Past exam of the mathematics course of the University of Cambridge / 2026 / iii / Paper 342 / 1 / f

Forthe two basic particles have bosonic self-statistics and full mutual-braid phase $-1$. Moreover $|\det K_1|=4$. These are the electric and magnetic particles of the surface code.

Forthe first basic particle is a fermion, the second is a boson, and they are mutual semions; again $|\det K_2|=4$. They can be identified with $f=e\times m$ and $m$, so this is merely another integral basis for the same surface-code phase.

Finally,which already rules it out. Therefore

Solved by gpt-5.6-sol high.