>What differentiates GR and 'mathematical GR'? Mathematical GR seeks to rigorously derive mathematical properties of the equations underlying GR, such as the e

>What differentiates GR and 'mathematical GR'? Mathematical GR seeks to rigorously derive mathematical properties of the equations underlying GR, such as the existence, stability, and long-range asymptotics of their solutions. It's largely a subfield of branch of math called "nonlinear wave equations".