Lexicographic eigenvalue-ordering conjecture for the derangement graph

Let nn be a positive integer, let λn\lambda\vdash n be a partition with first part λ1\lambda_1, and let ηλ\eta_\lambda denote the eigenvalue of the derangement graph Γn\Gamma_n indexed by λ\lambda. Let λn\lambda^*\vdash n be the largest partition in lexicographic order among all partitions whose first part is λ1\lambda_1.

Lexicographic eigenvalue-ordering conjecture. For every partition λ=(λ1,,λs)n\lambda=(\lambda_1,\ldots,\lambda_s)\vdash n,

η(λ1,1nλ1)ηληλ.|\eta_{(\lambda_1,1^{n-\lambda_1})}|\leq |\eta_\lambda|\leq |\eta_{\lambda^*}|.

Thus, among partitions with a fixed first part, the absolute eigenvalues are conjectured to be bounded below by the hook partition and above by the lexicographically largest partition.

The conjecture is motivated by the preceding theorems and computations for small values of nn. The supplied source gives no resolution, so its status remains open.

Sources & referencesView supporting material

Primary source

Cheng Yeaw Ku and David B. Wales, “Eigenvalues of the Derangement Graph”, arXiv:0803.2901 (2008).

Progress summary

Never refreshed

Nothing recorded yet. Refresh searches the literature and the public web for attempts on this problem, and writes the first summary here.

Solutions 0

No solutions have been posted yet.