What was one of the main advantages of BPR at Chevron?​

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)?

Simon says is a memory game where "simon" outputs a sequence of 10 characters (r, g, b, y) and the user must repeat the sequence. create a for loop that compares the two strings. for each match, add one point to user_score. upon a mismatch, end the game. sample output with inputs: 'rrgbryybgy' 'rrgbbrybgy'

Description: write function lastfirst() that takes one argument—a list of strings of the format "lastname, firstname" —and returns a list consisting of two lists: (a) a list of all the last names (b) a list of all the first names