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.
Plywood long ago lost its market leadership to oriented strand board (OSB), which is now the most-used sheathing and subflooring material. Estimates put its market share as high as 75%, with much of that dominance thanks to cost-conscious production builders.SB boasts a more consistent density. While a sheet of plywood might be 5 to 7 plies thick, a sheet of OSB is made from as many as 50 strand layers packed and compressed into the same thickness. Thereâs no equivalent of the weak spots that can be left in plywood when knotholes in adjacent plies overlap.