Motivation: Consider the solution set \(W\) of the matrix equation \(A\mathbb{x}=\mathbf{0}\text{.}\) This set has a nice property: \(\alpha,\beta\in W\text{,}\)
\(\alpha+\beta\in W\text{.}\)
\(k\alpha\in W\text{.}\)
In this chapter, we would like to understand the following concepts.