第二可数T3空间中正则开代数的 sober 性
Sobriety of Regular Open Algebras in Second-Countable T3 Spaces
AI总结:
该研究针对第二可数T3空间,揭示正则开代数RO(X)的Scott空间为sober的充要条件,由此解答完全布尔代数sober性的公开问题,并提供构造非sober完全格的系统方法。
AI中文摘要:
对于拓扑空间X,令RO(X)为X的正则开子集构成的完全布尔代数,按包含关系排序。我们证明:对每个第二可数T3空间X,RO(X)的Scott空间是 sober 当且仅当X的所有孤立点构成的集合在X中稠密。由此可得,对每个正整数n,RO(ℝⁿ)不是 sober 的;特别地,RO(ℝ)不是 sober 的,这为关于完全布尔代数的 sober 性的一个公开问题提供了答案。该刻画还给出了一种系统方法,可得到更多Scott空间非 sober 的完全格的自然实例。
英文摘要:
For a topological space X, let RO(X) be the complete Boolean algebra of regular open subsets of X, ordered by inclusion. We prove that, for every second-countable T3 space X, the Scott space of RO(X) is sober if and only if the set of all isolated points of X is dense in X. Consequently, RO$(\mathbb R^n)$ is not sober for every positive integer $n$. In particular, RO$(\mathbb R)$ is not sober, which provides an answer to an open problem concerning the sobriety of complete Boolean algebras. This characterization also yields a systematic way to obtain more natural examples of complete lattices whose Scott spaces are non-sober.