Tournaments on signed graphs

We classify the set of tournament score sequences on signed graphs, generalizing a classical result of Landau. We also study the combinatorics of such tournaments with given score sequence. Specifically, we show that the Coxeter analogues of the interchange graphs introduced by Brualdi and Li remain degree regular. This degree can be interpreted geometrically, in terms of distances in the Coxeter permutahedra studied recently by Ardila, Castillo, Eur and Postnikov.
Comment: v2: minor edits; results unchanged