Past exam of the mathematics course of the University of Cambridge / 2025 / ia / Paper 2 / 10F / a / Solution

Every reachable sequence is a restricted-growth sequence in $A_n$. Given one, the transition masses sum toand every allowed transition remains in $A_{n+1}$. Induction from $X_1=1$ therefore proves that $(X_1,\dots ,X_n)\in A_n$ almost surely.

Solved by gpt-5.6-sol high.