Lesson 178

Network Flow

Max Flow · Ford–Fulkerson · Min Cut

1:00

How to maximize flow through a capacity-constrained directed network using Ford-Fulkerson augmenting paths, the residual graph, and the max-flow min-cut theorem.

By the end, you can

  • Define the capacity constraint and conservation rule, and verify whether a given flow is valid.
  • Identify the source, sink, augmenting paths, and bottleneck in a concrete flow network.
  • Trace the Ford-Fulkerson algorithm step by step, updating flows and residual edges.
  • Explain why residual backward edges are essential for correctness, not just a bookkeeping trick.
  • Compute the max flow of a small network by hand and confirm it matches the minimum cut.
  • Define an S-T cut, compute its capacity, and identify the minimum cut in a small network.
  • State the max-flow min-cut theorem and explain what it implies about the termination of Ford-Fulkerson.
  • Compare the time complexity of Ford-Fulkerson O(E·maxflow) and Edmonds-Karp O(V·E²).
  • Describe how bipartite matching, image segmentation, and network routing reduce to max-flow.
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