Suppose that is an infinite set with the co-finite topology, and . Find in the cases where

(a) finite and (b) infinite.

I really dont know where to start. Hints would be very useful.

Thanks

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- September 13th 2011, 11:35 AMFGT12find the closure of A in the co-finite topology
Suppose that is an infinite set with the co-finite topology, and . Find in the cases where

(a) finite and (b) infinite.

I really dont know where to start. Hints would be very useful.

Thanks - September 13th 2011, 11:54 AMgirdavRe: find the closure of A in the co-finite topology
Hint: the closed set are the finite subsets of X and X.

- September 13th 2011, 11:55 AMPlatoRe: find the closure of A in the co-finite topology