Strong Completeness and Limited Canonicity for PDL
Journal of Logic, Language and Information
Journal of Logic, Language and Information
A first-order dynamic probability logic
ECSQARU'13 Proceedings of the 12th European conference on Symbolic and Quantitative Approaches to Reasoning with Uncertainty
Hi-index | 0.00 |
Propositional dynamic logic ( $$\mathsf{PDL}$$ ) is complete but not compact. As a consequence, strong completeness (the property $$\Gamma \models \varphi \Rightarrow \Gamma \vdash \varphi$$ ) requires an infinitary proof system. In this paper, we present a short proof for strong completeness of $$\mathsf{PDL}$$ relative to an infinitary proof system containing the rule from [驴; β n ]驴 for all $$n \in {\mathbb{N}}$$ , conclude $$[\alpha;\beta^*] \varphi$$ . The proof uses a universal canonical model, and it is generalized to other modal logics with infinitary proof rules, such as epistemic knowledge with common knowledge. Also, we show that the universal canonical model of $$\mathsf{PDL}$$ lacks the property of modal harmony, the analogue of the Truth lemma for modal operators.