👉 In mathematics, an "expansive" function is a function that increases (or decreases) as its argument approaches a certain point. If you have a function \(f(x)\), and you want to ensure it behaves like a function on the interval \([a,b]\), then \(f\) must be expansive. This means that for all points \(x_0 \in [a, b]\), there exists an \(x\in[a, b]\) such that \(f(x
