Permanental rank versus determinantal rank of random matrices over finite fields

Fuente: arXiv
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Hauptverfasser: Ghasemi, Fatemeh, Gross, Gal, Kopparty, Swastik
Format: Preprint
Veröffentlicht: 2025
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author Ghasemi, Fatemeh
Gross, Gal
Kopparty, Swastik
author_facet Ghasemi, Fatemeh
Gross, Gal
Kopparty, Swastik
contents This paper is motivated by basic complexity and probability questions about permanents of random matrices over finite fields, and in particular, about properties separating the permanent and the determinant. Fix $q = p^m$ some power of an odd prime, and let $k \leq n$ both be growing. For a uniformly random $n \times k$ matrix $A$ over $\mathbb{F}_q$, we study the probability that all $k \times k$ submatrices of $A$ have zero permanent; namely that $A$ does not have full "permanental rank". When $k = n$, this is simply the probability that a random square matrix over $\mathbb{F}_q$ has zero permanent, which we do not understand. We believe that the probability in this case is $\frac{1}{q} + o(1)$, which would be in contrast to the case of the determinant, where the answer is $\frac{1}{q} + Ω_q(1)$. Our main result is that when $k$ is $O(\sqrt{n})$, the probability that a random $n \times k$ matrix does not have full permanental rank is essentially the same as the probability that the matrix has a $0$ column, namely $(1 +o(1)) \frac{k}{q^n}$. In contrast, for determinantal (standard) rank the analogous probability is $Θ(\frac{q^k}{q^n})$. At the core of our result are some basic linear algebraic properties of the permanent that distinguish it from the determinant.
format Preprint
id arxiv_https___arxiv_org_abs_2512_03221
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Permanental rank versus determinantal rank of random matrices over finite fields
Ghasemi, Fatemeh
Gross, Gal
Kopparty, Swastik
Computational Complexity
Combinatorics
Probability
68Q17 (Primary) 15A15, 15B33, 15B52 (Secondary)
F.1.m
This paper is motivated by basic complexity and probability questions about permanents of random matrices over finite fields, and in particular, about properties separating the permanent and the determinant. Fix $q = p^m$ some power of an odd prime, and let $k \leq n$ both be growing. For a uniformly random $n \times k$ matrix $A$ over $\mathbb{F}_q$, we study the probability that all $k \times k$ submatrices of $A$ have zero permanent; namely that $A$ does not have full "permanental rank". When $k = n$, this is simply the probability that a random square matrix over $\mathbb{F}_q$ has zero permanent, which we do not understand. We believe that the probability in this case is $\frac{1}{q} + o(1)$, which would be in contrast to the case of the determinant, where the answer is $\frac{1}{q} + Ω_q(1)$. Our main result is that when $k$ is $O(\sqrt{n})$, the probability that a random $n \times k$ matrix does not have full permanental rank is essentially the same as the probability that the matrix has a $0$ column, namely $(1 +o(1)) \frac{k}{q^n}$. In contrast, for determinantal (standard) rank the analogous probability is $Θ(\frac{q^k}{q^n})$. At the core of our result are some basic linear algebraic properties of the permanent that distinguish it from the determinant.
title Permanental rank versus determinantal rank of random matrices over finite fields
topic Computational Complexity
Combinatorics
Probability
68Q17 (Primary) 15A15, 15B33, 15B52 (Secondary)
F.1.m
url https://arxiv.org/abs/2512.03221