 Definition 2.2: Suppose that \(f:\mathbb{N}^k \rightarrow \mathbb{N}\) and \(g: \mathbb{N}^{k+2} \rightarrow \mathbb{N}\). Then the term \(\mathcal{PrimRec}_k[f,g]\) denotes the unique function of type \(\mathbb{N}^{k+1} \rightarrow \mathbb{N}\) satisfying (\ref{prscheme}). 