 Dung’s approach doesn’t distinguish between the various ways in which one argument can attack another, such as rebutting, undermining, or undercutting, although this additional information can be added by differentiating several types of attack relations. One argument rebuts another when their conclusions are contradictories. An argument undermines a second argument when the conclusion of the first contradicts one of the premises of the second. And an argument undercuts another when its conclusion provides reason for doubting that the premises of the second are in the actual circumstances reliable indicators of the truth of the conclusion. In many applications, these distinctions can be ignored. However, Henry Prakken (Prakken 2010) makes use of all three forms of attack in his ASPIC+ system.