Low-Link Example

Graph: $1-2$, $2-3$, $3-1$, $2-4$. Start DFS at $1$. Discovery times: disc[1]=0, disc[2]=1, disc[3]=2, disc[4]=3. Low-link values: low[1]=0 (reaches itself), low[2]=0 (back edge $3-1$ reaches $1$), low[3]=0 (back edge $3-1$), low[4]=3 (no back edges, dead end).

Edge $2-4$ is a bridge because low[4]=3 > disc[2]=1. The subtree of $4$ cannot reach anything earlier than $4$ itself. Removing edge $2-4$ disconnects node $4$ from the rest.