English
There is an associator providing a bialgebra equivalence between (A ⊗_S C) ⊗_R D and A ⊗_S (C ⊗_R D) for suitable A,B,C,D with the given scalar-tower and bialgebra structures.
Русский
Существуют ассоциатор и соответствующая билигебра-эквивалентность между (A ⊗_S C) ⊗_R D и A ⊗_S (C ⊗_R D) при наличии заданных структур скаляров и билингв.
LaTeX
$$$\text{assoc} : (A \otimes_S C) \otimes_R D \cong_c[S] A \otimes_S (C \otimes_R D)$$$
Lean4
/-- The associator for tensor products of R-bialgebras, as a bialgebra equivalence. -/
protected noncomputable def assoc : (A ⊗[S] C) ⊗[R] D ≃ₐc[S] A ⊗[S] (C ⊗[R] D) :=
{ Coalgebra.TensorProduct.assoc R S A C D, Algebra.TensorProduct.assoc R S A C D with }