Past exam of the mathematics course of the University of Cambridge / 2026 / ii / Paper 1 / 4J / a / Solution

The basic functions are zero $Z(\mathbf{x})=0$, successor $S(n)=n+1$, and projections $P_i^k(\mathbf{x})=x_i$. Close these under composition and primitive recursion:

Solved by gpt-5.6-sol high.