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')


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 0: Backtrace:

P is used in hypothesis Hrel.
Level 0: Backtrace:

P is used in hypothesis Hrel.
Level 0: Backtrace:

P is used in hypothesis Hrel.
Level 0: Backtrace:

P is used in hypothesis Hrel.
Level 0: Backtrace:

P is used in hypothesis Hrel.
Level 1: Backtrace:

P is used in hypothesis Hrel.
Level 0: Backtrace:

P is used in hypothesis Hrel.
Level 2: Backtrace:

Not convertible.
Level 2: Backtrace:

Not convertible.
Level 2: Backtrace:

Not convertible.
Level 1: Backtrace:

Not convertible.