Retraction
Set
| $X,S$ |
| $S\subseteq X$ |
| $ \{\rho\} $ |
|---|
| $ \rho:X\to S $ |
| $ \rho_{|S}=\text{id}_S $ |
|---|
Ramifications
Reference
Wikipedia: Deformation retract
| $X,S$ |
| $S\subseteq X$ |
| $ \{\rho\} $ |
|---|
| $ \rho:X\to S $ |
| $ \rho_{|S}=\text{id}_S $ |
|---|
Wikipedia: Deformation retract