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.
The commodity price of OSB in the last 5 years has been a low of $5/sheet to a high of $25/sheet. Currently (6/18/12) OSB is running about $10/sheet for 7/16â³ thick and CDX Plywood 1/2â³ thick is about $17/sheet. A typical 3000 sf house might use 150 sheets for exterior sheathing so this price difference isnât insignificant. It can easily run $1000 more per house to use plywood compared to the less expensive OSB.