Algorithmic monoculture arises when many decision-makers rely on the same algorithm to evaluate applicants. An emerging body of work investigates possible harms of this kind of homogeneity, but has been limited by the challenge of incorporating market effects in which the preferences and behavior of many applicants and decision-makers jointly interact to determine outcomes. Addressing this challenge, we introduce a tractable theoretical model of algorithmic monoculture in a two-sided matching market with many participants. We use the model to analyze outcomes under monoculture (when decision-makers all evaluate applicants using a common algorithm) and under polyculture (when decision-makers evaluate applicants independently). All else equal, monoculture (1) selects less-preferred applicants when noise is well-behaved, (2) matches more applicants to their top choice, though individual applicants may be worse off depending on their value to decision-makers and risk tolerance, and (3) is more robust to disparities in the number of applications submitted.

翻译：算法单一种植现象是指众多决策者依赖同一算法来评估申请者时所产生的结果。新兴的研究领域探讨了这种同质化可能带来的危害，但受限于难以将市场效应纳入考量——即众多申请者与决策者的偏好及行为相互作用并共同决定最终结果。为应对这一挑战，我们提出了一种易于处理的理论模型，用于分析存在众多参与者的双边匹配市场中的算法单一种植现象。利用该模型，我们分别分析了单一种植（所有决策者均使用统一算法评估申请者）与混合种植（决策者独立评估申请者）下的结果。在其他条件相同的情况下，单一种植会导致：（1）当噪声表现良好时，会选中更不受欢迎的申请者；（2）更多申请者被匹配到其首选，但个别申请者可能因自身对决策者的价值及风险承受能力而处境更差；（3）对申请提交数量差异的鲁棒性更强。