A Blackwell-monotone information cost function assigns higher costs to Blackwell more informative experiments. This paper provides simple necessary and sufficient conditions for Blackwell monotonicity over finite experiments. The key condition is a system of linear differential inequalities that are convenient to check given an arbitrary cost function. When the cost function is additively separable across signals, our characterization implies that Blackwell monotonicity is equivalent to sublinearity. This identifies a wide range of practical information cost functions. Finally, we apply our results to bargaining and persuasion problems with costly information.

翻译：本文提出布莱克威尔单调信息成本函数，该函数赋予布莱克威尔意义上信息量更大的实验以更高的成本。本文给出了有限实验中布莱克威尔单调性的简洁充要条件，其核心条件是一组便于检验任意成本函数的线性微分不等式。当成本函数在信号间满足可加分离性时，我们的刻画表明布莱克威尔单调性等价于次线性性，由此识别出一类广泛的实用信息成本函数。最后，我们将研究成果应用于存在信息成本的讨价还价与说服问题分析。