δ-closed

Last-modified: 2011-11-11 (金) 14:50:46

Definition

  • The complement of δ-open set is called a δ-closed set.

Property

  • A subset A of (X,τ) is δ-closed if and only if imgtex.fcgi?%5bres=100%5d%7b%5c%5b%20A=%5crm%7bCl%7d_%7b%5cdelta%7d%28A%29:=%5c%7bx%5cin%20X%5c%20%7c%5c%20%5crm%7bInt%7d%28%5crm%7bCl%7d%28U%29%29%5ccap%20A%5cneq%5cemptyset%2c%20U%5cin%5ctau%5cmbox%7b%20and%20%7dx%5cin%20U%5c%7d%20%5c%5d%7d%25.png .

Reference

  • Caldas, M.; Ganster, M.; Georgiou, D. N.; Jafari, S.; Moshokoa, S. P., δ-semiopen sets in topology. (English summary), Proceedings of the 19th Summer Conference on Topology and its Applications., Topology Proc. 29 (2005), no. 2, 369–383.