Convex vacancy creation costs shape firms’ responses to trade liberalisation. They induce capacity constraints by increasing firms’ costs of production. A profit maximising firm will therefore not fully meet the increased foreign demand, but serve only a few export markets. More productive firms will export to more countries and profit more from trade liberalisation. To get an effect of trade liberalisation on wage inequality, we need on-the-job search and convex vacancy creation costs because with linear costs trade liberalisation affects all wages in equal proportion. Furthermore, with convex vacancy creation costs, not all firms export to all foreign markets even if trade is fully liberalised. This implies that wage inequality under free trade is always higher than under autarky.

中文翻译：

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全球经济中的凸空缺创造成本和在职搜索

凸的空缺创造成本决定了公司对贸易自由化的反应。它们通过增加企业的生产成本来引发产能限制。因此，利润最大化的公司将不能完全满足日益增长的国外需求，而只能服务于少数出口市场。生产力更高的公司将向更多国家出口，并从贸易自由化中获得更多利润。为了获得贸易自由化对工资不平等的影响，我们需要在职搜索和凸的空缺创造成本，因为贸易自由化以线性成本影响所有工资的比例相同。此外，由于空缺创造成本凸，即使贸易完全自由化，也并非所有公司都向所有外国市场出口。这意味着自由贸易下的工资不平等总是高于自给自足下的。