Bridges (Tarjan DFS)

Robert Tarjan, 1974

In 1974 Tarjan observed that an edge (parent, child) in the DFS tree is a bridge exactly when low[child] exceeds disc[parent], because no cycle reconnects the subtree. This exhibit animates two fused triangles linked by a single cut edge C–D; the DFS glows in gold, tentative scans pulse the explored edge, and the eventual bridge glows coral while finished components tint teal in the epilogue.