English

On the computation of $\mathrm{Ext}_{\mathcal A}^{k,k+*}(\mathbb{Z}/2,\mathbb{Z}/2)$ for $k \leq 5$

Algebraic Topology 2025-09-19 v3 Geometric Topology Rings and Algebras

Abstract

This Note presents a computational algorithm for determining a basis of the cohomology of the mod 2 Steenrod algebra, ExtAk,k+(Z/2,Z/2)\mathrm{Ext}_{\mathcal A}^{k, k+*}(\mathbb{Z}/2, \mathbb{Z}/2) for k5k \leq 5, based on the well-known generators and the Adams relations given in Chen's work [2]. The purpose of this algorithm is to verify the hand-computed results for ExtA4,4+(Z/2,Z/2)\mathrm{Ext}_{\mathcal A}^{4, 4+*}(\mathbb{Z}/2, \mathbb{Z}/2) presented in our corrected papers [8, 9, 10]. Combining our most recent works [11, 12], the verification of the domain and the codomain of the fourth algebraic transfer in specific degrees can now be completed.

Keywords

Cite

@article{arxiv.2507.15611,
  title  = {On the computation of $\mathrm{Ext}_{\mathcal A}^{k,k+*}(\mathbb{Z}/2,\mathbb{Z}/2)$ for $k \leq 5$},
  author = {Dang Vo Phuc},
  journal= {arXiv preprint arXiv:2507.15611},
  year   = {2025}
}

Comments

21 pages. Any constructive suggestions are most welcome