首先构造一T2的亚紧空间使其不是任一仿紧T2空间的开紧映象,否定了A.Arhangel'skiǐ1962年提出的一个问题;其次利用构造开紧映射的方法指出存在具有Gδ对角线的T2的次亚紧空间使其不具有G^*δ对角线,肯定地回答了1999年R.Hodel提出的一个猜测.
In this paper, a question posed by A. Arhangel'skiǐ in 1962 is negatively answered by giving a T2 metacompact space which is not any open and compact image of a T2 paracompact space; and a conjecture posed by R. Hodel in 1999 is affirmatively answered by showing a T2 submetacompact space with Gδ-diagonal which is not of G^*δ-diagonal.