 Another notion of group knowledge is distributed knowledge (Fagin et al. 1995). Intuitively, a group B of agents has distributed knowledge that F is true if and only if, were they to pool together all that they know, they would then know F. As an example, if agents a and b are going to visit a mutual friend, a knows that the friend is at home or at work, and b knows that the friend is at work or at the cafe, then a and b have distributed knowledge that the friend is at work: after they pool together what they know, they will each know the location of the friend. Distributed knowledge and public announcements have been studied by Wáng and Ågotnes (2011). Related to this is the study of whether a notion of group knowledge (such as distributed knowledge) satisfies the property that something known by the group can be established via communication; see Roelofsen (2007) for details. 