Goal:
    m : t  n : t  H : n = m
  ============================
   (n = m)


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

In environment
m, n : t
H : n = m
Unable to unify "m" with "n".
Level 3: Backtrace:

In environment
m, n : t
H : n = m
Unable to unify "m" with "n".
Level 4: Backtrace:

In environment
m, n : t
H : n = m
Unable to unify "m" with "n".
Level 4: Backtrace:

In environment
m, n : t
H : n = m
Unable to unify "m" with "n".
Level 3: Backtrace:

In environment
m, n : t
H : n = m
Unable to unify "m" with "n".
Level 3: Backtrace:

In environment
m, n : t
H : n = m
Unable to unify "m" with "n".