This is great! I'm so glad someone took the effort to do this. I discovered Logicola as part of ordering and reading his Formal Ethics text book. His books had

This is great! I'm so glad someone took the effort to do this. I discovered Logicola as part of ordering and reading his Formal Ethics text book. His books had a way of making modal logic feel accessible enough for me to learn. I also quite enjoyed Formal Ethics, which was a book devoted to deriving the Golden Rule from first principles, a set of four non-controversial axioms. I had fun working through it and creating my own cheat sheet LaTeX document showing the complete derivation, including the final representation of the "strict" version of the Golden Rule in modal logic notation. I actually put that on our wedding poster when my wife and I got married, and sent a photo of it to Gensler. He got a kick out of that. I remember also asking him if it could be derived with constructive logic rather than by contradiction. He didn't have a fitch proof of that sort but thought it should be possible.