Sub- and superadditive integral means

The integral means are special Cauchy means (see, e.g., [L. Losonczi, On the comparison of Cauchy mean values, J. Inequal. Appl. 7 (2002) 11-24]) depending on one function. The two variable integral means were (independently) defined and studied by Elezović and Pečarić [Differential and integral f-means and applications to digamma function, Math. Inequal. Appl. 3 (2000) 189-196]. The comparison problem of two integral means (under differentiability conditions) was solved by Losonczi [Comparison and subhomogeneity of integral means, Math. Inequal. Appl. 5 (2000) 609-618]. Here we completely characterize the additive, sub- and superadditive integral means of n⩾2 variables.