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The standard n-ball is
 , where
 . The standard n-ball is also called the unit n-ball or the n-disk.
The notation in the literature for the standard n-ball is not uniform. Sometimes it is denoted by  ,  , or
 .
The boundary of the standard n-ball is  , the n-1-sphere.
A space that is homeomorphic to the standard n-ball is called an n-cell.
A 1-cell is called an arc and a 2-cell is called a disk.
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