proposition: Proposition v_sq_isotoid_idtoiso_2_1 {B : verity_double_bicat} (H : vertically_saturated B) (HB_2_1 : ver_locally_univalent B) {x y : B} {v₁ v₂ : x -|-> y} (p : v₁ = v₂) : v_sq_isotoid_2_1 H HB_2_1 (v_sq_idtoiso_2_1 p) = p.
proof: Proof. unfold v_sq_idtoiso_2_1, v_sq_isotoid_2_1. etrans. { apply maponpaths. exact (homotweqinvweq (vertical_square_weq_invertible_2cell H v₁ v₂) (idtoiso_2_1 v₁ v₂ p)). } apply isotoid_2_1_idtoiso_2_1. Qed.
imports: UniMath.MoreFoundations.All UniMath.CategoryTheory.Core.Prelude UniMath.CategoryTheory.TwoSidedDisplayedCats.TwoSidedDispCat UniMath.CategoryTheory.TwoSidedDisplayedCats.Isos UniMath.CategoryTheory.TwoSidedDisplayedCats.Univalence UniMath.CategoryTheory.TwoSidedDisplayedCats.Discrete UniMath.Bicategories.Core.Bicat UniMath.Bicategories.Core.Univalence UniMath.Bicategories.DoubleCategories.DoubleBicat.VerityDoubleBicat UniMath.Bicategories.DoubleCategories.DoubleBicat.DerivedLaws UniMath.Bicategories.DoubleCategories.DoubleBicat.UnderlyingCats UniMath.Bicategories.DoubleCategories.DoubleBicat.CellsAndSquares