Special labelled h-factor realization conjecture

Let n∈Nn\in\mathbb{N}, let d1≥d2≥⋯≥dn≥1d_1\ge d_2\ge\dots\ge d_n\ge1 be integers, and let hh be a positive integer. The labelled h-factor is

{(1,2,…,h+1),…,(n−h,…,n)},\{(1,2,\ldots,h+1),\ldots,(n-h,\ldots,n)\},

where each tuple denotes the complete graph on its listed vertices. Special labelled h-factor conjecture. The sequence (d1,d2,…,dn)(d_1,d_2,\ldots,d_n) can realize this h-factor if and only if ∑i=1ndi\sum_{i=1}^n d_i is even, nn is a multiple of h+1h+1, and, for every k∈[n]k\in[n],

∑i=1kdi≤k(k−1)+∑i=k+1k+1+h−smin⁡{di−h+s,k}+∑i=k+1+h−s+1nmin⁡{di−h,k},\sum_{i=1}^k d_i\le k(k-1)+\sum_{i=k+1}^{k+1+h-s}\min\{d_i-h+s,k\}+\sum_{i=k+1+h-s+1}^n\min\{d_i-h,k\},

where s∈{0,…,h}s\in\{0,\ldots,h\} and s≡k(modh+1)s\equiv k\pmod{h+1}. The conjecture is open in general; the source cites partial results and uses it as an assumption for a subsequent corollary.

References

Primary source

Joseph Briggs, Jessica McDonald and Songling Shan, “Degree sequences realizing labelled perfect matchings”, arXiv:2510.01110 (2025).

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