Large strongly anti-Urysohn spaces exist

نویسندگان

چکیده

As defined in [3], a Hausdorff space is strongly anti-Urysohn (in short: SAU) if it has at least two non-isolated points and any infinite closed subsets of intersect. Our main result answers the questions [3] by providing ZFC construction locally countable SAU cardinality 2c. The hinges on existence 2c weak P-points ω⁎, very deep Ken Kunen. It remains open spaces >2c could exist, while was shown that 22c an upper bound. Also, we do not know crowded spaces, i.e. ones without isolated points, exist but obtained following consistency results concerning such spaces. consistent c as large you wish there c+. both are For uncountable cardinal κ statements equivalent: κ=cof([κ]ω,⊆). There size generic extension adding Cohen reals. countably compact T1-space some CCC extension.

برای دانلود باید عضویت طلایی داشته باشید

برای دانلود متن کامل این مقاله و بیش از 32 میلیون مقاله دیگر ابتدا ثبت نام کنید

اگر عضو سایت هستید لطفا وارد حساب کاربری خود شوید

منابع مشابه

Weakly Continuously Urysohn Spaces

We study weakly continuously Urysohn spaces, which were introduced in [Z]. We show that every weakly continuously Urysohn w∆-space has a base of countable order, that separable weakly continuously Urysohn spaces are submetrizable, hence continuously Urysohn, that monontonically normal weakly continuously Urysohn spaces are hereditarily paracompact, and that no linear extension of any uncountabl...

متن کامل

Central subsets of Urysohn universal spaces

A subset A of a metric space (X, d) is central iff for every Katětov map f : X → R upper bounded by the diameter of X and any finite subset B of X there is x ∈ X such that f(a) = d(x, a) for each a ∈ A ∪ B. Central subsets of the Urysohn universal space U (see introduction) are studied. It is proved that a metric space X is isometrically embeddable into U as a central set iff X has the collinea...

متن کامل

Properly forking formulas in Urysohn spaces

In this informal note, we demonstrate the existence of forking and nondividing formulas in continuous theory of the complete Urysohn sphere, as well as the discrete theories of the integral Urysohn spaces of diameter n (where n ≥ 3). Whether or not such formulas existed was asked in thesis work of the author, as well as joint work with Terry. We also show an interesting phenomenon in that, for ...

متن کامل

Strongly k-spaces

‎In this paper‎, ‎we introduce the notion of strongly $k-$spaces (with the weak (=finest) pre-topology generated by their strongly compact subsets)‎. ‎We characterize the strongly $k-$spaces and investigate the relationships between preclosedness‎, ‎locally strongly compactness‎, ‎pre-first countableness and being strongly $k-$space.

متن کامل

Fréchet-urysohn Spaces in Free Topological Groups

Let F (X) and A(X) be respectively the free topological group and the free Abelian topological group on a Tychonoff space X. For every natural number n we denote by Fn(X) (An(X)) the subset of F (X) (A(X)) consisting of all words of reduced length ≤ n. It is well known that if a space X is not discrete, then neither F (X) nor A(X) is Fréchet-Urysohn, and hence first countable. On the other hand...

متن کامل

ذخیره در منابع من


  با ذخیره ی این منبع در منابع من، دسترسی به آن را برای استفاده های بعدی آسان تر کنید

ژورنال

عنوان ژورنال: Topology and its Applications

سال: 2023

ISSN: ['1879-3207', '0166-8641']

DOI: https://doi.org/10.1016/j.topol.2022.108288