• Fairness/diversity (of supplier) Very few sets have both high relevance & high fairness of exposure • Conjecture: optimizing for relevance might hurt fairness Mehrotra, McInerney, Bouchard, Lalmas, Diaz. Towards a Fair Marketplace: Counterfactual Evaluation of the trade-off between Relevance, Fairness & Satisfaction in Recommendation Systems. CIKM 2018.