Goal:
  
  A : Type
  P : list A → A → Type
  Q : list A → list A → A → A → Type
  d : A
  d' : A
  Γ : list A
  Γ' : list A
  X : All2_fold (λ (Γ Γ' : list A) (d d' : A), P Γ d × Q Γ Γ' d d') Γ Γ'
  a : P Γ d
  b : Q Γ Γ' d d'
  a0 : All_fold P Γ
  b0 : All2_fold Q Γ Γ'
  ============================
   (All2_fold Q Γ Γ')


DEBUG:Going to execute:
<Coq.Init.Tauto.is_conj> flags X1; Ltac.split
Level 2: evaluation returns
<coq-core.plugins.tauto::flatten_contravariant_disj@0>
where
tauto_flags := 
of type
tauto_flags
id := Q
of type
constr
X2 := list A → A → A → Type
of type
constr
X1 := list A
of type
constr of type tacvalue

Level 2: Backtrace:

Tactic failure.
Level 2: Backtrace:

Tactic failure.
Level 1: Backtrace:

Tactic failure.