Q:Find two disjoint clsed subsets of (R^2) which are zero distance a part?

my answer is A & B where

A={(1/n) : n belong to z+}X{0}

B={[-1,0]XR}

Is it right

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- Aug 27th 2011, 05:23 PMrqeeb2 disjoint clsed subsets of (R^2)Q:Find two disjoint clsed subsets of (R^2) which are zero distance a part?

my answer is A & B where

A={(1/n) : n belong to z+}X{0}

B={[-1,0]XR}

Is it right

- Aug 27th 2011, 07:31 PMhatsoffRe: 2 disjoint clsed subsets of (R^2)
No, it is not correct. Notice that . So , and this set is not closed since is a boundary point not in .

However, consider the sets and . - Aug 27th 2011, 10:35 PMrqeebRe: 2 disjoint clsed subsets of (R^2)
- Aug 28th 2011, 05:09 AMhatsoffRe: 2 disjoint clsed subsets of (R^2)
D is a set, not a point. So D could not possibly *be* a boundary point.

Think of it graphically: C is just the curve y=1/x in the first quadrant of the plane. D is the line y=0.