Reversal-Wilf conjecture for contraction containment in labeled trees
Reversal-Wilf conjecture for contraction containment in labeled trees
Let denote the set of labeled trees on . For and , write if displays , meaning that can be obtained from by contracting connected fibers and then standardizing the survivor labels. Define the support count by
Let be label reversal, . Reversal-Wilf conjecture. For , if
then or . Reversal of the ambient label set already gives for all , so the conjecture asserts that these are the only equal support-count sequences. It asks whether contraction containment among labeled trees has no Wilf-equivalences beyond label reversal.
Sources & referencesView supporting material
Primary source
Levi Segal, “Structure, Enumeration, and star avoidance for contraction containment in labeled trees”, arXiv:2606.07668 (2026).
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