Surreal substructures
Vincent Bagayoko, Joris van der Hoeven · Fundamenta Mathematicae · 2024
Conway’s field $\mathbf{No}$ of surreal numbers comes both with a natural total order and an additional “simplicity relation” which is also a partial order. Considering $\mathbf{No}$ as a doubly ordered structure for these two orderings, an isomorphic cop