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 indica-
tion 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