A remarkable result on the ArXiv tonight, due to Kedlaya, Kolpakov, Poonen, and Rubinstein, at https://t.co/YNcWqgZj3M. One of the highlights is that they fully classify tetrahedra (= triangular pyramids) with rational dihedral angles. Here's what they prove… (1/n)

— Marty Weissman (@marty__weissman) December 1, 2020