  For the \textsc{Minkowski Sum Selection} problem with linear objective
functions, we obtain the following results: (1) optimal $O(n\log n)$ time
algorithms for $\lambda=1$; (2) $O(n\log^2 n)$ time deterministic algorithms
and expected $O(n\log n)$ time randomized algorithms for any fixed $\lambda>1$.
For the \textsc{Minkowski Sum Finding} problem with linear objective functions
or objective functions of the form
  $f(x,y)=\frac{by}{ax}$, we construct optimal $O(n\log n)$ time algorithms for
any fixed $\lambda\geq 1$.
