16. The system of claim 13 , wherein the decay function is configured to determine weights for relational events based on social time.
16. The system of claim 13 , wherein the decay function is configured to determine weights for relational events based on social time. 18. The system of claim 16 , wherein the decay function is configured to determine weights for the one or more relational events contained in the selected subset of relational events by determining a weight for a first relational event based on a number of relational events in the selected subset that involved the actor and that occurred between the first relational event and a second relational event.