A set of samples of sensor data is accessed (110) to generate a set of samples (114) recording measurements taken by one or more sensors. Each sample is represented as a minterm (118) to yield a set of minterms. A characteristic function is generated (122) from the set of minterms. The characteristic function, which is preferably generated by applying a logical OR operation to the minterms of the set, indicates whether a given minterm is a member of the set of minterms. Each sample preferably comprises a cheap all of one or more sense of values, 8% of value recording one or more measurements taken by one or more sensors relating to parameters including time, temperature or location.
