A graphical semantic calculator for modal propositional logic, built using D3, MathJax, and Bootstrap.

See it in action at rkirsling.github.io/modallogic!

• The core part of the code is MPL.js, a library for parsing and evaluating well-formed formulas of modal propositional logic. See the API Reference here.
• I've also extracted the directed graph editing code so that it can be easily repurposed. You can find it here.