Goal:
  
  A : Type
  B : Type
  R : nat → A → B → Type
  n : nat
  x : A
  y : B
  l : list A
  r : list B
  r0 : R n x y
  a : All2i R (S n) l r
  ============================
   (eq_refl = eq_refl)


DEBUG:Going to execute:
<coq-core.plugins.ltac::autounfold@0> $1 $2

Goals:
    A : Type  B : Type  R : nat → A → B → Type  n : nat
  ============================
   (eq_refl = eq_refl)

  
  A : Type
  B : Type
  R : nat → A → B → Type
  n : nat
  x : A
  y : B
  l : list A
  r : list B
  r0 : R n x y
  a : All2i R (S n) l r
  ============================
   (eq_refl = eq_refl)


DEBUG:Going to execute:
constructor
Level 1: Backtrace:

Failed to progress.
Level 1: Backtrace:

Failed to progress.
Level 1: Backtrace:

Failed to progress.
Level 1: Backtrace:

Failed to progress.
Level 1: Backtrace:

Failed to progress.
Level 1: Backtrace:

Failed to progress.

Goals:
    A : Type  B : Type  R : nat → A → B → Type  n : nat
  ============================
   (eq_refl = eq_refl)

  
  A : Type
  B : Type
  R : nat → A → B → Type
  n : nat
  x : A
  y : B
  l : list A
  r : list B
  r0 : R n x y
  a : All2i R (S n) l r
  ============================
   (eq_refl = eq_refl)


DEBUG:Going to execute:
<coq-core.plugins.ltac::constructor@0>