1. An inference engine method for ranking and highlighting candidates in a map intuition system, comprising: receiving at a processor a source data set having data with input field values, each source data set having a source data set definition describing the data in the source data set; receiving at the processor a target data set having data with output field values Vo, each target data set having a target data set definition describing the data in the target data set; said processor comparing each input field value with each output field value, identifying a degree of correspondence between each pair of values, ranking the source and output field values into clusters, and merging the rankings from a data level to a data definition level; wherein the step of ranking the source and output field values into clusters comprises: identifying, for each output field value Vo, a set No of other output field values within a predetermined distance from Vo; identifying a set S of input items Vs related to No; identifying, for each item Vs in S, a set Ni of other input field values within a second predetermined distance from Vs; ranking at least one of the size, quality of match, and distinctiveness of match of the set Ni compared to No; and determining, based upon a predetermined threshold, whether to increase the value of the degree of correspondence between items in Ni to items in No.