Linear-time–Branching-time Spectroscope: TACAS 2021 Edition

The “Linear-time–Branching-time Spectroscope” is a web app to find all preorders, equivalences and inequivalences from the (strong) linear-time–branching-time spectrum for small processes.

The artifact contains the tool together with some tests, and a program to generate the distinguishing formulas for interesting processes named in the paper. The tool is also available via https://concurrency-theory.org/ltbt-spectroscope/.

The corresponding TACAS 2021 paper introduces a generalization of the bisimulation game that can be employed to find all relevant distinguishing Hennessy--Milner logic formulas for two compared finite-state processes. Using these, we can give a precise characterization of how much distinguishing power is needed to tell two processes apart—and thus also determine the best fit of equivalences to equate them.

The tool also displays the game on top of the transition system, although it (for now) needs some training to read this visualization.