Reading Barry Wellman Networks for Newbies I come across this language of networks

Simmel:  Transitivity and Reciprocity in Networks.

In an information network transitivity is , when node A receives the information of node B and node B receives the  information from node C than A has information of node C. Time is a factor here.
Reciprocity is when A receives information of B than B has or will receive information of A.

In social psychology, reciprocity refers to in-kind positive or negative responses of individuals towards the actions of others.

A relation is transitive if whenever an element a is related to an element b, and b is in turn related to an element c, then a is also related to c.

Emergence is the process of complex pattern formation from simpler rules. An emergent behaviour or emergent property can appear when a number of simple entities (agents) operate in an environment, forming more complex behaviours as a collective.

Some sources on this subject on delicious