Disconnection in the Alexandroff duplicate


  • Papiya Bhattacharjee Florida Atlantic University
  • Michelle L. Knox Midwestern State University
  • Warren Wm. McGovern Florida Atlantic University




extremally disconnected space, Alexandroff duplicate, P-space


It was demonstrated in [2] that the Alexandroff duplicate of the Čech-Stone compactification of the naturals is not extremally disconnected. The question was raised as to whether the Alexandroff duplicate of a non-discrete extremally disconnected space can ever be extremally disconnected. We answer this question in the affirmative; an example of van Douwen is significant. In a slightly different direction we also characterize when the Alexandroff duplicate of a space is a P-space as well as when it is an almost P-space.


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Author Biographies

Papiya Bhattacharjee, Florida Atlantic University

Department of Mathematical Sciences

Warren Wm. McGovern, Florida Atlantic University

Professor of Mathematics
Wilkes Honors College


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How to Cite

P. Bhattacharjee, M. L. Knox, and W. W. McGovern, “Disconnection in the Alexandroff duplicate”, Appl. Gen. Topol., vol. 22, no. 2, pp. 331–344, Oct. 2021.