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

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

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

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

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

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