PreprintCC BY 4.0arXiv
On extensive amenability of algebras
Abstract
For a module M over a cocommutative Hopf algebra π, we define extensive amenability by amenability of its symmetric algebra as a module over Sym(M)#π. Using the author's coalgebraic rounding and quotient theorems, we prove that nonzero extensively amenable modules are amenable, that every module over an amenable Hopf algebra is extensively amenable, and that extensive amenability is preserved and reflected by short exact sequences. For permutation modules this definition agrees, over every field, with extensive amenability of group actions. A final section gives the modifications for exterior algebras and establishes the comparison between the two definitions in several cases.
Related
BibTeX
@misc{bartholdi2026extensive,
title = {{On extensive amenability of algebras}},
author = {Laurent Bartholdi},
howpublished = {arXiv},
year = {2026},
month = oct,
doi = {10.48550/arxiv.2610.00364},
eprint = {2610.00364},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2610.00364},
note = {CC BY 4.0},
}
RIS
TY - UNPB
TI - On extensive amenability of algebras
AU - Laurent Bartholdi
PY - 2026
DA - 2026/10/01
PB - arXiv
DO - 10.48550/arxiv.2610.00364
UR - https://arxiv.org/abs/2610.00364
AB - For a module M over a cocommutative Hopf algebra π, we define extensive amenability by amenability of its symmetric algebra as a module over Sym(M)#π. Using the author's coalgebraic rounding and quotient theorems, we prove that nonzero extensively amenable modules are amenable, that every module over an amenable Hopf algebra is extensively amenable, and that extensive amenability is preserved and reflected by short exact sequences. For permutation modules this definition agrees, over every field, with extensive amenability of group actions. A final section gives the modifications for exterior algebras and establishes the comparison between the two definitions in several cases.
ER -