{"type":"ScholarlyArticle","title":"Phragmén Rules for Degressive and Regressive Proportionality","authors":[{"name":"Michał Jaworski","slug":"micha-jaworski","given":"Michał","family":"Jaworski","affiliation":"University of Warsaw , Poland"},{"name":"Piotr Skowron","slug":"piotr-skowron","given":"Piotr","family":"Skowron","affiliation":"University of Warsaw , Poland"}],"abstract":"We study two concepts of proportionality in the model of approval-based committee elections. In degressive proportionality small minorities of voters are favored in comparison with the standard linear proportionality. Regressive proportionality, on the other hand, requires that larger subdivisions of voters are privileged. We introduce a new family of rules that broadly generalize Phragmén's Sequential Rule spanning the spectrum between degressive and regressive proportionality. We analyze and compare the two principles of proportionality assuming the voters and the candidates can be represented as points in an Euclidean issue space.","doi":"10.24963/ijcai.2022/47","url":"https://ijcai.org/proceedings/2022/47","pdf":"https://ijcai.org/proceedings/2022/0047.pdf","markdown":"https://ijcai.org/proceedings/2022/47.md","bibtex":"https://ijcai.org/proceedings/2022/bibtex/47","volume":{"slug":"2022","title":"Proceedings of the Thirty-First International Joint Conference on Artificial Intelligence","short_title":"IJCAI 2022","url":"https://ijcai.org/proceedings/2022/","year":2022,"location":"Vienna","dates":"23-29 July 2022","editors":"Luc De Raedt","isbn":"978-1-956792-00-3","publisher":"International Joint Conferences on Artificial Intelligence Organization","doi_prefix":"10.24963/ijcai.2022"},"section":"Agent-based and Multi-agent Systems","track":"Main Track","number":47,"pages":{"first":328,"last":334},"keywords":["Agent-based and Multi-agent Systems: Computational Social Choice"],"videos":[{"label":"Video #1","url":"https://slideslive.com/38986610","length_sec":78,"provider":"slideslive"},{"label":"Video #2","url":"https://slideslive.com/38984753","length_sec":352,"provider":"slideslive"}],"references":[{"position":1,"raw":"[Aziz et al., 2017] H. 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