On the affine rectification of convex curves (Q1591726)

As an affine analogue to the rectification of curves (polygonal approximation) in the plane, Pick and Blaschke considered a plane convex curve and its approximation in terms of segments of parabolas (curves with vanishing affine curvature). Under differentiability assumptions, Blaschke proved that this affine rectification process gives the same arc length as the usual definition using the Euclidean curvature. It is the main result of the paper under review that one can omit the differentiability assumptions.