English
There is a natural isomorphism μNatIso between the tensoring of F with itself and the tensoring after F, i.e., a canonical tensorator for F.
Русский
Существует естественная изоморфность μNatIso между F×F ⋙ tensor_D и tensor_C ⋙ F.
LaTeX
$$$$ \\mu\\mathrm{NatIso} : (F \\mathrm{prod} F) \\;\\circ\\; \\mathrm{tensor}_D \\cong \\mathrm{tensor}_C \\circ F $$$$
Lean4
theorem toLaxMonoidal_injective :
Function.Injective (@Monoidal.toLaxMonoidal _ _ _ _ _ _ _ : F.Monoidal → F.LaxMonoidal) :=
by
intro a b eq
ext1
· exact congr(($eq).ε)
· exact congr(($eq).μ)
· rw [← cancel_epi (εIso _).hom]
rw [εIso_hom, ε_η, ← @ε_η _ _ _ _ _ _ _ a, ← εIso_hom]
exact congr(($eq.symm).ε ≫ _)
· ext
rw [← cancel_epi (μIso F _ _).hom]
rw [μIso_hom, μ_δ, ← @μ_δ _ _ _ _ _ _ _ a, ← μIso_hom]
exact congr(($eq.symm).μ _ _ ≫ _)