Debreu (American Economic Review 50:186–188, 1960) famously criticized Luce (Individual choice behavior, Wiley, New York, 1959) choice model with what became known as the red-bus blue-bus example: if a choice set contains two distinct alternatives C (car) and B (blue bus) then adding a third alternative A (red bus) that is essentially identical to B does not affect the choice probability of C but reduces the choice probability of B by half. Debreu’s critique highlights the existence of substitution effects violating the principle of independence from irrelevant alternatives—the cornerstone of Luce (Individual choice behavior, Wiley, New York, 1959) choice model. This paper weakens this principle to construct a model of probabilistic choice satisfying Debreu’s critique.

Debreu（《美国经济评论》50:186–188, 1960）著名地批评了 Luce（个人选择行为，Wiley，纽约，1959）选择模型，其后来被称为红巴士蓝巴士示例：如果一个选择集包含两个不同的替代方案C（汽车）和B （蓝色巴士），然后添加与B基本相同的第三个替代方案A （红色巴士）不会影响C的选择概率，但会降低B的选择概率减半。德布鲁的批评强调替代效应的存在违反了独立于不相关替代品的原则——卢斯（个人选择行为，威利，纽约，1959）选择模型的基石。本文削弱了这一原则，构建了一个满足德布鲁批评的概率选择模型。