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Small holding circles

A circle C holds a convex body K if C does not meet the interior of K and if there does not exist any euclidean displacement which moves C as far as desired from K, avoiding the interior of K. The purpose of this note is to explore how small can be a holding circle. In particular it is shown that the diameter of such a holding circle can be less than the width w of the body but is always greater than 2w/3.