Universality of Uniform Eberlein Compacta
نویسندگان
چکیده
We prove that if μ+ < λ = cf(λ) < μא0 for some regular μ > 2א0 , then there is no family of less than μא0 c-algebras of size λ which are jointly universal for c-algebras of size λ. On the other hand, it is consistent to have a cardinal λ ≥ א1 as large as desired and satisfying λ<λ = λ and 2λ + > λ++, while there are λ++ c-algebras of size λ+ that are jointly universal for calgebras of size λ+. Consequently, by the known results of M. Bell, it is consistent that there is λ as in the last statement and λ++ uniform Eberlein compacta of weight λ+ such that at least one among them maps onto any Eberlein compact of weight λ+ (we call such a family universal). The only positive universality results for Eberlein compacta known previously required the relevant instance of GCH to hold. These results complete the answer to a question of Y. Benyamini, M. E. Rudin and M. Wage from 1977 who asked if there always was a universal uniform Eberlein compact of a given weight.
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