Reachability in parametric Interval Markov Chains using constraints

Parametric Interval Markov Chains (pIMCs) are a specification formalism that extend Markov Chains (MCs) and Interval Markov Chains (IMCs) by taking into account imprecision in the transition probability values: transitions in pIMCs are labelled with parametric intervals of probabilities. In this work, we study the difference between pIMCs and other Markov Chain abstractions models and investigate three semantics for IMCs: once-and-for-all, interval-Markov-decision-process, and at-every-step. In particular, we prove that all three semantics agree on the maximal/minimal reachability probabilities of a given IMC. We then investigate solutions to several parameter synthesis problems in the context of pIMCs - consistency, qualitative reachability and quantitative reachability - that rely on constraint encodings. Finally, we propose a prototype implementation of our constraint encodings with promising results.