arXiv subjects

Felix Fritz

Publications and source records attributed to Felix Fritz.

3 recordsLinked to original sources

arXiv2026

Lexicographic Social Ranking on Monotonic Coalitional Rankings

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.

cs.GT↗

arXiv2026

An adjacency-based algorithm for computing all extreme-supported non-dominated points of a bi-objective combinatorial optimisation problem

Generally, multi-objective optimisation problems are solved exactly or approximated by solving a series of scalarisations, for example by dichotomic search. In this paper, we take a different approach and attempt to compute the set of all extreme-supported non-dominated points of a bi-objective combinatorial optimisation problem by using a neighbourhood-based approach. Whether or not this works depends on the definition of adjacency and we provide sufficient conditions that guarantee its success. The resulting generic algorithm is an alternative to dichotomic search in our setting. We then apply our generic algorithm to a specific example: the bi-objective minimum weight basis problem, in which we are given a matroid and want to find bases of minimum weight. We use the natural definition of adjacency, in which two bases are adjacent if they differ in exactly one element. Since this satisfies our sufficient condition on the adjacency relation, our generic algorithm works in this case and we analyse its running time, showing that it is polynomial. By tailoring this algorithm specifically to matroids, we obtain one that is faster but no longer transitions between adjacent solutions, instead swapping directly from one extreme-supported point to the next in a combinatorial fashion.

math.OC↗

arXiv2024

Desirability and social rankings

In coalitional games, a player $i$ is regarded as strictly more desirable than player $j$ if substituting $j$ with $i$ within any coalition leads to a strict augmentation in the value of certain coalitions, while preserving the value of the others. We adopt a property-driven approach to 'integrate' the notion of the desirability relation into a total relation by establishing sets of independent axioms leading to the characterization of solutionconcepts from the related literature. We focus on social ranking solutions consistent with the desirability relation and propose complementary sets of properties for the axiomatic characterization of five existing solutions: Ceteris Paribus (CP-)majority, lexicographic excellence (lex-cel), dual-lex, $L^{(1)}$ solution and its dual version $L^{(1)}_{*}$ . These characterizations reveal additional similarities among the five solutions and emphasize the essential characteristics that should be taken into account when selecting a social ranking. A practical scenario involving a bicameral legislature is studied.

cs.GT↗