Hi! Suppose we have a 2-fold covering $\displaystyle p: E \rightarrow B$ and we construct the mapping cylinder $\displaystyle C_p$ of the projection. Why is $\displaystyle E$ the boundary of $\displaystyle C_p$?
best greetings
Hi! Suppose we have a 2-fold covering $\displaystyle p: E \rightarrow B$ and we construct the mapping cylinder $\displaystyle C_p$ of the projection. Why is $\displaystyle E$ the boundary of $\displaystyle C_p$?
best greetings