Line Segment
A closed interval corresponding to a finite portion of an infinite line. Line segments are generally labeled with
two letters corresponding to their endpoints, say 
and 
, and then written
. The length of the line segment is indicated with
an overbar, so the length of the line segment 
would be written
.
Curiously, the number of points in a line segment is equal to that in an entire one-dimensional space (a line), and also to the
number of points in an 
-dimensional space,
as first recognized by Georg Cantor.
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line segment
