A minimum spanning set of judgments for a cluster of n elements consists of a set of n-1 judgments, in that every element can be "reached" from every other element. It is necessary to have a spanning set of judgments in order to compute the priorities for the elements within a cluster.
Any judgments beyond the minimum number for a spanning set are called "redundant" because they are not needed to compute priorities. They are necessary, however, to improve the accuracy of the priorities, especially in the case of verbal judgments.
