 A final step is needed to also capture non-direct causal relations. \(C\) is a cause of \(E,\) possibly non-direct, iff the ordered pair \((C,E)\) is in the transitive closure of the relation of direct causation. That is, \(C\) is a cause of \(E\) iff there is a sequence \(\langle C, C_1, \ldots, C_n, E \rangle\) \((n\geq 0)\) such that each element of the sequence is a direct cause of the successor (if there is one).