Geometric intuition is going to be difficult, but I bet there's a relatively elegant algebraic argument that uses some index-twiddling symmetries. There's a one

Geometric intuition is going to be difficult, but I bet there's a relatively elegant algebraic argument that uses some index-twiddling symmetries. There's a one-page inductive proof (with four pages of introduction) on arXiv: https://arxiv.org/pdf/1607.05352.pdf https://arxiv.org/pdf/1607.05352.pdf