English

Explicit Factorization of $x^{p+1}-1$ over $\mathbb{Z}_{p^e}$: A Structural Approach via Dickson Polynomials

Information Theory 2026-04-22 v1 math.IT

Abstract

Let pp be an odd prime. The factorization of the polynomial xp+11x^{p+1}-1 over the integer residue ring Zpe\mathbb{Z}_{p^e} is pivotal for constructing cyclic codes with Hermitian symmetry, a critical resource for Linear Complementary Dual (LCD) codes and Entanglement-Assisted Quantum Error-Correcting Codes (EAQECC). Traditionally, lifting factorizations relies on the generic Hensel's Lemma, masking the underlying algebraic structure. In this paper, we establish a structural isomorphism between the lifting process and the roots of a special auxiliary polynomial V(x)V(x), unveiling a deterministic link to Dickson polynomials. Based on this theory, we develop \texttt{Dickson-Engine}, a linear-time algorithm (O(ep)O(ep)) that outperforms standard libraries by orders of magnitude. Applying this engine to Z169\mathbb{Z}_{169}, we explicitly construct a family of classical LCD codes of length n=182n=182 via the isometric Gray map. Our search reveals codes with parameters (e.g., [182,1,168]13[182, 1, 168]_{13} and [182,2,144]13[182, 2, 144]_{13}) that are \textbf{near-optimal} with respect to the theoretical Griesmer Bound. Notably, we discover a ``robustness plateau'' starting from non-trivial dimensions (k=4k=4), where the minimum distance remains stable (d=120d=120) even as the dimension triples (k=412k=4 \rightarrow 12). These codes provide exceptional resources for post-quantum cryptography and quantum error correction without entanglement consumption (c=0c=0).

Keywords

Cite

@article{arxiv.2604.19038,
  title  = {Explicit Factorization of $x^{p+1}-1$ over $\mathbb{Z}_{p^e}$: A Structural Approach via Dickson Polynomials},
  author = {Yongchao Wang and Yang Ding and Jiansheng Yang and Zhiqiu Huang},
  journal= {arXiv preprint arXiv:2604.19038},
  year   = {2026}
}

Comments

This is the full and extended version of the paper accepted to the IEEE International Symposium on Information Theory (ISIT). It provides complete mathematical proofs, simple illustrative factorization examples, and a detailed design analysis on 'Sparsity vs. Density of Generator Polynomials' that were omitted from the conference proceedings due to space limitations

R2 v1 2026-07-01T12:27:40.497Z