Element of a set
= Element of a set
{title2=$a\in A$}
{wiki}
= Set element
{synonym}
A set element is an object belonging to a <set>. The statement $a\in A$ asserts membership; $a\notin A$ denies it. Membership differs from inclusion: $a\in A$ concerns one member, whereas $B\subseteq A$ asserts that every <set element> of $B$ belongs to $A$.