An optimal mowing plan is sought. A mowing plan designates a starting position and from there gives a complete mowing path. An optimal mowing plan is one closest to a straight line in the sense that the sum of all the changes in the mower's angular direction is minimized, each such change taken as the minimum possible positive value. The mower is not impeded by the border of the square and can travel without difficulty outside it as well as inside it.
Is "spiral" better than "back and forth," and what about a "diagonal" plan?