English
The left-right homology comparison equals the description morphism built by applying a left-descending construction followed by a lifting from the right, under suitable conditions.
Русский
Сопоставление левой и правой гомологий равно описывающему отображению, получаемому последовательностью конструкций слева и подъёма справа при подходящих условиях.
LaTeX
$$$\\text{leftRightHomologyComparison}'(h_1,h_2) = h_1.\\mathrm{descH}\\bigl( h_2.\\mathrm{liftH}(h_1.\\mathrm{i} \\circ h_2.\\mathrm{p}) \\bigr)$$$
Lean4
theorem leftRightHomologyComparison'_eq_descH :
leftRightHomologyComparison' h₁ h₂ =
h₁.descH (h₂.liftH (h₁.i ≫ h₂.p) (by simp))
(by
rw [← cancel_mono h₂.ι, assoc, RightHomologyData.liftH_ι, LeftHomologyData.f'_i_assoc, RightHomologyData.wp,
zero_comp]) :=
by
simp only [← cancel_mono h₂.ι, ← cancel_epi h₁.π, π_leftRightHomologyComparison'_ι, LeftHomologyData.π_descH_assoc,
RightHomologyData.liftH_ι]