Undo the last proof step to try something else. Sometimes proof search can get into dead ends if you were trying to prove a formula in a way that did not ultimately succeed. Don't despair, simply undo proof steps and try again.

If you want to undo multiple steps at a time, you can also prune a whole part of the proof.

  1. Expand the proof by clicking a sign
  2. Right-click on the rule name at a rule bar to open its context menu
  3. Select the Prune action