For a non-empty, compact set $ A \subseteq \mathbb{R}^n$ , the $ \delta$ -fattening of $ A$ , $ A_\delta$ , is defined to be the set $ $ A_\delta = \cup_{a \in A} B_{\delta}(a), $ $ where $ B_\delta(a)$ denotes the closed ball centered at $ A$ with radius $ \delta$ . Is itRead more