A Sequence Online Analytical Processing (S-Olap) System 50 For Analysing An Event Database (41) Storing Events (12), The System (50) Comprising: An S-Olap Engine (53) To Compute An S-Cuboid (49) For A Query On The Event Database (41); A Sequence Query Engine (54) To Form Part Of The S-Cuboid (49) By Performing The Steps Of: Selection, Clustering, Sequence Formation And Sequence Grouping; A Cuboid Repository (52) To Store Computed S-Cuboids (49) And To Be Searched By The S-Olap Engine (53) For An S-Cuboid Query To Determine Whether An S-Cuboid Has Previously Been Computed; And A Sequence Cache (56) To Cache Constructed Sequence Groups.

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