We give a definition of bisimulation for conditional modalities interpreted on selection functions and prove the correspondence between bisimilarity and modal equivalence, generalizing the Hennessy–Milner Theorem to a wide class of conditional operators. We further investigate the operators and semantics to which these results apply. First, we show how to derive a solid notion of bisimulation for conditional belief, behaving as desired both on plausibility models and on evidence models. These novel definitions of bisimulations are exploited in a series of (...) undefinability results. Second, we treat relativized common knowledge, underlining how the same results still hold for a different modality in a different semantics. Third, we show the flexibility of the approach by generalizing it to multi-agent systems, encompassing the case of multi-agent plausibility models. (shrink)

The Supreme Court of Canada has established that commercial speech is protected under the Canadian Charter of Rights and Freedoms and that commercial speech exists along a continuum of utility and value, which is balanced against objectives such as public health. This article examines jurisprudence to determine when infringements on commercial speech are acceptable, analyzing considerations of evidence, rational connections between policies and outcomes, proportionality, and minimal impairment.