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6.28318531
6.28318531 is offline
#3
Mar6-12, 04:19 AM
P: 55
Sorry M=R?

So the infinite collection would be open balls all ""stacked up"" inside each other, then they would all intersect, and that intersection would be closed, you could never get outside of the smallest ball, even though they are all open, you can keep on choosing a smaller ball? I can visualise what's happening, but how do you write that, do you use the definition of the open ball, and set d(0,x) <1/i ?