Disjunction Property and Finite Model Property For an Intuitionistic Epistemic Logic

We show finite model property, disjunction property and decidability for an intuitionistic epistemic logic IEC. Intuitionistic logic is originally a formalisation of a single mathematician whose knowledge increases over time. The logic IEC formalises multiple agents that communicate asynchronously and whose knowledge increases over time. Although soundness and strong completeness for IEC for a Kripke semantics was straightforward, finite model property and disjunction property required a special technique called modal map on sets of formulas.