Abstract

In the previous chapter, we have formulated the problem of sparse representation as optimization problems with ℓ¹ norm, for which there are efficient and fast algorithms. The idea was to approximate the non-convex and discontinuous ℓ⁰ norm by the convex ℓ¹ norm. In this chapter, we consider alternative algorithms that directly solve the ℓ⁰-norm optimization by using the greedy method.