Lexicographic Social Ranking on Monotonic Coalitional Rankings

Abstract

Recent studies on social rankings in coalitional settings have introduced methods that rank individuals by lexicographically comparing vectors of their occurrences across coalitions ordered according to their strength. In this work, we focus on two such solutions: the lexicographical excellence (lex-cel) solution, which disregards coalition size, and the L^(1) solution, which additionally prioritizes smaller coalitions through a double lexicographic comparison. We investigate the combinatorial connections between these two solutions on monotonic coalitional rankings, where equivalence classes are compactly represented through sets of minimal (with respect to set inclusion) coalitions. After introducing general formulas for computing the lex-cel and L^(1) parameter vectors from these minimal coalitions, we also present worst-case running time results. Finally, to further explore the behavior of the two solutions through simulations designed to assess the distance of the rankings they produce, we show that the monotonicity assumption does not lead to actual redundancy in the rankings produced by the two solutions.