Derandomization, explicit construction

Derandomization

Design algorithm which uses random choices; Replace random choice with choice which maximizes conditional expectation; Eg: find $\ge \frac{|E|}{2}$ cut in G=(V, E). Devise rand alg which uses n 2-wise ind bits; enumerate all values for $\log n$ truly ind bits, make n 2-wise ind bits and run rand alg.

Explicit construction algorithms

Sample values for some variables, show that desired object still exists, use exhaustive search for other variables.

Sampling uniformly from unit sphere

Pick each point according to $N(0,n^{-1})$. \why