Dual layering of compact abelian group actions

Prove that if a compact group $K$ acting on a compact abelian group $G$ is compactly layered by a decreasing chain of subgroups $(G_n)$, then the dual action of $K$ on the Pontryagin dual group $\widehat{G}$ is discretely layered by the subgroups $F_n=\widehat{G_n}$.

Background

The paper proves the asserted correspondence for the action of GLd(R)GL_d(R) on RdR^d, where the compact action is layered by the subgroups MdnM_d^n. It then seeks a general result relating compact layerings to discrete layerings under Pontryagin duality. A partial proof reduces the issue to showing that a certain induced action on the first dual layer is transitive, but the final step is explicitly stated to remain unresolved.

References

We present below a partial proof of this result, though the final step currently remains unsolved (and is a rather interesting problem in its own right).

— The Fourier Algebra of Certain Compact Orbit Hypergroups  (2609.35740 - Vujičić, 28 Sep 2026) in Conjecture labeled \textup{\textup{\textup{\textup{Conjecture}}}} in Section 4, “On the duality of layerings”