{X : SSet} →
  {A : X.Subcomplex} →
    {P : A.Pairing} →
      {α : Type v} →
        [inst : PartialOrder α] →
          {motive : P.RankFunction α → Sort u_1} →
            ((rank : ↑P.II → α) →
                (lt : ∀ {x y : ↑P.II}, P.AncestralRel x y → rank x < rank y) → motive { rank := rank, lt := lt }) →
              (t : P.RankFunction α) → motive t