where (.) denotes a non-decreasing permutation of the inputs such that (x(1) ≤ x(2) ≤
• • • ≤ x(n)) (the same as with the Choquet integral), and Hj = {( j), . . . , (n)}.
Certain indices have been introduced in order to better understand the behavior of
the Choquet and Sugeno integrals. In particular, the Shapley value gives an indication of the overall importance of a given input, while the interaction index between
two inputs shows to what extent they are redundant or complimentary.
Definition 22.10 (Shapley value).
Let v be a fuzzy measure. The Shapley index for every i ∈ N is