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


DEBUG:Going to execute:
match goal with
           | H:context [ ?P -> False ] |- _ => fold (~ P) in H
           | |- context [ ?P -> False ] => fold (~ P)
           end
Level 0: Backtrace:

No matching clauses for match.

Goals:
    x : V.t  s : VSet.t  y : VSet.elt
  ============================
   ((VSet.In y (VSet.add x s) -> x = y \/ VSet.In y (VSet.remove x s)) /\
    (x = y \/ VSet.In y (VSet.remove x s) -> VSet.In y (VSet.add x s)))

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


DEBUG:Going to execute:
intros
Level 0: Backtrace:

No matching clauses for match.

Goals:
    x : V.t  s : VSet.t  y : VSet.elt
  ============================
   ((VSet.In y (VSet.add x s) -> x = y \/ VSet.In y (VSet.remove x s)) /\
    (x = y \/ VSet.In y (VSet.remove x s) -> VSet.In y (VSet.add x s)))

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


DEBUG:Going to execute:
VSetDecide.MSetDecideAuxiliary.abstract_elements

Goals:
    x : V.t  s : VSet.t  y : VSet.elt
  ============================
   ((VSet.In y (VSet.add x s) -> x = y \/ VSet.In y (VSet.remove x s)) /\
    (x = y \/ VSet.In y (VSet.remove x s) -> VSet.In y (VSet.add x s)))

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


DEBUG:Going to execute:
repeat
            match goal with
            | |- context [ VSet.singleton ?t ] =>
                  VSetDecide.MSetDecideAuxiliary.abstract_term t
            | _:context [ VSet.singleton ?t ]
              |- _ => VSetDecide.MSetDecideAuxiliary.abstract_term t
            | |- context [ VSet.add ?t _ ] =>
                  VSetDecide.MSetDecideAuxiliary.abstract_term t
            | _:context [ VSet.add ?t _ ]
              |- _ => VSetDecide.MSetDecideAuxiliary.abstract_term t
            | |- context [ VSet.remove ?t _ ] =>
                  VSetDecide.MSetDecideAuxiliary.abstract_term t
            | _:context [ VSet.remove ?t _ ]
              |- _ => VSetDecide.MSetDecideAuxiliary.abstract_term t
            | |- context [ VSet.In ?t _ ] =>
                  VSetDecide.MSetDecideAuxiliary.abstract_term t
            | _:context [ VSet.In ?t _ ]
              |- _ => VSetDecide.MSetDecideAuxiliary.abstract_term t
            end