  A long-standing and intriguing question is: does the holographic principle
apply to cosmologies like de Sitter spacetime? In this work, we consider a half
dS spacetime wherein a timelike boundary encloses the bulk spacetime,
presenting a version of de Sitter holography. By analyzing the holographic
entanglement entropy in this space and comparing it with that in AdS/CFT, we
argue that gravity on a half dS$_{d+1}$ is dual to a highly non-local field
theory residing on dS$_d$ boundary. This non-locality induces a breach in the
subadditivity of holographic entanglement entropy. Remarkably, this observation
can be linked to another argument that time slices in global de Sitter space
overestimate the degrees of freedom by redundantly counting the same Hilbert
space multiple times.
