially supported by CNP q-Brazil grant # 300534/96-5     

非对称Cantor集的Hausdorff中心测度

§ 1　 IntroductionThe class of Cantor sets is a typical one of sets in fractal geometry.Mathematicianshave paid their attentions to such sets for a long time.Itis well known that the Hausdorffmeasure of the Cantor middle- third set is1(see[1]) .Recently,Feng[3] obtained the exactvalues of the packing measure for a class of linear Cantor sets.Using Feng s method,Zhuand Zhou[5] obtained the exactvalue of Hausdorff centred measure of the symmetry Cantorsets.In this papar,we consider the Ha…     

An algorithm of infinite sums representations and Tasoev continued fractions

For any given real number, its corresponding continued fraction is unique. However, given an arbitrary continued fraction, there has been no general way to identify its corresponding real number. In this paper we shall show a general algorithm from continued fractions to real numbers via infinite sums representations. Using this algorithm, we obtain some new Tasoev continued fractions.

     

Coding of geodesics on some modular surfaces and applications to odd and even continued fractions

The connection between geodesics on the modular surface $PSL(2,\mathbb{Z})?\mathbb{H}$ and regular continued fractions, established by Series, is extended to a connection between geodesics on $\Gamma ?\mathbb{H}$ and odd and grotesque continued fractions, where $\Gamma ?{\mathbb{Z}}_{3}1{\mathbb{Z}}_3$ is the index two subgroup of $PSL(2,\mathbb{Z})$ generated by the order three elements $\left(\begin{array}{cc}\hfill 0\hfill & \hfill ?1\hfill \\ \hfill 1\hfill & \hfill 1\hfill \end{array}\right)$ and $\left(\begin{array}{cc}\hfill 0\hfill & \hfill 1\hfill \\ \hfill ?1\hfill & \hfill 1\hfill \end{array}\right)$, and having an ideal quadrilateral as fundamental domain.A similar connection between geodesics on $\Theta ?\mathbb{H}$ and even continued fractions is discussed in our framework, where $\Theta$ denotes the Theta subgroup of $PSL(2,\mathbb{Z})$ generated by $\left(\begin{array}{cc}\hfill 0\hfill & \hfill ?1\hfill \\ \hfill 1\hfill & \hfill 0\hfill \end{array}\right)$ and $\left(\begin{array}{cc}\hfill 1\hfill & \hfill 2\hfill \\ \hfill 0\hfill & \hfill 1\hfill \end{array}\right)$.     

广义Cantor集的自相似性

本文考虑一类广义Cantor集Γ_(β,の)={∞∑n=1dnβn:dn∈Dn,n≥1}的自相似性,其中0β1且对任意的n≥1,D_n为整数集Z的非空有限子集;并且给出Γ_(β,の)为齐次生成自相似集的充分必要条件.作为应用,本文考虑一类广义Cantor集交的自相似性,部分推广了Li,Yao和Zhang(2011)关于自相似性的结果.     

The packing measure of a class of generalized sierpinski carpet

For 1/4 ＜ a ＜√2/4, let S1(x) = ax, S2(x) = 1 - a ax, x ∈ [0,1]. Ca is the attractor of the iterated function system {S1, S2}, then the packing measure of Ca × Ca is Ps(a)(Ca × Ca) = 4.2s(a)(1 - a)s(a),where s(a) = -loga4.     

均匀三部分康托集的Hausdorff中心测度

均匀三部分康托集K(λ,3)是满足开集条件的自相似分形集．本文通过一个概率测度μ在点x的上球密度的计算给出了K(λ,3)的s维Hausdorff中心测度的精确值,其中s=logλ1/3是K(λ,3)的Hausdorff维数．     

Singularity of self-similar measures with respect to Hausdorff measures

Besicovitch (1934) and Eggleston (1949) analyzed subsets of points of the unit interval with given frequencies in the figures of their base- expansions. We extend this analysis to self-similar sets, by replacing the frequencies of figures with the frequencies of the generating similitudes. We focus on the interplay among such sets, self-similar measures, and Hausdorff measures. We give a fine-tuned classification of the Hausdorff measures according to the singularity of the self-similar measures with respect to those measures. We show that the self-similar measures are concentrated on sets whose frequencies of similitudes obey the Law of the Iterated Logarithm.

     

Hausdorff Dimensions of Self-Similar and Self-Affine Fractals in the Heisenberg Group

We study the Hausdorff dimensions of invariant sets for self-similarand self-affine iterated function systems in the Heisenberggroup. In our principal result we obtain almost sure formulaefor the dimensions of self-affine invariant sets, extendingto the Heisenberg setting some results of Falconer and Solomyakin Euclidean space. As an application, we complete the proofof the comparison theorem for Euclidean and Heisenberg Hausdorffdimension initiated by Balogh, Rickly and Serra-Cassano. 2000Mathematics Subject Classification 22E30, 28A78 (primary), 26A18,28A78 (secondary).     

Topological measures,image transformations and self-similar sets

Summary This paper introduces a novel idea: the concept of an image transformation. We also introduce the closely related concept of a quasi-homomorphism, and study the properties of these mathematical objects, and give several examples. In particular we investigate iterated systems of image transformations, which we believe give a more realistic approach to the study of so called self-similar structures in nature than what is obtained by iterated function systems.