feedback arc set
... that for round-robin sports tournaments, finding a ranking of the competitors that minimizes the number of upset games is an instance of the feedback arc set problem?
... that for <a href="./Round-robin_tournament" id="mwB5A" rel="mw:WikiLink" title="Round-robin tournament">round-robin sports tournaments</a>, finding a <a href="./Group_tournament_ranking_system" id="mwB5E" rel="mw:WikiLink" title="Group tournament ranking system">ranking of the competitors</a> that minimizes the number of upset games is an instance of the <b id="mwB5I"><a href="./Feedback_arc_set" id="mwB5M" rel="mw:WikiLink" title="Feedback arc set">feedback arc set</a></b> problem?