Submitted:
05 November 2026
Posted:
09 November 2026
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Abstract
We prove that the packing chromatic number of the generalized Sierpiński graph over the five-cycle is six in every dimension at least two. Together with the known values for the other cycle bases of length at least four, this completes their classification. Two explicit 125-vertex templates and twenty oriented profile states provide the construction. Each state admits two independently selectable productions, yielding at least 20 · 2^((5^(n−3)−1)/4) optimal labelled colorings in dimension n ≥ 3; their normalized base-two logarithmic count has a limit of at least 1/500. For Sierpiński path products, we determine the maximum packing chromatic number throughout the previously unresolved range m ≥ 12, n ≥ 3: it is seven exactly when m ≥ 20, n ≥ 5, and six otherwise. The proof gives two sharp structural guarantees for trees with at most two pendant paths at each spine vertex: nineteen spine vertices, or sixteen vertices bearing two arms of length at least two, suffice for six colors. Explicit examples show both guarantees are sharp. The finite computations have standalone certificates; the unbounded claims follow from the stated constructions, closure arguments, and induction.
Keywords:
packing coloring
; generalized Sierpi´nski graphs
; Sierpi´nski products
; graph coloring
; computer-assisted proof
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