h***i
发帖数: 68 | 1 First of all, I think that the part a. of this problem is
not so hard. If you realy have difficulty in this question,
I will give you an answer later.
But I think that the questions b. to d. seem to be wrong.
Here I'll give you an contrexample:
I take X to be the set of real numbres with the normal
metric. And Y be the set of real numbres with the metric
d(u,v)=2. It is not difficult to verify that X and Y are all
complete metric spaces.
Now let O=X*Y\{(x,x)|x in R}. It is obvious that O is a
de |
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