Goal:
  
  A : Type
  t' : A
  P : nat → A → A → Type
  i : nat
  hd : A
  tl : list A
  p : P i hd t'
  ============================
   (hd = t')


DEBUG:Going to execute:
<Coq.Init.Tauto.is_empty> flags X1; elim H
Level 3: Backtrace:

In environment
A : Type
t' : A
P : nat → A → A → Type
i : nat
hd : A
tl : list A
p : P i hd t'
Unable to unify "t'" with "hd".
Level 3: Backtrace:

In environment
A : Type
t' : A
P : nat → A → A → Type
i : nat
hd : A
tl : list A
p : P i hd t'
Unable to unify "t'" with "hd".
Level 4: Backtrace:

In environment
A : Type
t' : A
P : nat → A → A → Type
i : nat
hd : A
tl : list A
p : P i hd t'
Unable to unify "t'" with "hd".
Level 4: Backtrace:

In environment
A : Type
t' : A
P : nat → A → A → Type
i : nat
hd : A
tl : list A
p : P i hd t'
Unable to unify "t'" with "hd".
Level 3: Backtrace:

In environment
A : Type
t' : A
P : nat → A → A → Type
i : nat
hd : A
tl : list A
p : P i hd t'
Unable to unify "t'" with "hd".
Level 3: Backtrace:

In environment
A : Type
t' : A
P : nat → A → A → Type
i : nat
hd : A
tl : list A
p : P i hd t'
Unable to unify "t'" with "hd".