Alas, for any particular i and n, the set
Vi, n
is at most countable, because distinct points (x, 0)
and (y, 0) of one Vi, n
must lie at least 2/n apart, as measured by |x – y|.
Indeed, whatever the points (x, 0)
and (y, 0) of Vi, n ,
the one thing that is certain about the value |x – y| is
that, of the three classically exhaustive possibilities
| |x – y| | = 0 , |
0 < | |x – y| |
< 2/n , |
| |x – y| |
> 2/n , |
only the first and third can subsist; for, were the second the case,
the section f must send the point at which the two intersecting fingers meet,
as the illustrations show, to a point in the double cover that lies at once
in both of the broken open Vs shown,
which is impossible, as those two broken open Vs are disjoint.
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