Chartrand–Holbert–Oellermann–Swart conjecture on F-irregular graphs
Chartrand–Holbert–Oellermann–Swart conjecture on F-irregular graphs
Let be a connected graph of order at least . A graph is -irregular if every vertex of has a distinct number of subgraphs isomorphic to that contain it. A graph is nontrivial if it has at least one edge.
Chartrand–Holbert–Oellermann–Swart conjecture. For every connected graph of order at least , there exists a nontrivial -irregular graph.
The conjecture generalizes the distinction of vertices by ordinary degree, corresponding to , for which no nontrivial graph is -irregular. It is known for several classes, including stars, complete graphs, and paths, but is not stated as fully resolved here.
Sources & referencesView supporting material
Primary source
Tatiana Dovzhenok, “From roots to paths: graphs simultaneously irregular with respect to rooted and ordinary paths”, arXiv:2607.11700 (2026).
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