Abstract:
Let X be a space,and \mathscrP=
A∶
A is a subset of
X, and has property >\mathscrP.A space
X is dual the property \mathscrP if for any neighborhood assignment
φ for X,there is a subset
A⊂
X,A∈\mathscrP,such that
X=∪
φ(
x)∶
x∈A.In this note,we mainly discuss properties of spaces which are dually special \mathscrP,and also give a necessary and sufficient condition for spaces which are dually special \mathscrP.These conclusions can be held for many spaces.As a corollary,we have that if
X is a regular weak
θ-refinable(dually discrete)-scattered space,then
X is dually discrete.We also get some conclusions conserning
aD- spaces.