Goal:
  
  A : Type
  P : list A → list A → A → A → Type
  a : A
  Γ : list A
  d' : A
  Γ'0 : list A
  Hrel : All2_fold P Γ Γ'0
  p : P Γ Γ'0 a d'
  ============================
   (Some d' = Some ?d' × All2_fold P Γ Γ'0 × P Γ Γ'0 a ?d')


DEBUG:Going to execute:
F x2 x1 x0
Level 0: Backtrace:

P is used in conclusion.
Level 0: Backtrace:

P is used in conclusion.
Level 0: Backtrace:

P is used in conclusion.
Level 0: Backtrace:

P is used in conclusion.
Level 0: Backtrace:

P is used in conclusion.
Level 1: Backtrace:

P is used in conclusion.
Level 0: Backtrace:

P is used in conclusion.