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Morita equivalent blocks with an endotrivial source that are not globally isotypic
Abstract
Let (K,πͺ,k) be a large enough $2$-modular system. We construct two nilpotent block algebras of finite groups which are isomorphic as πͺ-algebras and are Morita equivalent via a bimodule with an endotrivial source of πͺ-rank $3$, but which are not globally isotypic. Hence they are not $2$-permutation equivalent and not splendidly Rickard equivalent. These results separate Morita equivalences with endopermutation source from p-permutation equivalences and splendid Rickard equivalences, and also separate almost global isotypies from global isotypies.
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BibTeX
@misc{huang2026morita,
title = {{Morita equivalent blocks with an endotrivial source that are not globally isotypic}},
author = {Xin Huang},
howpublished = {arXiv},
year = {2026},
month = oct,
doi = {10.48550/arxiv.2608.31083},
eprint = {2608.31083},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2608.31083},
}
RIS
TY - UNPB
TI - Morita equivalent blocks with an endotrivial source that are not globally isotypic
AU - Xin Huang
PY - 2026
DA - 2026/10/19
PB - arXiv
DO - 10.48550/arxiv.2608.31083
UR - https://arxiv.org/abs/2608.31083
AB - Let (K,πͺ,k) be a large enough $2$-modular system. We construct two nilpotent block algebras of finite groups which are isomorphic as πͺ-algebras and are Morita equivalent via a bimodule with an endotrivial source of πͺ-rank $3$, but which are not globally isotypic. Hence they are not $2$-permutation equivalent and not splendidly Rickard equivalent. These results separate Morita equivalences with endopermutation source from p-permutation equivalences and splendid Rickard equivalences, and also separate almost global isotypies from global isotypies.
ER -