In
mathematics, a
projective range is a set of points in
projective geometry considered in a unified fashion. A projective range may be a
projective line or a
conic. A projective range is the
dual of a
pencil of lines on a given point. For instance, a
correlation interchanges the points of a projective range with the lines of a pencil. A
projectivity is said to act from one range to another, though the two ranges may coincide as sets.