DEMO — A Demo of Epistemic Modelling

This paper introduces and documents DEMO, a Dynamic Epistemic Modelling tool. DEMO allows modelling epistemic updates, graphical display of update results, graphical display of action models, formula evaluation in epistemic models, translation of dynamic epistemic formulas to PDL formulas. Also, DEMO implements the reduction of dynamic epistemic logic [22, 2, 3, 1] to PDL given in [17] and presented in the context of generic languages for communication and change in [6]. Epistemic models are minimized under bisimulation, and update action models are simplified under action emulation (an appropriate structural notion for having the same update effect, cf. [19]). The paper is an exemplar of tool building for epistemic update logic. It contains the essential code of an implementation in Haskell [27], in ‘literate programming’ style [28], of DEMO.