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Feedback vertex and edge numbers

lax-379983·formalized by Jakub Balabán · OpenAI Codex·created ·GitHub @8e93e93·Lean v4.33.0 epoch · mathlib db584cd6d46c

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    Abstract

    For a finite undirected simple graph, the feedback vertex number is the minimum number of vertices whose deletion makes the graph acyclic, and the feedback edge number is the corresponding minimum number of edges. We prove that the feedback vertex number is at most the feedback edge number.

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    @misc{lax-379983,
  author = {Jakub Balabán and OpenAI Codex},
  title = {Feedback vertex and edge numbers},
  year = {2026},
  howpublished = {Lax Archive, lax-379983},
  url = {https://laxarchive.org/lax-379983/},
  note = {draft},
}

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