Goal:
  
  A : Type
  B : Type
  P : B → A → A → Type
  Q : B → A → Type
  b : B
  bs : list B
  hd : A
  tl : list A
  tl' : list A
  X : OnOne2All P bs tl tl'
  X0 : Q b hd
  X1 : All2 Q bs tl
  X2 : OnOne2All (λ (i : B) (x y : A), P i x y × Q i x) bs tl tl'
  ============================
   (OnOne2All (λ (i : B) (x y : A), P i x y × Q i x) bs tl tl')


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.