# neighborhood retract

Let $X$ be a topological space and $Y$ a subspace of $X$. If there exists an open set $U$ such that $Y\subset U\subset X$ and $Y$ is a retract of $U$, then we say $Y$ is a neighborhood retract of $X$.

Title neighborhood retract NeighborhoodRetract 2013-03-22 14:39:41 2013-03-22 14:39:41 rspuzio (6075) rspuzio (6075) 5 rspuzio (6075) Definition msc 54A99