A note on compromise values

The aim of this note is to provide a unified theory of all compromise values defined as the τ-value in cooperative game theory. The so-called covariance property plays a crucial role in our approach and, related to this property, a family of covariant compromise values is introduced. The mentioned characterization is obtained by means of the covariance, efficiency and certain specific proportionality properties. We also prove that the Shapley value belongs to this family, when one is confined to the class of zero-normalized games.