关于δθ-加细空间的有限并及CP—netted空间的可数并定理

摘要

It is proved that a space of countable extent is LindelSf if it is the union of finitely many δθ-refinable subspaces. It answers two problems raised by Arhangel'skii and Buzyakova affirmatively. It is also proved that a stratifiable space is CP-netted if it is the union of countably many CP-netted closed subspaces.%本文通过证明可表示为有限多个δθ-加细空间的并同时具有可数散度的空间是Lin—delof空间，正面回答了Arhangel’skii与Buzyakova提出的两个问题．另外，本文证明了可表示为可数多个CP—netted闭子空间的并的层空间是CP—netted空间．