Values and semivalues on subspaces of finite games (Q1117152)

It is proved that every value or semivalue on a linear symmetric subspace of finite games is the restriction to this subspace of a semivalue on the space of all finite games. The theorem is proved for the space of all finite games on a fixed finite set of players, and for the space of all games with a finite support on an infinite set of players (the universe of players).