Homogeneous sets of positive outer measure∗
نویسنده
چکیده
For every Polish space and a coanalytic set of its countable subsets, if there is a homogeneous set of outer measure one then there is a perfect homogeneous set. In the generic extension by a large measure algebra, if there is a homogeneous set of size continuum then there is a a perfect homogeneous set.
منابع مشابه
Hausdorff measure
Here, instead of taking a σ-algebra as given and then defining a measure on this σ-algebra (namely, on the measurable sets), we take an outer measure as given and then define measurable sets using this outer measure. Carathéodory’s theorem states that the collection M of ν-measurable sets is a σ-algebra and that the restriction of ν to M is a complete measure. Suppose that (X, ρ) is a metric sp...
متن کاملStochastic independence with respect to upper and lower conditional probabilities deined by Hausdorff outer and inner measures
A new model of coherent upper conditional prevision is proposed in a metric space. It is defined by the Choquet integral with respect to the s-dimensional Hausdorff outer measure if the conditioning event has positive and finite Hausdorff outer measure in its dimension s. Otherwise if the conditioning event has Hausdorff outer measure in its dimension equal to zero or infinity it is defined by ...
متن کاملSOME SIMILARITY MEASURES FOR PICTURE FUZZY SETS AND THEIR APPLICATIONS
In this work, we shall present some novel process to measure the similarity between picture fuzzy sets. Firstly, we adopt the concept of intuitionistic fuzzy sets, interval-valued intuitionistic fuzzy sets and picture fuzzy sets. Secondly, we develop some similarity measures between picture fuzzy sets, such as, cosine similarity measure, weighted cosine similarity measure, set-theoretic similar...
متن کاملOn effectively closed sets of effective strong measure zero
The strong measure zero sets of reals have been widely studied in the context of set theory of the real line. The notion of strong measure zero is straightforwardly effectivized. A set of reals is said to be of effective strong measure zero if for any computable sequence {εn}n∈N of positive rationals, a sequence of intervals In of diameter εn covers the set. We observe that a set is of effectiv...
متن کاملSum of Cantor Sets: Self-similarity and Measure
In this note it is shown that the sum of two homogeneous Cantor sets is often a uniformly contracting self-similar set and it is given a sufficient condition for such a set to be of Lebesgue measure zero (in fact, of Hausdorff dimension less than one and positive Hausdorff measure at this dimension). 1. Definitions and results The study of the arithmetic difference (sum) of two Cantor sets has ...
متن کامل