Geometric origin of invariant categories under finite group actions

Determine whether, for any smooth proper S-linear category C of geometric origin and any finite group G acting S-linearly on C, the invariant category C^G is itself of geometric origin. In particular, resolve this question in the case C = D(X) for a smooth proper S-scheme X.

Background

The paper studies actions of finite groups on smooth proper S-linear categories and investigates when the corresponding invariant categories arise from geometry. Although CG is always smooth and proper, its being of geometric origin (i.e., admitting a realization as a semiorthogonal component of D(Y) for a smooth proper S-scheme Y) is subtle.

The authors provide positive results by geometrizing many actions via gerbes and show that in these situations CG is of geometric origin. However, they point out that the general case is not settled even for the fundamental geometric example C = D(X).

References

In this setting, the invariant category CG is a smooth proper S-linear category [3, Proposition 3.15], but it is unknown whether CG is necessarily of geometric origin, even if C = D(X).

The semiregularity theorem for equivariant noncommutative varieties  (2604.00511 - Perry, 1 Apr 2026) in Section 4, Geometrizing group actions on derived categories (first paragraph)