MathGloss
A
left ideal
of a
ring
$R$ is a subset $I\subseteq R$ such that
$(I,+)$ is a
subgroup
of $(R,+)$;
$I$ is closed under left multiplication in $R$ (i.e. for all $i\in R$ and all $r\in R$, $ri \in I$).
Wikidata ID:
Q44649