If X = U{Xn: N} is a regular space, Xn has aσ-locally finite PF-regular closed net, and Xn is a closed subset of X for each n N, then X has a σ-locally finite PP-regular closed net;
文摘If X = U{Xn: N} is a regular space, Xn has aσ-locally finite PF-regular closed net, and Xn is a closed subset of X for each n N, then X has a σ-locally finite PP-regular closed net;