*Definition [#bbd58382] In a topological space, a subset A is called semiopen if &ref(http://www.eaflux.com/imgtex/imgtex.fcgi?%5bres=100%5d%7b$A%5csubset%5cmathrm%7bclint%7dA$%7d%25.png);.
*Definition [#bbd58382] In a topological space, a subset A is called semiopen if &ref(http://www.eaflux.com/imgtex/imgtex.fcgi?%5bres=100%5d%7b$A%5csubset%5cmathrm%7bclint%7dA$%7d%25.png);.