Non-splitting bi-unitary perfect polynomials over $\mathbb{F}_4$ with less than five prime factors
Olivier Rahavandrainy
TL;DR
This work completes the classification of non-splitting bi-unitary perfect polynomials over $\mathbb{F}_4$ with at most four irreducible factors by separating splitting and non-splitting cases. For splitting polynomials, it consolidates known results and reproduces the four admissible families, along with a complete list of perfect polynomials in this setting. For non-splitting polynomials, it shows $\omega(A)=2$ yields $A=P^hQ^k$ with $Q=P+1$ and $(h,k)=(2,2)$ or $(2^r-1,2^r-1)$, while $\omega(A)=3$ is impossible; for $\omega(A)=4$ it derives two structured families with $P\in\Omega_2$, $Q=P+1$, and $R,S$ among $\{P^3+P+1,P^3+P^2+1\}$, specifically with $(h,k,l,t)=(7,13,2,2),(13,7,2,2),(14,14,2,2)$. These results are supported by explicit Maple verification. The findings reveal both infinite families in the splitting case and a finite, highly structured set in the non-splitting case, advancing understanding of bi-unitary perfection over $\mathbb{F}_4$.
Abstract
We identify all non-splitting bi-unitary perfect polynomials over the field $\mathbb{F}_4$, which admit at most four irreducible divisors. There is an infinite number of such divisors.
