- #1
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What would be an example of two closed subspaces of a normed (or Banach) space whose sum A+B = {a+b: a in A, b in B} is not closed?
I suppose we would have to look in infinite dimensional space to find our example, because this is hard to imagine in R^n!
I suppose we would have to look in infinite dimensional space to find our example, because this is hard to imagine in R^n!