Goal:
  
  G : t
  HG : acyclic_no_loop
  x : V.t
  y : V.t
  z : V.t
  e : EdgeOf x y
  p : PathOf y z
  IHp : weight p <= sweight (simplify2 p)
  F0 : false = true -> VSet.In x (snodes (simplify2 p))
  H : ~ VSet.In x (snodes (simplify2 p)) -> false = false
  H0 : false = false -> ~ VSet.In x (snodes (simplify2 p))
  ============================
   (e.π1 + weight p <= e.π1 + sweight (simplify2 p))


DEBUG:Going to execute:
<Coq.Init.Tauto.is_unit_or_eq> flags X1; Ltac.cut X2;
            [ intro; clear id
            | Ltac.cut X1; [ exact id | constructor 1; fail ] ]
Level 2: evaluation returns
<coq-core.plugins.tauto::is_unit_or_eq@0>
where
tauto_flags := 
of type
tauto_flags
X1 := ~ VSet.In x (snodes (simplify2 p))
of type
constr of type tacvalue

Level 2: Backtrace:

Tactic failure.
Level 2: Backtrace:

Tactic failure.
Level 1: Backtrace:

Tactic failure.
Level 1: Backtrace:

Tactic failure.
Level 1: Backtrace:

Tactic failure.