§8 · Audit · Fresh review, re-checks · 2026-10-18T06:07:12Z

Review G1 · Review G1 · Agent 1

proved ★ key step

A fresh reviewer graded 9 steps of Agent 1: 1 error, 4 minor, 4 correct.

Review G1.

Strategy 1.1 (minor): I checked all 27 rows against arXiv:0905.4244v3 (where each input sits, page, what it is used for) and against the replacing nodes: the inventory is accurate and complete for the proof of Theorem 8.0.2 (Lemma 7.1.4 is row 22), and psi(x)=psi_0(Tr Res(x dt)) has conductor exactly O with dx(O)=1 self-dual. One misfiling: row 25 lists Lemma 4.2.3 as characteristic-free given (A3c)(A3c) Iwahori orbits (Sakellaridis's Axiom 2.4.2): xJ ⊆ xB(O) for every X-antidominant torus point x. and the invariant measure, but its proof (p. 27) needs the image of Phi_K to be finite at delta^{1/2}, taken from (4.5), i.e. [CS80]; this also contradicts row 17 ('not needed'). Nothing on the E6/F4 route depends on it, because Computation 1.7 computes c directly.

Lemma 1.4 (minor): I re-derived the argument. Y(F)/B(F)=ker(H^1(F,B_y)->H^1(F,B)) with H^1(F,B)=1. M_y is a closed subgroup of T, hence G_m^a x mu_2^b. Each twisted unipotent radical equals U_H(lambda) for a cocharacter of a split maximal F-torus that is positive on its weights, so it is F-split; I could not open CGP 2.1.10, but Milne, Algebraic Groups 22.86, states the same over any infinite field. Hence H^1(F,B_y) injects into (F^x/F^x2)^b, and |F^x/F^x2|=4. The filtration (orbits by decreasing dimension, each B(F)-orbit open and closed in Y(F)) is right. For (d) I computed (1+w_L)P=Z w1+Z w6, saturated in P, so T^theta is connected and X°(F)=x0B(F). Defect: step 5 justifies openness by 'the implicit function theorem over a complete non-discretely valued field', but F_q((t)) is discretely valued. The theorem actually needed holds over every complete non-trivially valued field, so this slip in the wording changes no claim.

Proposition 1.5 (minor): (a) re-derived: regular B-eigenfunctions (Lie-Kolchin for split B, X affine) confine lambda(x) on supp(phi) to a translate of the dual cone, so (3.2) converges absolutely when s(chi) lies in the interior of cone(eta_i). (b) re-derived: E_y is Zariski closed. E_y=D' would force T_y=(T^theta)° and theta''(beta)=theta(beta) on roots, and the theta-order then gives dim B_y<=dim T^theta+|Phi_L^+|=dim B_x0, so By would be open, a contradiction. With the Bernstein-Zelevinsky filtration this gives generic uniqueness. (c) Bernstein's principle applies on R cap D1', which is nonempty. Defect: step 7's 'both preserve a W-invariant inner product, so equal +1-eigenspaces force theta'_T=theta|_T' is unjustified when the central torus has rank >=2. What the count needs does hold: agreement on the coroot span, where both preserve the canonical form (hence agreement on roots), and dim T^theta'=dim T^theta, as Audit 5.14 says. Irrelevant for E6, which is semisimple.

Computation 1.7 (minor): I redid all numbers by different algorithms (scripts e6.py, e6b.py, a2check.py). |N_W(a)|=1152 from the 45 W-conjugates of the D4 subsystem. W_X'=<u1,u6> with u1=w0(D5)w_L (equal to the Brion word s1s3s4s2s5s4s3s1); it has order 6, and its six actions on (gamma1,gamma6) are exactly as listed. gamma1=2w1-w6, gamma6=-w1+2w6, <a_i^vee,rho_P(X)>=4. Exact checks passed for B_{w_gamma}=beta/(beta o w_gamma), sum_w 1/beta(w chi)=(1+q^-4)(1+q^-4+q^-8), (7.4) against the W-symmetrisation, W-invariance, weights in lambda+R, and nonzero leading coefficients for 25 antidominant lambda (q=3,5). The inversion-set proof of (7.5) and the factor-2 correction of p. 62 are right (in general |Theta+|-w|Theta+|=2|N_Theta(w^-1)|). Two defects change no claim. First, 'Lambda_X=Ze1+Ze6, <e_i,gamma_j> the Cartan matrix, e_i=gamma-check_i' is off by a factor 2 for e_i=(1-theta0)a_i^vee as in the setting (<e1,gamma1>=4, <e1,rho_P>=8, and the image of e_i in Lambda_X is 2[a_i^vee]); the computation uses the right gamma-check_i=[a_i^vee], and Theorem 3.8 handles this factor through phi=1-theta. Second, Lemma 4.2.3 is said to use only the invariant measure, but it uses (4.5); here it serves only as a consistency check.

Theorem 1.9 (error): The E6/F4 corollary holds: I re-derived it from Proposition 1.5, Proposition 1.6, Computation 1.7 (beta built directly from Phi_X^+, leading coefficients checked), Proposition 1.2 with sigma(lambda)=-w0 lambda, X(O)=Kx0 (Lang for F4 plus Hensel) and Proposition VII; it is conditional on (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)., (A3b'), (A3c)(A3c) Iwahori orbits (Sakellaridis's Axiom 2.4.2): xJ ⊆ xB(O) for every X-antidominant torus point x. and (S6.3.1)_p. The general symmetric theorem fails as written, in five places. (1) 'With (iii)_p and (iv)_p, Sakellaridis's proof of Theorem 7.2.1 gives B_w=beta/(beta o w)': that step also uses the uniqueness half of Lemma 7.1.4 (one colour per type-G root, a pair for type T), which is proved only by inspecting the characteristic-0 classification. Because D_V counts colours with multiplicity, two colours of valuation gamma-check satisfy 6.3.1 and 7.1.5 yet square the factor. So a characteristic-0 lemma is used in characteristic p, although the step claims both characteristic-0 places are kept as explicit hypotheses. (2) (7.5) is justified only by Computation 1.7's argument, which covers multiplicity-free Theta+ in Phi_X^+ only. (3) A1-4 and A1-5 are applied with F-rational adapted data that are neither assumed nor proved. (4) Non-vanishing of the leading coefficients (hypothesis (c) of Proposition 1.2, including c!=0, which is obtained 'by Lemma 4.2.3' although that lemma uses (4.5)) is not shown for general Theta. (5) 'No type N' is presupposed by (iii)_p. Objection 5.20's H1-H3 repair (1)-(3) and (5): 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). with T=cone(Theta+) also forces the colours of each simple root to be exactly those of 6.3.1. They do not repair (4), and A5-20's 'c!=0 follows from Omega_chi!=0' is a non sequitur for general X. conclusion_holds refers to the E6/F4 corollary, the part used downstream; the general statement is plausible but unproven.

Builds on

  • Theorem 1.9 · Theorem 8.0.2 over \(\mathbb F_q((t))\), \(p\) odd, symmetric \(X\): hypotheses

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