Homology Nilpotency in Rational Homotopy Theory: Cell Attachments, Retractive Towers, Divergence, and Stabilization
Abstract
Homology nilpotency of a simply connected minimal Sullivan algebra M is the least integer n for which (M+)n+1 is contained in an acyclic differential ideal. We develop lower- and upper-bound criteria, including methods for rational cell attachments, and construct an explicit finite-type minimal Sullivan algebra M satisfying nilh(M)=3<Hnil(M)=4. Complete strictly coordinated retractive towers identify the obstruction: they characterize homotopical nil-length while exposing the additional quotient defect measured by homology nilpotency. We then show that this rigid defect disappears after stabilization by degreewise finite wedges of simply connected rational spheres: Hnils(X)=cato(X) for every simply connected rational space X of finite type.
Related
- Homotopical Nilpotency and Homology Nilpotency: A Dimension--Connectivity Bound
- A sphere-product counterexample to the additivity of homology nilpotency
- Sectional category versus module sectional category for retractive maps
- On nilpotency in pre - Lie algebras
- Nilpotency and nil subvarieties of binary Zinbiel algebras
BibTeX
@misc{parent2026homology,
title = {{Homology Nilpotency in Rational Homotopy Theory: Cell Attachments, Retractive Towers, Divergence, and Stabilization}},
author = {Paul-Eugène Parent},
howpublished = {arXiv},
year = {2026},
month = sep,
doi = {10.48550/arxiv.2609.02980},
eprint = {2609.02980},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2609.02980},
note = {CC BY-NC-ND 4.0},
}
RIS
TY - UNPB
TI - Homology Nilpotency in Rational Homotopy Theory: Cell Attachments, Retractive Towers, Divergence, and Stabilization
AU - Paul-Eugène Parent
PY - 2026
DA - 2026/09/02
PB - arXiv
DO - 10.48550/arxiv.2609.02980
UR - https://arxiv.org/abs/2609.02980
AB - Homology nilpotency of a simply connected minimal Sullivan algebra M is the least integer n for which (M^+)^n+1 is contained in an acyclic differential ideal. We develop lower- and upper-bound criteria, including methods for rational cell attachments, and construct an explicit finite-type minimal Sullivan algebra M satisfying nil_h(M)=3<Hnil(M)=4. Complete strictly coordinated retractive towers identify the obstruction: they characterize homotopical nil-length while exposing the additional quotient defect measured by homology nilpotency. We then show that this rigid defect disappears after stabilization by degreewise finite wedges of simply connected rational spheres: Hnil_s(X)=cat_o(X) for every simply connected rational space X of finite type.
ER -