1. A method for determining a causative event in an information technology infrastructure comprising: collecting historical event data with a computer; generating an undirected graph, each node being an event and each edge being a joint probability of two events historically occurring simultaneously; generating a directed graph, each node being the event and each edge being a conditional probability of a second event occurring if a first event occurs; reducing the undirected graph by discarding edges based on mutual information calculated for each edge; reducing the directed graph by discarding edges that correspond to discarded edges of the undirected graph; and from the directed graph, creating and outputting an historical list of recommendations to a user, the historical list of recommendations comprising an at least one event deemed to be the most likely causative event.