Fixpoint Qhomographic_sign (a b c d : Z) (p : Qpositive) {struct p} :
  forall (H_Qhomographic_sg_denom_nonzero : Qhomographic_sg_denom_nonzero c d p),
  Z * (Z * (Z * (Z * Z)) * Qpositive).Scheme Qhomographic_sg_denom_nonzero_inv_dep :=
  Induction for Qhomographic_sg_denom_nonzero Sort Prop.

Lemma Qhomographic_sign_dL_10 : forall (a b c d : Z) (p xs : Qpositive) (H_Qhomographic_sg_denom_nonzero : Qhomographic_sg_denom_nonzero (c + d) d xs) (H_Qhomographic_sg_denom_nonzero_dL : Qhomographic_sg_denom_nonzero c d (dL xs)), b <> 0%Z -> d <> 0%Z -> ~ inside_interval_1 (outside_interval a b) (outside_interval c d) -> ~ inside_interval_2 (outside_interval a b) (outside_interval c d) -> Qhomographic_sign a b c d (dL xs) H_Qhomographic_sg_denom_nonzero_dL = Qhomographic_sign (a + b) b (c + d) d xs H_Qhomographic_sg_denom_nonzero.