Maximal independent sets, variants of chain/antichain principle and cofinal subsets without AC
In set theory without the axiom of choice (AC), we observe new relations of the following statements with weak choice principles.
In set theory without the axiom of choice (AC), we observe new relations of the following statements with weak choice principles.
We show that the existence of a non-trivial category base on a set of regular cardinality with each subset being Baire is equiconsistent to the existence of a measurable cardinal.
We prove that all groups can be realized as fundamental groups of compact spaces if and only if no measurable cardinals exist. If the cardinality of a group G is nonmeasurable then the compact space K such that G = π₁K may be chosen so that it is path connected.
Assuming the existence of a P₂κ-hypermeasurable cardinal, we construct a model of Set Theory with a measurable cardinal κ such that and the group Sym(κ) of all permutations of κ cannot be written as the union of a chain of proper subgroups of length < κ⁺⁺. The proof involves iteration of a suitably defined uncountable version of the Miller forcing poset as well as the “tuning fork” argument introduced by the first author and K. Thompson [J. Symbolic Logic 73 (2008)].
We show that the existence of measurable envelopes of all subsets of ℝⁿ with respect to the d-dimensional Hausdorff measure (0 < d < n) is independent of ZFC. We also investigate the consistency of the existence of -measurable Sierpiński sets.
We prove that the statement: "there is a Corson compact space with a non-separable Radon measure" is equivalent to a number of natural statements in set theory.
We consider the problem of finding a measurable unfriendly partition of the vertex set of a locally finite Borel graph on standard probability space. After isolating a sufficient condition for the existence of such a partition, we show how it settles the dynamical analog of the problem (up to weak equivalence) for graphs induced by free, measure-preserving actions of groups with designated finite generating set. As a corollary, we obtain the existence of translation-invariant random unfriendly colorings...
En este trabajo se realiza un estudio de Medidas de Nitidez para conjuntos difusos. Se comienza dando los conceptos de Medida Puntual de Nitidez o Auto-nitidez puntual y Medida de Nitidez para conjunto difuso, pasando a continuación a dar dos teoremas de construcción de Medidas de Nitidez y uno de caracterización para aquellas medidas que sean valoraciones en el retículo Ln(X).