1. A method for automatically localizing failures in a network, comprising: generating an observation from monitoring data associated with network elements in the network; querying a database for a plurality of models of risks; and calculating a hypothesis from said plurality of models of risks that explains said observation, wherein said calculating step comprises applying a greedy approximation to said plurality of models of risks and said observation, wherein said greedy approximation further comprises maximizing a hit ratio and a coverage ratio; wherein said hit ratio is defined as 
 |G i ∩O|/|G i |; wherein said coverage ratio is defined as 
 |G i ∩O|/|O|; and wherein |G i | represents a total number of links that belong to a group G i , |O| represents an input observation and |G i ∩O| represents a number of elements of G i that also belong to O.