fact: Definition series_order {α} {R : ring α} {K : field R} : power_series α → nat → Nbar := λ (s : power_series α) (n : nat), match field_LPO (λ j, s.[n+j]) with | inl _ => ∞ | inr (exist _ i _) => fin i end.
imports: Utf8 QArith NPeano Misc NbarM Field2 Power_series