The exact L(3,2,1)-labeling number of odd 4-valent circulants with steps 1 and 5
The exact L(3,2,1)-labeling number of odd 4-valent circulants with steps 1 and 5
Let be odd with , and let . The invariant is the minimum span of an -labeling of , meaning a labeling of the vertices by nonnegative integers such that labels of vertices at distances , , and differ by at least , , and , respectively.
Exact labeling-number conjecture.
The source constructs an -labeling with span for the stated range, while computer tests found no labeling with labels for odd . Thus the conjecture combines the construction with the expected lower bound for all odd .
Progress summary
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Sources & referencesView supporting material
Primary source
Přemysl Holub and Martin Kopřiva, “L(3,2,1)-labelings of three classes of 4-valent circulants”, arXiv:2601.12574 (2026).
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