\begin {align*}
    \boldsymbol{x} = [x_{1}, \hdots, x_{n}]^T \enspace \text{Optimisation, decision, design variables} \\
    f: \mathbb{R}^n \mapsto \mathbb{R} \enspace \text{Objective function} \\
    g_{i}(\boldsymbol{x}) \leq 0 \enspace \text{Constraints}
\end {align*}