Path reversal
= Path reversal
The reverse of a path $\alpha$ is $\bar\alpha(t)=\alpha(1-t)$. Concatenating a path with its reverse is homotopic relative to endpoints to the constant path.
= Path reversal
The reverse of a path $\alpha$ is $\bar\alpha(t)=\alpha(1-t)$. Concatenating a path with its reverse is homotopic relative to endpoints to the constant path.