In: Advanced Math
Let q and p be natural numbers, and show that the metric on Rq+p is equivalent to the metric it has if we identify Rq+p with Rq × Rp.
We want to show, the metric topology on is equivalant to product topology of . We can identify points of and in natural way. Now pick . Take an open ball arround of radius . Now it contains points , such that . That is same as saying, Now, and . Take balls and of radius arround and . And consider . Now, belong to the product topology of .
contains all points such that and . Then in , . So, .
Next we need to show for , is a ball centered at of radius , and is a ball centered at of radius , we can find a real number , such that . Now, for , and for ,. With out loss of generality, let be minimum of . Then take . Then . That imply and . So, for this , .
So these two topologies are equivalant.