Goal:
    x : VSet.elt  p : VSet.t
  ============================
   (VSet.Equal (VSet.add x (VSet.add x p)) (VSet.add x p))


DEBUG:Going to execute:
VSetDecide.MSetDecideAuxiliary.abstract_term t
Level 1: Backtrace:

Tactic failure: no need to abstract a variable.
Level 2: Backtrace:

Tactic failure: no need to abstract a variable.
Level 2: Backtrace:

Tactic failure: no need to abstract a variable.
Level 1: Backtrace:

Tactic failure: no need to abstract a variable.
Level 2: Backtrace:

Tactic failure: no need to abstract a variable.
Level 2: Backtrace:

Tactic failure: no need to abstract a variable.
Level 1: Backtrace:

Tactic failure: no need to abstract a variable.