Goal:
    x : V.t  y : V.t  p : VSet.t  a : V.t
  ============================
   (VSet.In a (VSet.add x (VSet.add y p)) <->
    VSet.In a (VSet.add y (VSet.add x p)))


DEBUG:Going to execute:
VSetDecide.MSetDecideAuxiliary.E_eq_to_Logic_eq
DEBUG LTAC Evaluated term: V.t
DEBUG LTAC Evaluated term: V.t
Level 1: Backtrace:

Failed to progress.
Level 1: Backtrace:

Failed to progress.
Level 1: Backtrace:

Failed to progress.
Level 0: Backtrace:

No matching clauses for match.