A sparse ruler is called optimal if it is both minimal and maximal. Since the number of distinct pairs of marks is m ( m â 1 ) / 2 {\displaystyle m(m-1)/2} , this is an upper bound on the length L {\displaystyle L} of any maximal sparse ruler with m {\displaystyle m} marks.
1 One 23/32-inch 4x8-foot plywood piece weighs approximately 67 pounds, while a piece of OSB of the same dimensions weighs approximately 78 pounds.
OSB vs. Plywood. While OSB (Oriented Strand Board) is generally cheaper than plywood, it is heavier and not as stiff as plywood and can result in soft squeaky floors under weight. The biggest complaint against OSB is that it doesn't handle moisture very well so it is more suited for indoor use.