Rigidity of joinings for time-changes of unipotent flows on quotients of Lorentz groups

Siyuan Tang

Let $u_X^t$ be a unipotent flow on $X=SO(n,1)/\Gamma$, $u_Y^t$ be a unipotent flow on $Y=G/{\Gamma }^{\prime }$. Let ${\tilde{u}}_X^t$, ${\tilde{u}}_Y^t$ be time-changes of $u_{X}^{t…