Goal:
    A : Type  n : nat  P : A → bool  d : A  H : is_true true  H0 : S n < 0
  ============================
   (∃ x : A, d = x ∧ P x)


DEBUG:Going to execute:
inversion H

Goals:

DEBUG:Going to execute:
try do_atom

Goals:

DEBUG:Going to execute:
try arith_congr

Goals:

DEBUG:Going to execute:
solve [ split; do_ccl ]