3-3 Ordering by asymptotic growth rates

a. Rank the following functions by order of growth; that is, find an arrangement \(g_1, g_2, \ldots , g_{30}\) of the functions \(g_1 = \Omega(g_2), g_2 = \Omega(g_3), \ldots, g_{29} = \Omega(g_{30})\). Partition your list into equivalence classes such that functions \(f(n)\) and \(g(n)\) are in the same class if and only if \(f(n) = \Theta(g(n))\).

\[ \begin{array}{cccccc} \lg(\lg^{^\*}n) \quad & \quad 2^{\lg^\*n} \quad & \quad (\sqrt 2)^{\lg n} \quad & \quad n^2 \quad & \quad n! \quad & \quad (\lg n)! \\\\ (\frac{3}{2})^n \quad & \quad n^3 \quad & \quad \lg^2 n \quad & \quad \lg(n!) \quad & \quad 2^{2^n} \quad & \quad n^{1/\lg n} \\\\ \lg\lg n \quad & \quad \lg^\* n \quad & \quad n\cdot 2^n \quad & \quad n^{\lg\lg n} \quad & \quad \lg n \quad & \quad 1 \\\\ 2^{\lg n} \quad & \quad (\lg n)^{\lg n} \quad & \quad e^n \quad & \quad 4^{\lg n} \quad & \quad (n + 1)! \quad & \quad \sqrt{\lg n} \\\\ \lg^\*(\lg n) \quad & \quad 2^{\sqrt{2\lg n}} \quad & \quad n \quad & \quad 2^n \quad & \quad n\lg n \quad & \quad 2^{2^{n + 1}} \end{array} \]

b. Give an example of a single nonnegative function \(f(n)\) such that for all functions \(g_i(n)\) in part (a), \(f(n)\) is neither \(O(g_i(n))\) nor \(\Omega(g_i(n))\).

\[ \begin{array}{ll} 2^{2^{n + 1}} & \\\\ 2^{2^n} & \\\\ (n + 1)! & \\\\ n! & \\\\ e^n & \\\\ n\cdot 2^n & \\\\ 2^n & \\\\ (3 / 2)^n & \\\\ (\lg n)^{\lg n} = n^{\lg\lg n} & \\\\ (\lg n)! & \\\\ n^3 & \\\\ n^2 = 4^{\lg n} & \\\\ n\lg n \text{ and } \lg(n!) & \\\\ n = 2^{\lg n} & \\\\ (\sqrt 2)^{\lg n}(= \sqrt n) & \\\\ 2^{\sqrt{2\lg n}} & \\\\ \lg^2 n & \\\\ \ln n & \\\\ \sqrt{\lg n} & \\\\ \ln\ln n & \\\\ 2^{\lg^\*n} & \\\\ \lg^\*n \text{ and } \lg^\*(\lg n) & \\\\ \lg(\lg^\*n) & \\\\ n^{1 / \lg n}(= 2) \text{ and } 1 & \end{array} \]

b. For example,

\[ f(n) = \begin{cases} 2^{2^{n + 2}} & \text{if $n$ is even}, \\\\ 0 & \text{if $n$ is odd}. \end{cases} \]

for all functions \(g_i(n)\) in part (a), \(f(n)\) is neither \(O(g_i(n))\) nor \(\Omega(g_i(n))\).