Freund-Rubin compactification
= Freund-Rubin compactification
{c}
{title2=$F_4=f\,\operatorname{vol}(\mathrm{AdS}_4)$}
A product compactification supported by a four-form proportional to one factor's volume form. For the maximally supersymmetric membrane throat, the other factor is a round $S^7$ and the radii obey $R_{S^7}=2R_{\rm AdS}$. The flux links the curvature scales through the supergravity field equations.