3.1-4 Is 2n+1 = 0 (21)? Is 22n = 0 (2") ? 3.1-6 Prove that the running time of an algorithm is o (g(n)) if and only if its worst-case running time is O (g(n)) and its best-case running time is 12 (g(n)). 3.1-7 Prove that o (g(n)) nw (g(n)) is the empty set