In conclusion, GR is a fundamental theory of gravity...
where $\Gamma_{ij}$ are the Christoffel symbols, which describe the connection between nearby points in spacetime. the theoretical minimum general relativity pdf
$$R_{ijkl} = \partial_i \Gamma_{jk} - \partial_j \Gamma_{ik} + \Gamma_{im} \Gamma_{jk}^m - \Gamma_{jm} \Gamma_{ik}^m$$ In conclusion, GR is a fundamental theory of gravity