A problem of Klee on inner section functions of convex bodies

Abstract

In 1969, Vic Klee asked whether a convex body is uniquely determined (up to translation and reflection in the origin) by its inner section function, the function giving for each direction the maximal area of sections of the body by hyperplanes orthogonal to that direction. We answer this question in the negative by con- structing two infinitely smooth convex bodies of revolution about the $x_n$-axis in $\mathbb{R}^n, n\ge 3$, one origin symmetric and the other not centrally symmetric, with the same inner section function. Moreover, the pair of bodies can be arbitrarily close to the unit ball.