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
  H1 : VSet.In x (snodes (simplify2 p)) -> False
  ============================
   (e.π1 + weight p <= e.π1 + sweight (simplify2 p))


DEBUG:Going to execute:
assert X2
Level 1: evaluation returns
assert X2; [ exact (id0 id1) | clear id0 ]
where
id1 := H1
of type
intropattern
id0 := H
of type
intropattern
flags := 
of type
tauto_flags
X2 := false = false
of type
constr of type tacvalue