From Independence of Clones to Composition Consistency: A Hierarchy of Barriers to Strategic Nomination

Fuente: arXiv
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Auteurs principaux: Berker, Ratip Emin, Casacuberta, Sílvia, Robinson, Isaac, Ong, Christopher, Conitzer, Vincent, Elkind, Edith
Format: Preprint
Publié: 2025
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author Berker, Ratip Emin
Casacuberta, Sílvia
Robinson, Isaac
Ong, Christopher
Conitzer, Vincent
Elkind, Edith
author_facet Berker, Ratip Emin
Casacuberta, Sílvia
Robinson, Isaac
Ong, Christopher
Conitzer, Vincent
Elkind, Edith
contents We study two axioms for social choice functions that capture the impact of similar candidates: independence of clones (IoC) and composition consistency (CC). We clarify the relationship between these axioms by observing that CC is strictly more demanding than IoC, and investigate whether common voting rules that are known to be independent of clones (such as STV, Ranked Pairs, Schulze, and Split Cycle) are composition-consistent. While for most of these rules the answer is negative, we identify a variant of Ranked Pairs that satisfies CC. Further, we show how to efficiently modify any (neutral) social choice function so that it satisfies CC, while maintaining its other desirable properties. Our transformation relies on the hierarchical representation of clone structures via PQ-trees. We extend our analysis to social preference functions. Finally, we interpret IoC and CC as measures of robustness against strategic manipulation by candidates, with IoC corresponding to strategy-proofness and CC corresponding to obvious strategy-proofness.
format Preprint
id arxiv_https___arxiv_org_abs_2502_16973
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle From Independence of Clones to Composition Consistency: A Hierarchy of Barriers to Strategic Nomination
Berker, Ratip Emin
Casacuberta, Sílvia
Robinson, Isaac
Ong, Christopher
Conitzer, Vincent
Elkind, Edith
Computer Science and Game Theory
91B12, 91B14, 68T01, 68Q25
F.2; I.2; J.4
We study two axioms for social choice functions that capture the impact of similar candidates: independence of clones (IoC) and composition consistency (CC). We clarify the relationship between these axioms by observing that CC is strictly more demanding than IoC, and investigate whether common voting rules that are known to be independent of clones (such as STV, Ranked Pairs, Schulze, and Split Cycle) are composition-consistent. While for most of these rules the answer is negative, we identify a variant of Ranked Pairs that satisfies CC. Further, we show how to efficiently modify any (neutral) social choice function so that it satisfies CC, while maintaining its other desirable properties. Our transformation relies on the hierarchical representation of clone structures via PQ-trees. We extend our analysis to social preference functions. Finally, we interpret IoC and CC as measures of robustness against strategic manipulation by candidates, with IoC corresponding to strategy-proofness and CC corresponding to obvious strategy-proofness.
title From Independence of Clones to Composition Consistency: A Hierarchy of Barriers to Strategic Nomination
topic Computer Science and Game Theory
91B12, 91B14, 68T01, 68Q25
F.2; I.2; J.4
url https://arxiv.org/abs/2502.16973