In reference to my question here: What would be essential math topics to read for general relativity (from a particular book)?
I'm reading a book and wanted to get a clear understanding on what topics from that book are essential as mathematical prerequisites for grad level general relativity. I searched before posting as is required, and found no other questions in the same spirit.
Either the answers therein are general book recommendations, e.g. here, or they give a broader idea about what math fields are involved (like "understanding of differential geometry", "abstract algebra topics like scalar product spaces", etc.) - see here. What I'm looking for is much more specific.
I was told that the question is a duplicate (I'm not convinced that it is) and later on that it's opinion-based - again, I'm not so sure because mathematical topics needed to tackle grad level GR doesn't sound like a subjective topic.
I'm hoping that members of the community experienced in GR could help out in that regard, and so it's important for me to have that question open. Could I get some feedback on how I can improve it?