Before revision:  Finally, we consider the version, where every L-frame intersects a vertical and a horizontal line , and show that this version is linear-time solvable. We also consider these versions of the problem in the so-called "edge intersection model" , and obtain several interesting results.
After revision:  Finally, we consider the version, where every L-frame intersects a vertical and a horizontal line . Finally, we consider the MDS problem in the so-called "edge intersection model" , and obtain several interesting results.