Let $X$ be a scheme and let $X_{red}$ be its reduction (defined through its universal property). What is the functor of points of $X_{red}$? Put differently, which maps $\phi : \text{Spec }R \to X$ factor through the reduction of $X$? I am reading notes by Marc-Nieper Wißkirchen which claim that ...

I recently came across this post on always mentioning if a question is from a competition , and in the past, I've asked many questions that are from certain comeptitive exams in my country. However, these exams aren't explicitly for maths, so I'm not sure if I should have used that tag in the pa...

No it's not a contest question Firstly if your competitive exams are anything like the ones in my country then the exams are conducted offline and the same questions are not repeated between papers which batches of students write. So, there is no particular gain or loss in knowing the answer to t...

Yes, your question is a contest question because it is from a contest. Even if the contest is not explicitly about math, it is still a contest problem. You still need to disclose the source, explain that this is a general academic contest (or whatever the correct description is), and follow the r...

I thought it was put to prevent cheating in ongoing contests, but I am unable to figure out what utility it is of when put on questions from a contest, for which knowing answers in the present is inconsequential, is asked. Wouldn't it be enough if OP simply gave the source of the question? One pl...

I recently came across this post on always mentioning if a question is from a competition , and in the past, I've asked many questions that are from certain comeptitive exams in my country. However, these exams aren't explicitly for maths, so I'm not sure if I should have used that tag in the pa...