Poisson distribution conjecture for cokernels of random matrices over p-adic integers

From papers

Let Zp\mathbb{Z}_{p} be the ring of pp-adic integers. Fix distinct d1,,drZ1d_{1},\dots,d_{r}\in\mathbb{Z}_{\geq 1} and not necessarily distinct k1,,krZ0k_{1},\dots,k_{r}\in\mathbb{Z}_{\geq 0}. For each dd, let M(d,p)\mathcal{M}(d,p) be the set of monic irreducible polynomials of degree dd in Fp[t]\mathbb{F}_{p}[t]. For (Pˉ1,,Pˉr)j=1rM(p,dj)(\bar{P}_{1},\dots,\bar{P}_{r})\in\prod_{j=1}^{r}\mathcal{M}(p,d_{j}), let PjP_{j} be any lift of Pˉj\bar{P}_{j} to Zp[t]\mathbb{Z}_{p}[t], and let AA be Haar-random in Matn(Zp)\operatorname{Mat}_{n}(\mathbb{Z}_{p}). Poisson distribution conjecture. The limit

limpProbAMatn(Zp)(coker(Pj(A))=pdjkjfor all (Pˉ1,,Pˉr)j=1rM(p,dj))\lim_{p\to\infty}\operatorname{Prob}_{A\in\operatorname{Mat}_{n}(\mathbb{Z}_{p})}\left(\begin{array}{c}|\operatorname{coker}(P_{j}(A))|=p^{d_{j}k_{j}}\text{for all }(\bar{P}_{1},\dots,\bar{P}_{r})\in\prod_{j=1}^{r}\mathcal{M}(p,d_{j})\end{array}\right)

must exist, and

limnlimpProbAMatn(Zp)(coker(Pj(A))=pdjkjfor all (Pˉ1,,Pˉr)j=1rM(p,dj))=j=1re1/dj(1/dj)kjkj!.\lim_{n\to\infty}\lim_{p\to\infty}\operatorname{Prob}_{A\in\operatorname{Mat}_{n}(\mathbb{Z}_{p})}\left(\begin{array}{c}|\operatorname{coker}(P_{j}(A))|=p^{d_{j}k_{j}}\text{for all }(\bar{P}_{1},\dots,\bar{P}_{r})\in\prod_{j=1}^{r}\mathcal{M}(p,d_{j})\end{array}\right)=\prod_{j=1}^{r}\frac{e^{-1/d_{j}}(1/d_{j})^{k_{j}}}{k_{j}!}.

This conjecture generalizes the preceding theorem, whose limiting probability for all the cokernels to be trivial is j=1re1/dj\prod_{j=1}^{r}e^{-1/d_{j}}. The claimed formula is the joint distribution of independent Poisson random variables with means 1/d1,,1/dr1/d_{1},\dots,1/d_{r}. The authors report little empirical evidence and invite further examples supporting or disproving it, so its status remains open.

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Sources & referencesView supporting material

Primary source

Gilyoung Cheong, Jungin Lee, Hayan Nam and Myungjun Yu, “Jordan–Landau theorem for matrices over finite fields”, arXiv:2005.07846 (2022).

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