A topological space (Χ,τ)is said to satisfy the second axiom of countability or to be second countable if there exists a basis βfor τ , where β consists of only a countable number of sets.
Let (Χ,τ)be the set of all integers with the finite-closed topology. Does the space (Χ,τ)satisfy the second axiom of countability?
可以這樣令嗎?
X=Z τ :finite-closed topology
τ = {O,Z,Z-{1},Z-{2},Z-{1,2},......}