With this additional gating mechanism, the final syntactic GCN computation is formulated as The inability of GCNs to capture dependencies between nodes far away from each other in the graph may seem like a serious problem, especially in the context of SRL: paths between predicates and arguments often include many dependency arcs (Roth and Lapata, 2016).
when graph convolution is performed on top of LSTM states (i.e., LSTM states serve as input to GCN) rather than static word embeddings, GCN may not need to capture more than a couple of hops.