Abelianness and strict A1-invariance of connected components of reductive groups
Abelianness and strict A1-invariance of connected components of reductive groups
Let be a field and let be a reductive algebraic group over . Write for the sheaf of -connected components of . A sheaf of groups is strictly -invariant if it is a sheaf of abelian groups and its Nisnevich cohomology presheaves are -invariant in every degree.
Abelianness and strict invariance conjecture. For every reductive group over , the sheaf is a sheaf of abelian groups. Moreover, is strictly -invariant.
This would place the -connected components of every reductive group in the abelian category of strictly -invariant sheaves. The abelianness of these sheaves is stated as an open question in the source, and strict -invariance would then follow from the relevant -homotopy-theoretic results; no general proof is given here.
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Sources & referencesView supporting material
Primary source
Amit Hogadi and Anand Sawant, “Transfers on A^1-connected components of quasi-split groups and the norm principle”, arXiv:2512.15324 (2025).
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