Input-output conformance simulation (iocos) has been proposed by Gregorio-Rodr\'iguez, Llana and Mart\'inez-Torres as a simulation-based behavioural preorder underlying model-based testing. This relation is inspired by Tretman's classic ioco relation, but has better worst-case complexity than ioco and supports stepwise refinement. The goal of this paper is to develop the theory of iocos by studying logical characterisations of this relation and its compositionality. More specifically, this article presents characterisations of iocos in terms of modal logics and compares them with an existing logical characterisation for ioco proposed by Beohar and Mousavi. A precongruence rule format for iocos and a rule format ensuring that operations take quiescence properly into account are also given. Both rule formats are based on the GSOS format by Bloom, Istrail and Meyer.

翻译：输入输出一致性模拟（iocos）由Gregorio-Rodríguez、Llana和Martínez-Torres提出，是一种基于模拟的、支撑模型驱动测试的行为预序关系。该关系受Tretman经典ioco关系启发，但在最坏情况复杂度上优于ioco，并支持逐步精化。本文旨在通过研究该关系的逻辑表征及其组合性来发展iocos理论。具体而言，本文给出了iocos在模态逻辑方面的表征，并与Beohar和Mousavi提出的ioco现有逻辑表征进行了比较。此外，还给出了iocos的预相容规则格式以及确保操作恰当处理静止状态的规则格式。这两种规则格式均基于Bloom、Istrail和Meyer提出的GSOS格式。