Goal:
    s : t  s' : t  e : false = true  H : lt s s'
  ============================
   (s = s')


DEBUG:Going to execute:
contradiction
Level 0: Backtrace:

Proof is not complete.
Level 0: Backtrace:

Proof is not complete.
Level 1: Backtrace:

Proof is not complete.
Level 0: Backtrace:

Proof is not complete.
Level 0: Backtrace:

Proof is not complete.