The Schwarzschild-anti-de Sitter metric is a static spherically symmetric metric tensor on a Lorentzian manifold solving
the vacuum Einstein equation with negative cosmological constant. For cosmological
constant its four-dimensional line element
is
where and
is the unit round metric on
. For
, the unique positive zero
of
bounds the static exterior and satisfies
The constant-time spatial metric approaches hyperbolic space at infinity. This mass-radius relation is the model expression in the hyperbolic Penrose inequality.