# GR as a gauge theory

There is no such thing as an a-posterior assumption. If something follows from you assumptions it is a consequence not an assumption.
lol, can't you recognize a joke?

PAllen
2019 Award
Here is an interesting discussion about analyticity in physics, one of the answers, by unknown even refers to GR (in this case it makes reference to the no-hair theorem that is also valid only for real analytic manifolds).

http://mathoverflow.net/questions/114555/does-physics-need-non-analytic-smooth-functions
General theorems of this type typically do required a number of technical assumptions to prove anything. Such theorems don't assume anything about the metric, thus they typically need smoothness assumptions to constrain the problem enough to accomplish the proof.

Again, in the case of uniquness of KS geometry, such additional assumption is not needed because the existence and vanishing of the Einstein tensor everywhere is already requiring a sufficient degree of smoothness.

General theorems of this type typically do required a number of technical assumptions to prove anything. Such theorems don't assume anything about the metric, thus they typically need smoothness assumptions to constrain the problem enough to accomplish the proof.

Again, in the case of uniquness of KS geometry, such additional assumption is not needed because the existence and vanishing of the Einstein tensor everywhere is already requiring a sufficient degree of smoothness.
You are again conflating smoothness and analyticity.

PAllen