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Record W2025104847 · doi:10.1112/s0024611500012338

Derivations on Group Algebras

2000· article· en· W2025104847 on OpenAlex

Why this work is in the frame

A frame that forgets how it found something cannot be audited. These are the routes that admitted this work.

affAt least one author lists a Canadian institution in the pinned OpenAlex snapshot.

Bibliographic record

VenueProceedings of the London Mathematical Society · 2000
Typearticle
Languageen
FieldMathematics
TopicAdvanced Topics in Algebra
Canadian institutionsUniversity of Manitoba
Fundersnot available
KeywordsMathematicsGroup (periodic table)Unimodular matrixHausdorff spaceElement (criminal law)CombinatoricsSubgroupConjugacy classGroup algebraGroup actionDiscrete groupPure mathematicsCohomologyNormal subgroupAlgebra over a field

Abstract

fetched live from OpenAlex

Let G be a locally compact group. The question of whether H1 L1(G),M(G), the first Hochschild cohomology group of L1(G) with coefficients in M(G), is zero was first studied by B. E. Johnson and initiated his development of the theory of amenable Banach algebras. He was able to show that H1(L1(G), M(G) = 0 whenever G is amenable, a [SIN]-group, or a matrix group satisfying certain conditions. No group such that H1(L1(G),M(G) ≠ 0 is known. In this paper, we approach the problem of whether H1(L1(G),M(G) = 0 from several angles. Using weakly almost periodic functions, we show that H1(L1(G),L1(G) is always Hausdorff for unimodular G. We also show that for [IN]-groups, every derivation D : L1(Gto L1(G is implemented, not necessarily by an element of M(G), but at least by an element of VN(G), the group von Neumann algebra of G. This applies, in particular, to the group G : = T2 ⋊ SL(2,Z}, for which it is unknown whether H}1(L1(G),M(G) = 0. Finally, we analyse the structure of derivations on L1(G); an important role is played by the closed normal subgroup N of G generated by the elements of G with relatively compact conjugacy classes. We can write an arbitrary derivation D : L1(G) to L1(G) as a sum D = DN DN⊥$, where DN and DN⊥ can be tackled with different techniques. Under suitable conditions, all satisfied by T2 ⋊ SL(2,Z}, we can show that DN is implemented by an element of VN(G) and that DN⊥ is implemented by a measure. 1991 Mathematics Subject Classification: 22D05, 22D25, 43A10, 43A20, 46H25, 46L10, 46M20, 47B47, 47B48.

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Full frame distilled prediction

Teacher imitation

Not calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.

metaresearch head score (Codex)0.000
metaresearch head score (Gemma)0.001
Version: codex-gemma-dda1882f352aValidation status: machine_predicted_unvalidated
Candidate categoriesInsufficient payload (model declined to judge)
Consensus categoriesnone
DomainCandidate signal: none · Consensus signal: none
Study designCandidate signal: Theoretical or conceptual · Consensus signal: Theoretical or conceptual
GenreCandidate signal: Empirical · Consensus signal: Empirical
Teacher disagreement score0.231
Threshold uncertainty score1.000

Codex and Gemma teacher scores by category

CategoryCodexGemma
Metaresearch0.0000.001
Meta-epidemiology (narrow)0.0000.000
Meta-epidemiology (broad)0.0000.000
Bibliometrics0.0000.000
Science and technology studies0.0000.000
Scholarly communication0.0000.000
Open science0.0010.000
Research integrity0.0000.000
Insufficient payload (model declined to judge)0.0010.000

Machine scores (provisional)

The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.

Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.

Opus teacher head0.028
GPT teacher head0.288
Teacher spread0.260 · how far apart the two teachers sit on this one work
Validation statusscore_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from it