1. A pattern learning system comprising: a pattern learning tool comprising memory storing instructions executable on a computing system, the pattern learning tool operable to: receive a plurality of sequential event messages from one or more sensors; generate a plurality of graphs that each represents a sub-sequence of the plurality of event messages, each graph comprising a trigger event message, a consequence event message, and one or more intermediary event messages; combine the plurality of graphs to form a combined graph according to a type of each event message; and determine a causal sequence from the combined graph according to a heaviest weighted directed path from the trigger event message to the consequence event message.