Homotopy group
= Homotopy group
{title2=$\pi_n(X,x_0)$}
{wiki}
The $n$th homotopy group consists of based homotopy classes of maps $S^n\to X$. It is a group for $n\geq1$ and an <abelian group> for $n\geq2$.
= Homotopy group
{title2=$\pi_n(X,x_0)$}
{wiki}
The $n$th homotopy group consists of based homotopy classes of maps $S^n\to X$. It is a group for $n\geq1$ and an <abelian group> for $n\geq2$.