Transitivity and an abelian Livsic theorem for covers
Mark Pollicott, Richard Sharp
TL;DR
This paper extends the abelian Livšic theorem to the setting where the lifted flow on a regular cover is transitive, showing that zero-periodic-integral data on Frobenius-trivial orbits suffices to express the cocycle as a coboundary plus a closed 1-form. The authors adapt the argument to subshifts of finite type, then transfer it to transitive Anosov flows, providing a sharp criterion that requires no extra covering-group conditions. They apply the result to marked length spectrum rigidity, establishing rigidity from data on non-universal covers, and extend the methodology to cocycles valued in connected Lie groups under a distortion hypothesis, revealing a central-obstruction decomposition. Collectively, the work broadens the reach of Livšic-type rigidity to covers and non-abelian contexts, with concrete geometric implications.
Abstract
We show that the abelian Livšic theorem recently obtained by A. Gogolev and F. Rodriguez Hertz for null-homologous periodic orbits of homologically full Anosov flows continues to hold when restricted to periodic orbits which are trivial with respect to any regular cover for which the lifted flow is transitive.
