§7 · Root · root: registry, redirects, synthesis · 2026-10-18T04:41:45Z
Theorem 7.4 · Verdict: Sakellaridis's theorem over \(\mathbb F_q(\!(t)\!)\); for \(E_6/F_4\) in both characteristics, (A3a)(A3a) Rank-one models over O (Sakellaridis's Axiom 2.2.1): for every Borel orbit Y of maximal rank and every simple root α, the O-scheme YP_α/R(P_α) is one of the four standard PGL2-spaces over O, with his scheme structure on Y, and YP_α is the closure of its generic fibre minus the closure of the generic boundary. included
proved audit: minor defect ★ key step
Proposition VI splits into four audited parts. (a) is the published characteristic-0 theorem. (b) is its characteristic-\(p\) form for symmetric varieties under (T1)–(T5)Hypotheses of the characteristic-p transfer for symmetric X over W(F_q): (T1) H split with connected fibres; (T2) X(E) = G(E)x0; (T3) τ detects integral points; (T4) the Cartan decomposition over the ramified fields F'_e; (T5) Sakellaridis's theorem over F'_e = Q_q(p^{1/e}), e ≫ 0.. (c) says that \(E_6/F_4\) satisfies every hypothesis in both characteristics, (A3a)(A3a) Rank-one models over O (Sakellaridis's Axiom 2.2.1): for every Borel orbit Y of maximal rank and every simple root α, the O-scheme YP_α/R(P_α) is one of the four standard PGL2-spaces over O, with his scheme structure on Y, and YP_α is the closure of its generic fibre minus the closure of the generic boundary. included. (d) is the criterion. With Proposition VII, (SG) fails for \(E_6/F_4\) over \(\mathbb F_q(\!(t)\!)\) and over every \(p\)-adic field.
Proposition VI (\(p\) odd).
- (a), characteristic 0. Theorem 8.0.2 under (A1)–(A5)Sakellaridis's standing assumptions for Theorem 8.0.2: (A1) characteristic-0 field and split group; (A2) integral model; (A3a) rank-one models over O, (A3b) Cartan decomposition, (A3c) Iwahori orbits (his Axioms 2.2.1, 2.4.1, 2.4.2); (A4) spherical roots and colours; (A5) homogeneous, affine, one open Borel orbit., cited. For ramified \(F\) the normalizations are checked (Audit 4.7, Audit 5.5), and [Sa08] holds over every field of characteristic 0 (Audit 7.3).
- (b), characteristic \(p\). For a symmetric \(X\) over \(W(\mathbb F_q)\) under (T1)–(T5)Hypotheses of the characteristic-p transfer for symmetric X over W(F_q): (T1) H split with connected fibres; (T2) X(E) = G(E)x0; (T3) τ detects integral points; (T4) the Cartan decomposition over the ramified fields F'_e; (T5) Sakellaridis's theorem over F'_e = Q_q(p^{1/e}), e ≫ 0.: \(K\backslash X(\mathbb F_q(\!(t)\!))\simeq\Lambda_S^+\) and \(C_K\simeq\mathbb C[\delta(X)^{1/2}A_X^*]^{W_X}\) with \(\varphi_0\mapsto1\) (Proposition 4.9, audited Audit 5.7). A second, direct form reruns the analytic half of the proof in characteristic \(p\). It needs (A2)(A2) Integral model: X quasi-affine over O, its open Borel orbit smooth and surjective over O with B-homogeneous special fibre; a G-eigenmeasure on X and a B-invariant measure on the open orbit (§1.7)., (A5)(A5) X homogeneous and affine, and the open Borel orbit has a single B(F)-orbit of F-points (§8)., (A3b)(A3b) Cartan decomposition (Sakellaridis's Axiom 2.4.1): the X-antidominant torus points represent every K-orbit on X(F), and points with distinct labels lie in distinct K-orbits., (A3c)(A3c) Iwahori orbits (Sakellaridis's Axiom 2.4.2): xJ ⊆ xB(O) for every X-antidominant torus point x., Statements 6.3.1 and 7.1.5 in characteristic \(p\), the cone condition and H1H1 · Sakellaridis's triangularity (7.5) for the actual Θ of X. Equivalent to (U): the virtual colours belonging to each simple spherical root sum to its coroot (S1-1).–H3H3 · No spherical root of type N. (Objection 5.20), and not (A3a)(A3a) Rank-one models over O (Sakellaridis's Axiom 2.2.1): for every Borel orbit Y of maximal rank and every simple root α, the O-scheme YP_α/R(P_α) is one of the four standard PGL2-spaces over O, with his scheme structure on Y, and YP_α is the closure of its generic fibre minus the closure of the generic boundary..
- (c), \(E_6/F_4\). (A3a)(A3a) Rank-one models over O (Sakellaridis's Axiom 2.2.1): for every Borel orbit Y of maximal rank and every simple root α, the O-scheme YP_α/R(P_α) is one of the four standard PGL2-spaces over O, with his scheme structure on Y, and YP_α is the closure of its generic fibre minus the closure of the generic boundary. holds over every discrete valuation ring with 2 invertible (Theorem 2.8, audited Summary 6.9). The other hypotheses hold over \(\mathbb F_q(\!(t)\!)\) (Summary 3.12, audited Summary 5.13) and over \(p\)-adic fields (S4, S4b). So (T1)–(T5)Hypotheses of the characteristic-p transfer for symmetric X over W(F_q): (T1) H split with connected fibres; (T2) X(E) = G(E)x0; (T3) τ detects integral points; (T4) the Cartan decomposition over the ramified fields F'_e; (T5) Sakellaridis's theorem over F'_e = Q_q(p^{1/e}), e ≫ 0. hold.
- (d), the criterion. For \(E_6/F_4\), over \(\mathbb F_q(\!(t)\!)\) (Theorem 4.8, audited Audit 5.6) and over every \(p\)-adic \(F\): \(\mathcal H_K\varphi_0=C_K\) iff \(r\) is onto. Since \(r\) is not onto (Proposition VII), \(C_K=\mathcal H_K\varphi_0\oplus\mathbb C\,\mathbf 1_{Kx_{3\omega_1^\vee}}\). The direct route reaches the same conclusion, with Statement 6.3.1 in characteristic \(p\) supplied by (A3a)(A3a) Rank-one models over O (Sakellaridis's Axiom 2.2.1): for every Borel orbit Y of maximal rank and every simple root α, the O-scheme YP_α/R(P_α) is one of the four standard PGL2-spaces over O, with his scheme structure on Y, and YP_α is the closure of its generic fibre minus the closure of the generic boundary. (Audit 5.19, Summary 5.21).
Findings beyond the question. On p. 62 Sakellaridis derives (7.5) from \(|\Theta^+|-w|\Theta^+|=\check\rho-w\check\rho\). That identity is false by a factor 2 when \(\Theta^+=\check\Phi_X^+\) (Computation 1.7, Audit 5.17; checked by the root). (7.5) still holds when \(\Theta^+\subseteq\check\Phi_X^+\) has no repeated coroot, which covers \(E_6/F_4\). Chen–Yi prove their Prop. 17(i), the pages' input D0D0 · Orbit geometry over F̄_q, p ≠ 2 (Chen–Yi, Prop. 17, Thm 18): orbits indexed by Λ_S^+, closures, the support bound and the stabilizers., by citing results over \(\mathbb C\) (Audit 3.1, Audit 4.3, Audit 5.7).
Open. For a general symmetric \(X\) without the transfer: H1H1 · Sakellaridis's triangularity (7.5) for the actual Θ of X. Equivalent to (U): the virtual colours belonging to each simple spherical root sum to its coroot (S1-1).–H3H3 · No spherical root of type N., and Sakellaridis's Theorem 6.3.2 in characteristic \(p\). The audit pass (/solve-maths-audit) has not been run.
Builds on
- Theorem 2.8 · Theorem: Axiom 2.2.1Sakellaridis's Axiom 2.2.1, relabelled (A3a): rank-one models over O. holds for \(\mathcal M_\theta\) over every DVR with \(2\) invertible
- Summary 6.9 · Verdict: (A3a)(A3a) Rank-one models over O (Sakellaridis's Axiom 2.2.1): for every Borel orbit Y of maximal rank and every simple root α, the O-scheme YP_α/R(P_α) is one of the four standard PGL2-spaces over O, with his scheme structure on Y, and YP_α is the closure of its generic fibre minus the closure of the generic boundary. holds for \(\mathcal M_\theta\) over every DVR with \(2\) invertible
- Summary 3.12 · (Q3) verdict: (A1)(A1) Field and group: F a non-archimedean local field of characteristic 0 (Sakellaridis §1.1), G split reductive over O with connected fibres and simply connected derived group (§1.7).–(A3c)(A3c) Iwahori orbits (Sakellaridis's Axiom 2.4.2): xJ ⊆ xB(O) for every X-antidominant torus point x., (A5)(A5) X homogeneous and affine, and the open Borel orbit has a single B(F)-orbit of F-points (§8)., (A4)(A4) Spherical roots and colours: no pair of maximal rank of type N; classical Levis L_γ; Statements 6.3.1 and 7.1.5.(i,ii,iv) hold over \(\mathbb F_q((t))\)
- Summary 5.13 · Verdict of audit A5: transfer route A4-2…A4-9 and char-p hypotheses A3-1…A3-10
- Theorem 4.8 · Theorem: Theorem 8.0.2 for \(\mathcal M_\theta\) over \(\mathbb F_q((t))\); (SG) fails
- Proposition 4.9 · Proposition: what the characteristic-\(p\) theorem needs for symmetric \(X\)
- Audit 5.6 · Audit of A4-8: Theorem 8.0.2 for M_θ over F_q((t)); uniqueness; (SG)
- Audit 5.7 · Audit of A4-3 (τ closed immersion) and A4-9 (general symmetric X)
- Audit 7.3 · Check: Sakellaridis's 2008 paper is stated for every local field of characteristic \(0\)
- Objection 5.20 · Audit of A1-9: the characteristic-p Theorem 8.0.2 and its hypotheses
- Summary 5.21 · Verdict of the second audit: A1-1 … A1-9 (direct rerun over F_q((t)))
Built on by
- Summary S1.6 · Verdict inputs A5-20 and A5-21 re-derived; how R-4(b) and its open items read
- Summary 7.5 · Verdict after the audit: unchanged for \(E_6/F_4\); the general direct form completed