Goal:
  
  A : Type
  B : Type
  C : Type
  P : A → B → C → Type
  c : C
  a : A
  ls2 : list A
  b : B
  ls3 : list B
  X : P a b c
  X2 : All2 (λ (x : A) (y : B), P x y c) ls2 ls3
  ============================
   (All2 (λ (x : A) (y : B), All (P x y) [c]) ls2 ls3)


DEBUG:Going to execute:
solve
[ eauto
| (first [ eapply All2_impl | eapply All2_fold_impl | eapply All_impl ]); tea;
   cbn; intros *; inversion 1 + constructor; subst; eauto ]
Level 0: Backtrace:

In environment
A : Type
B : Type
C : Type
P : A → B → C → Type
c : C
a : A
ls2 : list A
b : B
ls3 : list B
X : P a b c
X2 : All2 (λ (x : A) (y : B), P x y c) ls2 ls3
Unable to unify "All2 ?M3128 (?M3129 :: ?M3131) (?M3130 :: ?M3132)" with
 "All2 (λ (x : A) (y : B), All (P x y) [c]) ls2 ls3".
Level 0: Backtrace:

In environment
A : Type
B : Type
C : Type
P : A → B → C → Type
c : C
a : A
ls2 : list A
b : B
ls3 : list B
X : P a b c
X2 : All2 (λ (x : A) (y : B), P x y c) ls2 ls3
Unable to unify "All2 ?M3128 (?M3129 :: ?M3131) (?M3130 :: ?M3132)" with
 "All2 (λ (x : A) (y : B), All (P x y) [c]) ls2 ls3".
Level 0: Backtrace:

In environment
A : Type
B : Type
C : Type
P : A → B → C → Type
c : C
a : A
ls2 : list A
b : B
ls3 : list B
X : P a b c
X2 : All2 (λ (x : A) (y : B), P x y c) ls2 ls3
Unable to unify "All2 ?M3128 (?M3129 :: ?M3131) (?M3130 :: ?M3132)" with
 "All2 (λ (x : A) (y : B), All (P x y) [c]) ls2 ls3".