Given the task definition and input, reply with output. In this task, you're given a pair of sentences, sentence 1 and sentence 2. Your job is to write a single word that describes the genre that the two sentences belong to, such as face-to-face, government, letters, 9/11, slate, telephone, travel, verbatim, oup, fiction.

Sentence 1: The sensitivity of cost to volume for a postal system can be investigated directly provided the ratio of fixed to variable costs is known by function. Sentence 2: Postal system costs are linked to volume.
government