= Projective frame
{title2=$n+2\text{ points in }\mathbb P^n(\mathbb F)$}
An ordered projective frame consists of $n+2$ <projective points> such that any $n+1$ representative vectors are linearly independent. After mapping the first $n+1$ points to the coordinate axes, the last point has every coordinate nonzero; rescaling those axes sends it to $[1:\cdots:1]$. This proves existence and uniqueness of the <projective transformation> carrying one ordered frame to another. In the <projective plane> a frame consists of four points, no three collinear.
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