§5 · Agent 5 · Functions without (A1)–(A5) · 2026-10-17T03:32:17Z
Theorem 5.7 · \((\mathrm{SG})\) for \(\GL_{2m}/\Sp_{2m}\) (all \(m\)) and \(\SL_{2n}/\Sp_{2n}\) (all \(n\)), every non-archimedean local field
proved audit: minor defect ★ key step
A downward induction in finite slices of fixed degree, using the triangular rows of Lemma 5.6 and central shifts, puts every orbit indicator in the Hecke span of the basic function; restricting to Pfaffian valuation zero gives the \(\SL\) case. This replaces 'holds under (A)“Under (A)”: assuming all of Sakellaridis's assumptions (A1)–(A5) for X at the given p-adic place, so that his Theorem 8.0.2 applies.' by 'holds' for both rows of Table 1, with no dominant lifts, no Theorem E and no (A1)–(A5)Sakellaridis's standing assumptions for his Theorem 8.0.2 (the pages' Theorem E): (A1) a characteristic-0 field and a split group with simply connected derived group; (A2) an integral model of X with a smooth open Borel orbit and invariant measures; (A3a) rank-one models over O, (A3b) the Cartan decomposition, (A3c) Iwahori orbits (his Axioms 2.2.1, 2.4.1, 2.4.2); (A4) conditions on the spherical roots and colours; (A5) X homogeneous and affine with one open Borel orbit..
Theorem 5.7.
Theorem. \(\cH_K\cdot\varphi_0=C_K\) for \(X=\GL_{2m}/\Sp_{2m}\), every \(m\ge1\), and every non-archimedean local field \(F\).
Corollary. \((\mathrm{SG})\) holds for \(\SL_{2n}/\Sp_{2n}\), every \(n\), every \(F\).
Proof of the theorem.
- Orbits. By the symplectic Smith form, \(K\backslash X(F)\leftrightarrow\{b\in\Z^m:b_1\ge\dots\ge b_m\}\); the orbits are compact open and their indicators span \(C_K\).
- Slices. For \(d,c\in\Z\) the set \(S_{d,c}:=\{b:\ b_m\ge2c,\ |b|=d\}\) is finite, and every label \(b\) lies in \(S_{|b|,\lfloor b_m/2\rfloor}\).
- Triangular translates. For \(b\in S_{d,c}\) put \(f_b:=T_{(c,\dots,c)}\ast T_{\lambda^*(b-2c\mathbf 1)}\). By the central shift of Computation 5.5 and Lemmas 2 and 3 of Lemma 5.6,
- Induction. Descending induction on \(\ge_{\mathrm{dom}}\) in the finite poset \(S_{d,c}\) — Proposition B with the order \(b'\preceq b\iff b'\ge_{\mathrm{dom}}b\), restricted to \(S_{d,c}\) — gives \(\one_{O_b}\in\cH_K\cdot\varphi_0\) for every \(b\). \(\square\)
Proof of the corollary. The degree-zero reduction in the last part of Proposition F is re-verified without hypotheses. \(X_{\SL}(F)=\{\Pf=1\}\) is a single \(\SL_{2n}(F)\)-orbit (a symplectic basis and \(\Pf(gJg^{\mathsf T})=\det g\)); \(O_b\cap X_{\SL}(F)\) is a single \(K_{\SL}\)-orbit; the coset spaces \(Kt^\lambda K/K\) and \(K_{\SL}t^\lambda K_{\SL}/K_{\SL}\) correspond bijectively when \(|\lambda|=0\) (adjust by \(\operatorname{diag}(u,1,\dots,1)\)); and \(T_\lambda\ast\varphi_0\) is supported on \(\val\Pf=|\lambda|\). So the degree-zero part of \((\mathrm{SG})\) for \(\GL_{2n}\) is \((\mathrm{SG})\) for \(\SL_{2n}\). \(\square\)
Consistency. \(m=1\) is Proposition J(3); \(m=2\) is Computation 5.5; \(\SL_4/\Sp_4\cong\Spin_6/\Spin_5\) agrees with Theorem 5.3.
Mechanism versus coverage. For an uncovered label \(b\) (some \(b_i=b_{i+1}\) odd) the row used is \(\lambda^*(b)\), whose top orbit \(\varphi(\lambda^*(b))=(b_1+b_2,b_1+b_2,b_3+b_4,\dots)\) lies strictly above \(b\): the induction runs downward from the top of \(S_{d,c}\) instead of upward from dominant lifts. Nothing from Theorem E or (A1)–(A5)Sakellaridis's standing assumptions for his Theorem 8.0.2 (the pages' Theorem E): (A1) a characteristic-0 field and a split group with simply connected derived group; (A2) an integral model of X with a smooth open Borel orbit and invariant measures; (A3a) rank-one models over O, (A3b) the Cartan decomposition, (A3c) Iwahori orbits (his Axioms 2.2.1, 2.4.1, 2.4.2); (A4) conditions on the spherical roots and colours; (A5) X homogeneous and affine with one open Borel orbit. is used, and \(\operatorname{char}F\) and \(q\) are arbitrary.
Builds on
- Lemma 5.6 · \(\GL_{2m}/\Sp_{2m}\): the rows \(\lambda^*(b)=(b,0)\) are triangular for reverse dominance
- Computation 5.5 · \(\GL_4/\Sp_4\): lattice counts and a Hecke element for the uncovered label \((1,1)\)
Built on by
- Summary 5.10 · Table changes at function level; no row disagrees between the levels; nothing here depends on (A)“Under (A)”: assuming all of Sakellaridis's assumptions (A1)–(A5) for X at the given p-adic place, so that his Theorem 8.0.2 applies.
- Dead end 5.9 · \(E_6/F_4\) at function level: what the lattice method would need
- Audit 7.23 · Audit of the \(\GL_{2m}/\Sp_{2m}\) theorem: the induction holds (directly, not through Proposition B as stated); the \(\SL\) corollary and the sheaf consequence hold
- Re-derivation X1.5 · (SG) for GL₂ₘ/Sp₂ₘ re-derived from Lemmas 2–3 alone; A4-13's open cells now decided
- Summary X3.7 · A7-25, A7-32 re-derived; the \(\mathrm{GL}_n/(\mathrm{GL}_p\times\mathrm{GL}_q)\) row
- Audit 9.3 · Registry after the lattice-count audit: every row except \(E_6/F_4\) decided at both levels; the \(E_6\) Weyl conjugacy re-checked
- Summary 9.4 · Synthesis: \(E_6/F_4\) is the one divergence (categorical generation holds, functions fail under (A)“Under (A)”: assuming all of Sakellaridis's assumptions (A1)–(A5) for X at the given p-adic place, so that his Theorem 8.0.2 applies.); no reverse case
Original record, as the agent wrote it at 03:32 UTC
(SG) for GL_{2m}/Sp_{2m} (all m) and SL_{2n}/Sp_{2n} (all n), every local field F
Theorem. \(\mathcal H_K\cdot\varphi_0=C_K\) for \(X=\mathrm{GL}_{2m}/\mathrm{Sp}_{2m}\), every \(m\ge1\), every non-archimedean local field \(F\). Proof. 1. Orbits: \(K\backslash X(F)\leftrightarrow\{b\in\mathbb Z^m:b_1\ge\dots\ge b_m\}\) (symplectic Smith form), compact open, indicators span \(C_K\).
- Fix \(d\in\mathbb Z\), \(c\in\mathbb Z\); \(S_{d,c}:=\{b:\ b_m\ge2c,\ |b|=d\}\) is finite. Every label lies in some \(S_{|b|,\lfloor b_m/2\rfloor}\).
- For \(b\in S_{d,c}\) put \(f_b:=T_{(c,\dots,c)}\ast T_{\lambda^*(b-2c\mathbf 1)}\). By node 5 (central shift) and node 6, Lemmas 2–3,
- Descending induction on \(\ge_{\mathrm{dom}}\) in the finite poset \(S_{d,c}\) (Proposition B with the order "\(b'\preceq b\iff b'\ge_{\mathrm{dom}}b\)" restricted to \(S_{d,c}\)): \(\mathbf 1_{O_b}\in\mathcal H_K\cdot\varphi_0\) for all \(b\). \(\square\)
Corollary. (SG) for \(\mathrm{SL}_{2n}/\mathrm{Sp}_{2n}\), every \(n\), every \(F\): the degree-\(0\) reduction of classical.html (Prop. F, last part) is re-verified without hypotheses: \(X_{\mathrm{SL}}(F)=\{\mathrm{Pf}=1\}\) is one \(\mathrm{SL}_{2n}(F)\)-orbit (symplectic basis + \(\mathrm{Pf}(gJg^{\mathsf T})=\det g\)), \(O_b\cap X_{\mathrm{SL}}(F)\) is one \(K_{\mathrm{SL}}\)-orbit, \(Kt^\lambda K/K\to K_{\mathrm{SL}}t^\lambda K_{\mathrm{SL}}/K_{\mathrm{SL}}\) is bijective for \(|\lambda|=0\) (adjust by \(\mathrm{diag}(u,1,\dots)\)), \(T_\lambda\ast\varphi_0\) lives on \(\operatorname{val}\mathrm{Pf}=|\lambda|\), so the degree-\(0\) part of (SG) for \(\mathrm{GL}_{2n}\) is (SG) for \(\mathrm{SL}_{2n}\).
Consistency: \(m=1\) is Prop. J(3); \(m=2\) is node 5; \(\mathrm{SL}_4/\mathrm{Sp}_4\cong\mathrm{Spin}_6/\mathrm{Spin}_5\) agrees with node 3.
Mechanism vs. coverage: for an uncovered \(b\) (some \(b_i=b_{i+1}\) odd) the row used is \(\lambda^*(b)\), whose top orbit \(\varphi(\lambda^*(b))=(b_1+b_2,b_1+b_2,b_3+b_4,\dots)\) lies strictly above \(b\); the induction runs downward from the top of \(S_{d,c}\) instead of upward from dominant lifts. Nothing from Theorem E or (A1)–(A5) is used; \(\operatorname{char}F\) and \(q\) are arbitrary.
Sources
- classical.html#Proposition F
- classical.html#Proposition B