The componentwise inertia sum-of-squares conjecture
Let be a simple undirected graph with vertices and connected components. Let be the eigenvalues of its adjacency matrix, and let and be the numbers of positive and negative eigenvalues, counted with multiplicity. Define
Componentwise inertia sum-of-squares conjecture. One has
For a connected graph, this specializes to the conjectured lower bound , and either one-sided inequality implies the corresponding Hong-type bound. The supplied source gives no evidence of a resolution for the general disconnected-graph formulation.
References
Primary source
Clive Elphick, Felix Goldberg, Miriam Farber and Pawel Wocjan, “Conjectured bounds for the sum of squares of positive eigenvalues of a graph”, arXiv:1409.2079 (2015).
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