A residual connection, or skip connection, creates a pathway around intermediate GNN layers so information can bypass local processing and retain longer-range signals. section 5.5.2
Use residual connections when:
- Deep message passing causes over-smoothing, making node representations increasingly similar after roughly three or four layers. section 5.5.2
- Long-range interactions matter but stacking enough layers to match the problem radius would intensify over-squashing. section 5.5.2
- You need an alternative or complement to attention mechanisms, neighborhood sampling, added edges, or globally connected nodes. section 5.5.2
Figure 5.19 Visualization of over-squashing (Source: Alon and Yahav [7])
Visualize how information becomes compressed across graph distance and why bypass pathways can help preserve distant signals. section 5.5.2











