E 1 → f E 2 π 1 ↓ ↓ π 2 X 1 → g X 2 {\displaystyle {\begin{aligned}E_{1}&{\xrightarrow {f}}&E_{2}\\\pi _{1}{\Bigg \downarrow }&&{\Bigg \downarrow }{\pi _{2}}&\\X_{1}&{\xrightarrow[{g}]{}}&X_{2}\end{aligned}}}
↓ [ π 1 ] K 3 {\displaystyle {\Bigg \downarrow }[\pi _{1}]{K_{3}}}
![{\displaystyle {\begin{aligned}E_{1}&{\xrightarrow {f}}&E_{2}\\\pi _{1}{\Bigg \downarrow }&&{\Bigg \downarrow }{\pi _{2}}&\\X_{1}&{\xrightarrow[{g}]{}}&X_{2}\end{aligned}}}](https://wikimedia.org/api/rest_v1/media/math/render/svg/4bb0d8c5918f455a2fa8e6834142e0d99221ea8b)
![{\displaystyle {\Bigg \downarrow }[\pi _{1}]{K_{3}}}](https://wikimedia.org/api/rest_v1/media/math/render/svg/70d19977cb7a79df9378fbbc414920042e82a98d)
