Existence of non-strongly p-artinian groups and non-LFS-realizable fusion systems

From papers

A group is pp'-reduced if it has no nontrivial normal pp'-subgroups. A locally finite group is pp-artinian if it satisfies the relevant descending-chain condition, and it is strongly pp-artinian when it also satisfies the additional centralizer condition specified in the paper. A fusion system is LF-realizable if it is realized by a locally finite group, and LFS-realizable if it is realized by a locally finite, strongly pp-artinian group.

Existence conjecture. There are pp'-reduced locally finite pp-artinian groups that are not locally finite, strongly pp-artinian groups, and there are fusion systems that are LF-realizable but not LFS-realizable.

The conjecture proposes that both separations occur: the class of locally finite pp-artinian groups is strictly broader than the class of locally finite, strongly pp-artinian groups, and LF-realizability is strictly broader than LFS-realizability. The source states that no such examples are known and that constructing them appears difficult.

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Sources & referencesView supporting material

Primary source

Carles Broto, Ran Levi and Bob Oliver, “Realizability of fusion systems by discrete groups: II”, arXiv:2505.16375 (2025).

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