proposition: Lemma whisker_left_left {C : prebicategory} {a b c d : C} (f : a -1-> b) (g : b -1-> c) {h i : c -1-> d} (x : h -2-> i) : whisker_left f (whisker_left g x) ;v; associator_2mor f g i = associator_2mor f g h ;v; whisker_left (f ;1; g) x.
proof: Proof. unfold whisker_left. etrans; [ apply associator_naturality | idtac]. apply maponpaths. apply maponpaths_2. exact horizontal_comp_id. Defined.
imports: UniMath.Foundations.All UniMath.MoreFoundations.All UniMath.CategoryTheory.Core.Categories UniMath.CategoryTheory.Core.Isos UniMath.CategoryTheory.Core.Univalence UniMath.CategoryTheory.Core.Functors UniMath.CategoryTheory.PrecategoryBinProduct UniMath.CategoryTheory.HorizontalComposition UniMath.Bicategories.WkCatEnrichment.prebicategory UniMath.Bicategories.WkCatEnrichment.whiskering UniMath.Bicategories.Core.Bicat UniMath.Bicategories.WkCatEnrichment.Notations