Induced linear map on a quotient vector space (source code)

= Induced linear map on a quotient vector space
{title2=$\overline T(v+U)=T(v)+U$}

= Induced linear maps on quotient vector spaces
{synonym}

For a <linear map> $T:V\to V$ and an <invariant subspace> $U$, the rule $\overline T(v+U)=T(v)+U$ defines a <linear map> on the <quotient vector space> $V/U$. Indeed, two representatives differ by an element of $U$, so their images also differ by an element of $U$. Conversely, this rule is well-defined only if $T(U)\subseteq U$, by comparing every $u\in U$ with zero.