Collaboration has been defined as cooperation between elements of the population of a defeated state and representatives of a victorious power.[2] Stanley Hoffmann subdivided collaboration into involuntary (reluctant recognition of necessity) and voluntary (exploitation of necessity).[3] According to Hoffmann, collaborationism can be subdivided into "servile" and "ideological"; the former is deliberate service to an enemy, whereas the latter is deliberate advocacy of cooperation with a foreign force which is seen as a champion of desirable domestic transformations.[3] In contrast, Bertram Gordon uses the terms "collaborator" and "collaborationist", respectively, in reference to non-ideological and ideological collaborations.[4]