1. A computer implemented Minimum Description Length (MDL) based method for constructing a summary of an event sequence S, the method balancing between over-generalizing and over-fitting descriptions of the event sequence S, the method comprising: receiving an event sequence S identifying events of different event types occurring over a time interval; segmenting the event sequence S into segments (S˜,. .. , Sk), wherein k is an integer, wherein the segmenting partitions the time interval into contiguous, non-overlapping intervals, wherein the segmenting minimizing a total cost TL(S,M) in bits for describing the event sequence S, wherein the total cost TL(SgV/) in bits consists of a number of bits used to identify segment boundaries segmenting the event sequence S into segments (S˜,. .. , Sk) and a total local cost LL(Si,Mi) in bits for describing each segment, wherein the total local costs LL(S i ,M˜) in bits consists of a number of bits used to identify a local model M˜ and a number of bits used to describe the corresponding segment S i using the local model Mi, and wherein each local model M˜ groups one or more events of one or more events types within the corresponding segment S i into one or more groups based on a frequency of occurrence of the events; and outputting a summary for the event sequence S, the summary indicating the segments (S˜,. .. , Sk) and the groups; and wherein the time interval is [1,n], and minimizing the total cost TL in bits comprises computing using the following: TL ⁡ ( S , M ) = ∼ log ⁢ ⁢ n + ∑ i = 1 k ⁢ ⁢ LL ⁡ ( Si , M , ) .