Solution
= Solution
A <topological sort> is \b[a linear ordering of all <vertices> of a <Directed acyclic graph> in which every directed edge points from an earlier vertex to a later one]. For example, with $V=\{a,b,c\}$ and $E=\{(a,c),(b,c)\}$, both $(a,b,c)$ and $(b,a,c)$ are <topological sorts>. They differ because neither edge nor directed path constrains the relative order of $a$ and $b$.