Tournaments and Orders with the Pigeonhole Property
Anthony Bonato, Peter J. Cameron, Dejan Delić · Canadian Mathematical Bulletin · 2000
Abstract A binary structure S has the pigeonhole property (𝒫) if every finite partition of S induces a block isomorphic to S. We classify all countable tournaments with (𝒫); the class of orders with (𝒫) is completely classified.