Goal:
    A : Type  B : Type  x : A  proj : A → B  size : B → nat  H : False
  ============================
   (size (proj x) < 0)


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

Cannot apply lemma eq_sym
Level 0: Backtrace:

Cannot apply lemma eq_sym
Level 0: Backtrace:

Cannot apply lemma eq_sym