This is the Proof Machine in sandbox mode, with no fixed fields and one can enter lines as premises. For an example problem in fixed mode, go here. Proof Machine (Sandbox Mode 2.0, BOOL and PROP) 1. 2. 3. 4. 5. 6. Messages Check out the video below for an explanation of the Proof Machine. Feedback Welcome! https://youtu.be/QOfF9Xp2UEE