Abelian defect group cohomology conjecture for Deligne–Lusztig varieties

Let Xwφ\mathbf X_{\mathbf w\boldsymbol\varphi} be the relevant Deligne–Lusztig variety for GF\mathbf G^F, and define

Hcodd=ioddHci(Xwφ,Q),Hceven=ievenHci(Xwφ,Q).H_c^{\mathrm{odd}}=\bigoplus_{i\,\mathrm{odd}}H_c^i(\mathbf X_{\mathbf w\boldsymbol\varphi},\overline{\mathbb Q}_\ell),\qquad H_c^{\mathrm{even}}=\bigoplus_{i\,\mathrm{even}}H_c^i(\mathbf X_{\mathbf w\boldsymbol\varphi},\overline{\mathbb Q}_\ell).

Abelian defect group cohomology conjecture. The two GF\mathbf G^F-modules HcoddH_c^{\mathrm{odd}} and HcevenH_c^{\mathrm{even}} are disjoint, and FδF^\delta is semisimple on Hci(Xwφ,Q)H_c^i(\mathbf X_{\mathbf w\boldsymbol\varphi},\overline{\mathbb Q}_\ell) for every i0i\geq 0.

These are presented as special cases of abelian defect group conjectures for finite reductive groups. The source does not state a general resolution.

Sources & referencesView supporting material

Primary source

Michel Broué, Gunter Malle and Jean Michel, “Split Spetses for primitive reflection groups”, arXiv:1204.5846 (2012).

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