The Cauchy-Crofton formula and the Whitney arc property for definable sets

Abstract

We use the Cauchy-Crofton formula to show that every definable cell (bounded by a ball with rational radius) in an O-minimal expansion of a field extension of the real numbers satisfies the Whitney arc property.

8 pages, This paper has been withdrawn by the author. The third sentence of the proof of Theorem 5.6 contained an error; the results are subsumed and extended by the paper "Hausdorff measure on o-minimal structures" with A. Fornasiero