Algebraic zip data

Richard Pink, Torsten Wedhorn, Paul Ziegler

An algebraic zip datum is a tuple $\CZ := (G,P,Q,ϕ)$ consisting of a reductive group $G$ together with parabolic subgroups $P$ and $Q$ and an isogeny $\varphi :P/R_{u}P\to Q/R_{u}Q$. We…