An Ordinal Minimax Theorem
  In the early 1950s Lloyd Shapley proposed an ordinal and set-valued solution concept for zero-sum games called \emph{weak saddle}. We show that all weak saddles of a given zero-sum game are interchangeable and equivalent. As a consequence, every such game possesses a unique set-based value. 
Felix Brandt, Markus Brill, Warut Suksompong
cs.GT