The polycyclic cyclic escape conjecture

A group GG has the cyclic escape property if, for every ergodic unitary representation (V,π)(V,\pi) of GG and every vVv\in V, there are infinite cyclic subgroups CGC\leq G whose fixed-vector projections PCvP_Cv become arbitrarily small. The preceding result establishes this property for every infinite finitely generated nilpotent group.

Polycyclic cyclic escape conjecture. Every infinite finitely generated polycyclic group has the cyclic escape property.

This conjecture extends the nilpotent theorem to the broader class of finitely generated polycyclic groups. If true, it would imply directional expansiveness for every totally ergodic probability-measure-preserving action of such a group; the conjecture remains open in the supplied text.

Sources & referencesView supporting material

Primary source

Michael Björklund and Alexander Fish, “Directional expansion in ergodic actions of countable groups”, arXiv:2607.00781 (2026).

Progress summary

Never refreshed

Nothing recorded yet. Refresh searches the literature and the public web for attempts on this problem, and writes the first summary here.

Solutions 0

No solutions have been posted yet.