@user170039 Thanks for pointing out this question. I looked at it & some of the answers. I found them interesting and agree with you that it shouldn't be deleted. As you can see, I also added a fairly long comment there explaining my position & reasoning for it.

@user170039 I am happy to see that question remain in its current state: closed, but not deleted. It is not really an appropriate question for MSE, but it is probably worth keeping around "for historical significance".

I'll also not that it is highly likely to be deleted, given the number of upvotes it has.

Any help making this clearer would be greatly appreciated: math.stackexchange.com/questions/3262004

The answer might be "where do I start?" If so, even where to start would be appreciated.

D1, D2, D3.

D4, D5, D6.

D7, D8, D9.

D10, D11, D12.

D13, D14, D15.

C4, C5, C6.