Agent 2 · launched 02:03 · returned 02:52 · 9 steps

Agent 2 · SL₂/SO₂: central inertia

The agent was asked to decide the categorical statement for \(X=\mathrm{SL}_2/\mathrm{SO}_2\), \(G=\mathrm{SL}_2\), a row the pages left open because both conditions of their Proposition III fail. It first computed the arc-group stabilizers: away from the base orbit each is \(\{\pm I\}\) times a connected pro-unipotent group, so the component group comes from the central element \(-I\) (Computation 2.1).

Because \(-I\) is central and acts trivially on the loop space, it acts on every equivariant sheaf by a natural involution \(\varepsilon\), which splits the category into an even and an odd part. The base sheaf and all Hecke kernels are even, and convolution multiplies \(\varepsilon\), so every Satake object is even (Lemma 2.3). The sign local system on the first orbit is odd, hence not generated (Theorem 2.4). The argument is topological, over \(\mathbb C\): no weights, no decomposition theorem, no transfer from finite fields. Since the convolution maps are finite and birational, each Satake object is a single IC sheaf, which gives the exact Satake span: the IC sheaves of the even orbits with constant coefficients (Proposition 2.7). At function level the \(\mathrm{SL}_2\) Hecke algebra is generated by the distance-two operator on the tree, and a dimension count shows that spherical generation fails for every \(q\), not only for \(q\) odd (Computation 2.8).

The audit found everything correct, with two small gaps: closure of the even part under cofibres needs one extra line, and a closing trace identification used a characteristic-0 lemma without comment (it still holds). The result is Theorem 1 of the verdict, and the only sheaf-level decision proved directly in the Betti category.

All 9 steps, in order
Result as the agent reported it proved

For X = SL_2/SO_2 with G = SL_2 over k = C: C^Sat is a proper thick subcategory of C. Precisely, the central element -I of SL_2(O) acts trivially on LX and defines a natural involution eps of the identity of C; C = C^+ ⊕ C^- by its eigenvalue, C^+ is thick and equals Shv_cons(L^+PGL_2 \ LX) via the mu_2-gerbe; every Satake object V_lambda * IC_0 lies in C^+ (convolution is bimultiplicative for eps and all Hecke objects and IC_0 are even), while the sign local system L_m^- on O_m (m >= 1; Stab(x_m) = mu_2 × t^m O, pi_0 generated by -I) gives nonzero objects of C^-. Moreover V_{n alpha^vee} * IC_0 ≅ IC(closure of O_{2n}) (the convolution map is finite and an isomorphism over the open orbit), so C^Sat = Thick{IC(O_{2n}, k)} ⊊ C^+ ⊊ C, with IC(O_1, k) ∉ C^Sat and IC(O_1, L_1^-) ∉ C^+. At function level (split form SL_2/T, any residue field F_q) (SG) fails for every q by a Hecke dimension count, and for q odd additionally by square classes (J(2)), whose sigma-parity is the Frobenius trace of eps; both levels fail and the sheaf argument is the geometric form of J(2).

Gap

none for C^Sat ≠ C (uses only the standing realisation of C with equivariant local systems = Rep(pi_0 Stab)); the exact description of C^Sat additionally uses the finite-length perverse heart on closed finite unions of orbits and finite-type slice models (Chen–Yi Lemma 45, Prop 47).

Blocked routes

Brief as sent

Target: \(X=\mathrm{SL}_2/\mathrm{SO}_2\), \(G=\mathrm{SL}_2\), where the pages leave the sheaf statement undecided (both conditions of Proposition III fail) and (SG) fails for \(q\) odd by square classes. Decide \(\mathcal C^{\mathrm{Sat}}=\mathcal C\) or \(\ne\) with a proof. Starting points: compute \(\operatorname{Stab}_{L^+\mathrm{SL}_2}(x_\mu)\) exactly and its component group; the simple equivariant perverse sheaves on \(\mathcal O_\mu\); what extra structure every Satake object carries (elements acting trivially on \(LX\) and on the Grassmannian; a larger group extending the action); whether a thick subcategory can be separated by such a structure; relate the \(\mathbb F_q\)-points of \(\mathcal O_\mu\) (Lang) to the square classes. State whether the two levels agree for this \(X\). Shared setting and rules: the problem card of the hub.

Scripts · computations this agent ran, kept with the run