61
[0R8] Given a metric space \((M,d)\), given \(Aβ M\) non-empty, we define the distance function \(d_ A:Mβ β\) as
\begin{equation} d_ A(x)=\inf _{yβ A} d(x,y)~ .\label{eq:funz_ distanza} \end{equation}
62
[0R8] Given a metric space \((M,d)\), given \(Aβ M\) non-empty, we define the distance function \(d_ A:Mβ β\) as