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Must a finitely presented nil algebra be nilpotent? (Ufnarovskij's question)

Claims Corollary 3.8: there is an infinite-dimensional finitely presented nonunital associative F2\mathbb F_2-algebra that is nil and Jacobson radical but not nilpotent; its unitization is finitely presented, algebraic and infinite-dimensional. This answers Ufnarovskij's nil question, Amitsur's radical question and the finite-presentation version of Kurosh's algebraic finiteness question negatively, over F2\mathbb F_2. Every matrix over its positive-degree ideal is nilpotent. It does NOT give examples over other fields or in characteristic zero, and nilpotence indices are unbounded.

Exact FrontierDelta

Prior state unknown→disproved

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Occurred: Sep 23, 2026

Delta type: SOURCE CLAIM

Assumptions: VibeMathed verification: unreviewed. Publication: announcement. AI contribution: ai-discovered. VibeMathed editorial classifications, scores, notes, relations, and dataset structure are CC BY 4.0. Source statements and linked content retain their own rights.

Canonical aliases: Must a finitely presented nil algebra be nilpotent? (Ufnarovskij's question) · Finitely presented nil algebras

Confidence: Not scored

Registry verification: unreviewed · announcement · candidate

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Companion: An infinite finitely presented residually finite 2-group evidence for this event

VibeMathed record: Must a finitely presented nil algebra be nilpotent? (Ufnarovskij's question) evidence for this event

Must a finitely presented nil algebra be nilpotent? (Ufnarovskij's question) parent of this event

Claims Corollary 3.8: there is an infinite-dimensional finitely presented nonunital associative F2\mathbb F_2-algebra that is nil and Jacobson radical but not nilpotent; its unitization is finitely presented, algebraic and infinite-dimensional. This answers Ufnarovskij's nil question, Amitsur's radical question and the finite-presentation version of Kurosh's algebraic finiteness question negatively, over F2\mathbb F_2. Every matrix over its positive-degree ideal is nilpotent. It does NOT give examples over other fields or in characteristic zero, and nilpotence indices are unbounded. parent of this event

The finitely presented Burnside problem: is every finitely presented periodic group finite? evidence for this event

Smoktunowicz (2008), The Jacobson radical of rings with nilpotent homogeneous elements evidence for this event

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