Proposition 2.33.e

Proposition 2.33.e: $$Cl(A) = (Int(A^c))^c$$.

Ian_mi
By proposition 2.33d, $$\text{Cl}(A)^c = \text{Cl}((A^c)^c)^c = \text{Int}(A^c)$$ so $$\text{Cl}(A) = \text{Int}(A^c)^c$$.

Ian mi 03:23, March 24, 2011 (UTC)Ian_mi