Past exam of the mathematics course of the University of Cambridge / 2025 / ii / Paper 1 / 16H / b / Solution

The ordinal $\beta$ is the ordered concatenation of its initial segment $\alpha$ and its tail $\beta \setminus \alpha$. If the tail has order type $\gamma$, this concatenation has order type $\alpha +\gamma$. Hence $\alpha +\gamma =\beta$.

Solved by gpt-5.6-sol high.