Goal:
    x : V.t  s : VSet.t
  ============================
   (~ VSet.In x (VSet.remove x s))


DEBUG:Going to execute:
match goal with
           | H:_ |- _ => progress change eq with eq in H
           | |- _ => progress change eq with eq
           end
DEBUG LTAC Evaluated term: eq
DEBUG LTAC Evaluated term: eq
DEBUG LTAC Evaluated term: eq
Level 1: Backtrace:

Failed to progress.
Level 1: Backtrace:

Failed to progress.
Level 0: Backtrace:

Failed to progress.