Null-homotopy
= Null-homotopy
{title2=$H:f\simeq c$}
A <null-homotopy> of a <continuous map> $f:X\to Y$ is a <homotopy> from $f$ to a <constant function> $c:X\to Y$. Existence of such a <homotopy> means precisely that $f$ is <null-homotopic>.
= Null-homotopy
{title2=$H:f\simeq c$}
A <null-homotopy> of a <continuous map> $f:X\to Y$ is a <homotopy> from $f$ to a <constant function> $c:X\to Y$. Existence of such a <homotopy> means precisely that $f$ is <null-homotopic>.