Duval–Reiner conjecture for simplicial-complex Laplacians

From papers

Let KK be a kk-family on vertex set V(K)V(K). Let k1\partial_{k-1} be its boundary operator, and let s=(s1s2)\mathbf{s}=(s_1\ge s_2\ge\cdots) be the nonincreasing sequence of nonzero eigenvalues of k1k1\partial_{k-1}\partial_{k-1}^*. Let d=(d1d2)\mathbf{d}=(d_1\ge d_2\ge\cdots) be the vertex degree sequence of KK, and let d\mathbf{d}^\top be its conjugate sequence. For nonincreasing sequences x\mathbf{x} and y\mathbf{y}, xy\mathbf{x}\prec\mathbf{y} means that their partial sums satisfy the majorization inequalities and their total sums are equal.

Duval–Reiner conjecture. The eigenvalue sequence is majorized by the conjugate vertex degree sequence:

sd.\mathbf{s}\prec\mathbf{d}^\top.

This is proposed as a far-reaching analogue of the Grone–Merris conjecture for simplicial complexes. The supplied text does not state whether the conjecture has been proved or refuted.

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Sources & referencesView supporting material

Primary source

Yueli Han, Lu Lu and Jianfeng Wang, “On the sum of the two largest eigenvalues of the curl-curl operator on graphs”, arXiv:2606.26512 (2026).

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