Stability, Fairness and the Pursuit of Happiness in Recommender Systems

37 Pages Posted: 19 Oct 2022 Last revised: 6 Sep 2023

See all articles by Gerdus Benade

Gerdus Benade

Boston University - Questrom School of Business

Nachiketa Sahoo

Boston University - Questrom School of Business

Date Written: August 10, 2023

Abstract

Top-k personalized recommendations are ubiquitous, but do they make stable matches? We study whether, given complete information, buyers and sellers would participate in matches formed by top-k recommendations instead of pursuing alternative matches among themselves. When there are no constraints on the number of times an item is recommended, we observe that top-k recommendations are stable. When exposures are constrained, e.g., due to limited inventory or exposure opportunities, stable recommendations need not exist. We show that maximizing total buyer welfare is closely related to stability. Maximizing welfare under unit exposure constraints is stable, Pareto optimal and swap-envy free for orthogonal buyers, identical buyers, and buyers with dichotomous valuations. Most of these properties remain under arbitrary exposure constraints. Finally, we evaluate variants of common strategies for recommending under exposure constraint and find that they leave room for substantial instability and envy in three real-world datasets. Among the compared strategies, maximizing buyer welfare leads to the most stable outcomes and near-zero swap-envy.

Keywords: Recommender systems, Stable matching, Fairness, Envy free, Choice models

JEL Classification: C78

Suggested Citation

Benade, Gerdus and Sahoo, Nachiketa, Stability, Fairness and the Pursuit of Happiness in Recommender Systems (August 10, 2023). Boston University Questrom School of Business Research Paper No. 4241170, Available at SSRN: https://ssrn.com/abstract=4241170 or http://dx.doi.org/10.2139/ssrn.4241170

Gerdus Benade

Boston University - Questrom School of Business ( email )

595 Commonwealth Avenue
Boston, MA MA 02215
United States

Nachiketa Sahoo (Contact Author)

Boston University - Questrom School of Business ( email )

595 Commonwealth Avenue
Boston, MA MA 02215
United States

HOME PAGE: http://people.bu.edu/nachi/

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