# Corner conditions Asymptotically anti de Sitter spacetimes are not globally hyperbolic, i.e. we cannot choose initial data on a spacetime surface and obtain the solutions for all time. In addition to initial data, we also need boundary data. The question is, can we choose any boundary data we want? It turns out that if we want the solution to be smooth, there exist an infinite number of conditions at the corner where the initial surface intersects the timelike boundary. In [[2019#Horowitz, Wang]], we review and investigate this, where implications in the context of gauge/gravity duality are also discussed. The corner conditions in fact determine all time derivatives of the boundary metric in terms of the initial data at $t=0$. Since all time derivatives are fixed, we will obtain the full boundary condition if we ask the the function to be analytic. This turns out to give surprising consequences, which is investigated in [[2020#Horowitz, Wang]]. <!-- ## Potential - [[Idea202208101250 FG and corner conditions]] -->