The photographer john sexton says, “when i'm about ready to press the cable release on the view camera, i've tried to anticipate some of the challenges i'm going to encounter in the darkroom.” how can thinking about the darkroom process or the “digital darkroom” you to take better photographs? what are some aspects that you should think about when taking a photograph?

Suppose there is a relation r(a, b, c) with a b+-tree index with search keys (a, b).1. what is the worst-case cost of finding records satisfying 10 < a < 50 using this index, in terms of the number of records n1, retrieved and the height h of the tree? 2. what is the worst-case cost of finding records satisfying 10 < a < 50 and 5 < b < 10 using this index, in terms of the number of records n2 that satisfy this selection, as well as n1 and h defined above? 3. under what conditions on n1 and n2, would the index be an efficient way of finding records satisfying the condition from part (2)?