Considering a set $\mathcal S$ of events and given the values of intervals $s^2[~P, Q~] \in \mathbb R$
for all pairs of events $P, Q \in \mathcal S$ (up to a common non-zero scale factor):
how can conditions be expressed for whether $\mathcal S$ is "isotropic"?,
and in particular:
such that these conditions are equivalent to the definition of an isotropic manifold
in case that set $\mathcal S$ constitutes a manifold.
