Combinatorics Seminar | Le Chen, Auburn University

Based on joint work with Songling Shan. How can a graph require four edge colors even though every vertex has degree at most three — and become three-edge-colorable whenever any edge is removed? We introduce these critical graphs from first principles, present an all-order structural characterization, and describe an exhaustive computational census. We also discuss the HPC and AI-assisted research infrastructure that made the search possible.

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