Past exam of the mathematics course of the University of Cambridge / 2025 / iii / Paper 114 / 3 / b

There is a natural descriptionClosed balls form a cofinal family of compact subsets of ${\mathbb{R}}^n$. Excision and radial deformation identify every sufficiently large-ball term, and the resulting stable group is the local group at the origin:It is $\mathbb{Z}$ in degree $n$ and zero otherwise.

Solved by gpt-5.6-sol high.