Kolmogorov complexity and Hausdorff dimension

Author(s):  
Ludwig Staiger
Computability ◽  
2021 ◽  
pp. 1-28
Author(s):  
Neil Lutz ◽  
D.M. Stull

This paper investigates the algorithmic dimension spectra of lines in the Euclidean plane. Given any line L with slope a and vertical intercept b, the dimension spectrum sp ( L ) is the set of all effective Hausdorff dimensions of individual points on L. We draw on Kolmogorov complexity and geometrical arguments to show that if the effective Hausdorff dimension dim ( a , b ) is equal to the effective packing dimension Dim ( a , b ), then sp ( L ) contains a unit interval. We also show that, if the dimension dim ( a , b ) is at least one, then sp ( L ) is infinite. Together with previous work, this implies that the dimension spectrum of any line is infinite.


2013 ◽  
Vol 78 (4) ◽  
pp. 1229-1246 ◽  
Author(s):  
Ian Herbert

AbstractWe examine a definition of the mutual information of two reals proposed by Levin in [5]. The mutual information iswhereK(·) is the prefix-free Kolmogorov complexity. A realAis said to have finite self-information ifI (A : A)is finite. We give a construction for a perfect Π10class of reals with this property, which settles some open questions posed by Hirschfeldt and Weber. The construction produces a perfect set of reals withK(σ)≤+KA(σ)+f (σ)for any given Δ20fwith a particularly nice approximation and for a specific choice of f it can also be used to produce a perfect Π10set of reals that are low for effective Hausdorff dimension and effective packing dimension. The construction can be further adapted to produce a single perfect set of reals that satisfyK(σ)≤+KA(σ)+f (σ)for allfin a ‘nice’ class of Δ20functions which includes all Δ20orders.


Author(s):  
Daniel Berend

AbstractLet σ be an ergodic endomorphism of the r–dimensional torus and Π a semigroup generated by two affine transformations lying above σ. We show that the flow defined by Π admits minimal sets of positive Hausdorff dimension and we give necessary and sufficient conditions for this flow to be minimal.


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