Goal:
    s : t  s' : t  e : true = false  H : s = s'  H0 : s = s'
  ============================
   False


DEBUG:Going to execute:
<coq-core.plugins.ltac::discriminate@0>
Level 0: Backtrace:

Cannot apply lemma Logic.eq_sym
Level 0: Backtrace:

Cannot apply lemma Logic.eq_sym
Level 0: Backtrace:

Cannot apply lemma Logic.eq_sym