A metric space $(X, d)$ is called an $M$-space if for every $x$ and $y$ in $X$ and for every $r \in \lbrack 0, \lambda \rbrack$ we have $B\lbrack x, r \rbrack \cap B ...

The nonconvex problem of minimum curvature is considered in detail and sufficient conditions for existence of solutions as well as characterizations are presented. The L ∞ minimization problem of ...