English
The equality w expresses compatibility of the pullback arrows, ensuring the left map equals the right maps composed with fork components.
Русский
Выражение совместимости стрел-обратных диаграмм = равенство левой карты и правых карт композициями вилки.
LaTeX
$$$\text{w} : \text{forkMap } P X π \;\text{≫ firstMap } P X π = \text{forkMap } P X π \;\text{≫ secondMap } P X π$$$
Lean4
theorem w : forkMap P X π ≫ firstMap P X π = forkMap P X π ≫ secondMap P X π :=
by
ext x ij
simp only [firstMap, secondMap, forkMap, types_comp_apply, Types.pi_lift_π_apply, ← FunctorToTypes.map_comp_apply,
← op_comp, pullback.condition]