Goal:
  
  A : Type
  P : list A → list A → A → A → Type
  d : A
  Γ : list A
  X : All_fold (λ (Γ : list A) (d : A), P Γ Γ d d) Γ
  p : P Γ Γ d d
  IHX : All2_fold P Γ Γ
  ============================
   (P Γ Γ d d)


DEBUG:Going to execute:
<Coq.Init.Tauto.is_conj> flags X1; elim id; do 2 intro; clear id
Level 2: evaluation returns
<coq-core.plugins.tauto::is_conj@0>
where
tauto_flags := 
of type
tauto_flags
X1 := Type
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.
Level 1: Backtrace:

Tactic failure.