group

A group is a set of actors who form a neighborhood in networks, who perceive that their actions impinge on the state of each other, and who have common >knowledge about the criteria of membership to that group.

Groups where members delegate decisions to a particular actor are in an intermediate stage to the emergence of >organization.

Groups constitute a unit of selection, if their structure is reproduced in time partly independent from the choices of actors, as for example, in the case of traditional rules which are imposed on single actors by collective sanctions such that the group identity is partially autonomous from the actors. In this case, >group selection interacts with individual selection.

Groups are an important unit in EE, because many ideal-typical configurations refer to groups, especially in >game theory.

Basic References
My use of the "group" concept follows
James Grier Miller, Living Systems, New York: McGraw-Hill, 1978.

Semantic Field
actor
group   organization
game   group selection