Respecting linear orders for supermajority rules

We study the problem of aggregating individual preferences into a collective ranking without ties (a linear order) over a finite set of alternatives. We introduce a framework that constructs such rankings from supermajority rules, defined by a threshold parameter $$\alpha \in \left[ 1/2,1\right) $$ . For each $$\alpha $$ , we consider the binary relation of defeats from pairwise comparisons and apply two closure operations—the transitive closure and the Suzumura-consistent closure—to eliminate cycles. We then study the sets of linear orders that respect these relations; that is, linear orders that preserve all strict defeats while extending them to a complete ranking. To avoid the arbitrariness of fixing a single $$\alpha $$ , we take the intersection across all $$\alpha $$ . This yields two sets of linear orders: the T-order set (from the transitive closure) and the S-order set (from the Suzumura-consistent closure), both always nonempty, the former is a subset of the latter, and jointly capturing the full spectrum of supermajority rules. We show that this perspective unifies prominent methods: the Schulze method coincides with the T-order set, the Split Cycle method with the S-order set, and every outcome of the Ranked Pairs method lies within the S-order set. Moreover, every linear order in the S-order set satisfies the extended Condorcet criterion and the strong Pareto principle. Our results thus place these methods within a common supermajority-based framework and clarify their relationships.

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Publication Details

Journal
Social Choice and Welfare
Published
2026-06-30
DOI
https://doi.org/10.1007/s00355-026-01666-6
Primary Topic
Game Theory and Voting Systems
Type
article
Field-Weighted Citation Impact
0.00

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article

Respecting linear orders for supermajority rules

Yasunori Okumura
Social Choice and Welfare
Game Theory and Voting Systems
article

Respecting linear orders for supermajority rules

Yasunori Okumura
article en

Abstract

We study the problem of aggregating individual preferences into a collective ranking without ties (a linear order) over a finite set of alternatives. We introduce a framework that constructs such rankings from supermajority rules, defined by a threshold parameter $$\alpha \in \left[ 1/2,1\right) $$ . For each $$\alpha $$ , we consider the binary relation of defeats from pairwise comparisons and apply two closure operations—the transitive closure and the Suzumura-consistent closure—to eliminate cycles. We then study the sets of linear orders that respect these relations; that is, linear orders that preserve all strict defeats while extending them to a complete ranking. To avoid the arbitrariness of fixing a single $$\alpha $$ , we take the intersection across all $$\alpha $$ . This yields two sets of linear orders: the T-order set (from the transitive closure) and the S-order set (from the Suzumura-consistent closure), both always nonempty, the former is a subset of the latter, and jointly capturing the full spectrum of supermajority rules. We show that this perspective unifies prominent methods: the Schulze method coincides with the T-order set, the Split Cycle method with the S-order set, and every outcome of the Ranked Pairs method lies within the S-order set. Moreover, every linear order in the S-order set satisfies the extended Condorcet criterion and the strong Pareto principle. Our results thus place these methods within a common supermajority-based framework and clarify their relationships.

Social Choice and Welfare
Tokyo University of Marine Science and Technology (JP)
Kansai University, Japan Society for the Promotion of Science
Openalex Percentile: Top 4%
Game Theory and Voting Systems
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