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Logarithmic Approximations for Fair k-Set Selection

2025/05/17 by Shi Li, Chenyang Xu, Li, Shi +3
Business, Management and Accounting · Computer Science · #Complexity and Algorithms in Graphs #Data Structures and Algorithms (cs.DS) #FOS: Computer and information sciences #Facility Location and Emergency Management #Optimization and Search Problems

paper · pdf · doi:10.48550/arxiv.2505.12123

openalex publication_date 2025/05/17 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28

Abstract

We study the fair k-set selection problem where we aim to select k sets from a given set system such that the (weighted) occurrence times that each element appears in these k selected sets are balanced, i.e., the maximum (weighted) occurrence times are minimized. By observing that a set system can be formulated into a bipartite graph G:=(L∪ R, E), our problem is equivalent to selecting k vertices from R such that the maximum total weight of selected neighbors of vertices in L is minimized. The problem arises in a wide range of applications in various fields, such as machine learning, artificial intelligence, and operations research. We first prove that the problem is NP-hard even if the maximum degree Δ of the input bipartite graph is 3, and the problem is in P when Δ=2. We then show that the problem is also in P when the input set system forms a laminar family. Based on intuitive linear programming, we show that a dependent rounding algorithm achieves O((log n)/(log log n))-approximation on general bipartite graphs, and an independent rounding algorithm achieves O(logΔ)-approximation on bipartite graphs with a maximum degree Δ. We demonstrate that our analysis is almost tight by providing a hard instance for this linear programming. Finally, we extend all our algorithms to the weighted case and prove that all approximations are preserved.

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