... Four types of galaxy environments are considered: clusters, centers of groups, other places in groups, and the field. ... In order to check whether the mean ages of the stellar populations depend on environment density monotonically, as the hierarchical par­ adigm predicts, in this work I consider four types of environment separately: the cluster galaxies, the brightest (central ) galaxies of groups, the second­ranked group members, and the field galaxies. ... Group center SB(rs)0# 204 637 1996 Oct ...