Goal:
    x : t  y : t  hlt : lt x y  H : False
  ============================
   (Gt = Lt)


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

In environment
x, y : t
hlt : lt x y
H : False
Unable to unify "Lt" with "Gt".
Level 0: Backtrace:

In environment
x, y : t
hlt : lt x y
H : False
Unable to unify "Lt" with "Gt".