# Question about math notation closed as off-topic

The question "What is sigma function in the YOLO object detector?" has been closed as off-topic with the usual explanation:

This question appears to be off-topic because EITHER it is not about statistics, machine learning, data analysis, data mining, or data visualization, OR it focuses on programming, debugging, or performing routine operations within a statistical computing platform. If the latter, you could try the support links we maintain.

However, I think it does not really fit this description:

• It is arguably about machine learning.
• It is not about debugging neither performing routine operations within a statistical platform.

It clearly asks for explanation of mathematical notation used in one particular paper. It has even got two answers (one being accepted) before being closed. For the OP, it makes no difference whether it stays closed or not, but for any future visitors, it sends a message that "we don't want such questions here". In my opinion, it is not the case—except for using a screenshot instead of writing down the equations, it is an on-topic and answerable question.

Before I vote to reopen, I would like to know if I may have overlooked any other reason for off-topicness of this particular question.

• I agree with this action. But the post doesn't strike me as being a very good question, a quite different issue. It seems that the original authors didn't define their notation but my guess is that they would regard what they used as standard in their field. More directly put, would we be happy with posts asking for definitions of $\pi$ or $\exp()$ because authors didn't explain them? Are we here to teach people the little bits of mathematics they should be finding out any way, e.g. by reading simpler papers, textbooks, Wikipedia? – Nick Cox Apr 29 '19 at 15:18
• @NickCox, under the assumption that that happens, we would have $1$ question asking what $\pi$ is & $1$ question asking what $\exp$ is (all subsequent Qs should end up marked as duplicates). Personally, I would be fine with that. We don't have a lower bound on questions that are 'too trivial' & thus off topic for that reason. (OTOH, downvoting is fine for Qs that you believe 'lack research effort'). – gung - Reinstate Monica Apr 29 '19 at 15:22
• Though if a $\pi$ question pointed at something which actually said, for example, "the prior density $\pi_0(\theta)$", it might not be the same question as a question asking about the $\pi$ in "the density $\dfrac{1}{\sqrt{2 \pi} \sigma}\exp\left(-\dfrac{(x-\mu)^2}{2\sigma^2}\right)$" – Henry May 4 '19 at 1:16