Goal:
    x : t  H : False
  ============================
   (Lt = Eq)


DEBUG:Going to execute:
Ltac.symmetry; trivial
Level 1: Backtrace:

In environment
x : t
H : False
Unable to unify "Eq" with "Lt".
Level 0: Backtrace:

In environment
x : t
H : False
Unable to unify "Eq" with "Lt".