Feedback arc set

Feedback arc set --- разрывающее множество дуг.

Given a digraph [math]\displaystyle{ G = (V,A) }[/math], an arc set [math]\displaystyle{ B \subseteq A }[/math] is called a feedback arc set if the digraph [math]\displaystyle{ G - B }[/math], resulting from [math]\displaystyle{ G }[/math] by deleting all the arcs of [math]\displaystyle{ B }[/math] from [math]\displaystyle{ G }[/math], is DAG. FAS-problem is the problem of looking for a minimum feedback arc set.