\textbf{The argument graph}$G =(A, E)$\textbf{ is a directed graph with:}
\begin{itemize}
\item Each argument-node $a_i \in A$ consisting of a conclusion $c_i$ and a not-empty set of premises $P_i$$\Rightarrow$$a_i =\langle c_i, P_i \rangle$
\item An edge $(a_j, a_i)$ is given if the conclusion $a_j$ is used as a premise of $a_i$
\item Consequently, $P_i =\{c_1,...,c_k\}, k \geq1$