... 1).¹

In general, a point in an n-dimensional Euclidean space is represented as a point in an (n+1)-dimensional projective space.

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... ``line''²

Since it can become confusing to read statements such as, ``A point is represented as a `line,' '' we will always enclose in quotation marks the entities whose sole purpose is visualization in n+1 dimensions.

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... space,³

Do not be confused by the term space, which can refer to either three dimensions or an arbitrary number of dimensions.

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...$\ensuremath{{\bf y}}$,⁴

If $\ensuremath{{\bf t}} =\left[\matrix{a \cr b \cr c}\right]$, then $[\ensuremath{{\bf t}} ]_x = \left[\matrix{0 & -c & b \cr c & 0 & -a \cr -b & a & 0}\right]$.

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