Oriented cobordism classes Ω^SO_* forms graded ring under disjoint union. Thom: Ω^SO_n = π_n(MSO). Exotic spheres via Kervaire-Milnor.
Oriented cobordism classes Ω^SO_* forms graded ring under disjoint union. Thom: Ω^SO_n = π_n(MSO). Exotic spheres via Kervaire-Milnor.