Construct the boolean logic below using nand gates only and draw its schematic diagram. simplify the expression first. you may use 2-input or 3-input gates. f(x, y, z) = (x + z). (y + z). (x + y + z) a) draw a circuit diagram of an xnor using nand gates only. b) draw a circuit diagram of an xnor using nor gates only.

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)?