I received a down vote on this question without any comment.
Can one help me to understand how this question could be improved?
I think that a moral and implicit policy of MO is that a comment should be added to every down vote.
I received a down vote on this question without any comment.
Can one help me to understand how this question could be improved?
I think that a moral and implicit policy of MO is that a comment should be added to every down vote.
A way to improve the question could be to mention in which context it arose, and why you ask the specific questions you asked. Generally, it is encouraged to present some context with the question, and not only a terse question.
From a stylistic point of view, as written it looks like a textbook exercise. Questions presented in this style are often not well-received.
Let me make very clear that I have no idea how hard or interesting the question is in its substance, All I want to point out is that votes based on the criterion "looks like a homework problem" (based on the style, not the content) do happen.
Let me add some points to quid's nice answer on how to manage the situation of receiving down-votes without commenting.
The first principle is not to overreact. Note that down-votes could come from any source even from new users with low reputation and even from those who didn't get the main point of the question. Thus, all down-votes doesn't indicate that your question needs improvement!
Anyway if you feel uncomfortable about a down-vote without clear signaling, asking for an explanation is not a bad idea. Add a polite comment requesting extra explanations of the voter. It sometimes happens that your required explanation comes from another user which could guide you to the possible issue in your post.
If your question is somehow typical, reading similar questions could also help improving your post.
If these unreasonable voting without signaling happens frequently in your posts, bring the issue to the meta and if it doesn't resolve ask moderators to check the situation.
@AliTaghavi, you're very right that downvoting and removing questions without a comment is cowardly and immoral and often grossly abused.
There is nothing about mathematics that requires secrecy. MO should be about mathematics, hence up/down voting should be about mathematics and not about other issues as true or imaginary bad manners, etc. MO administration may treat those other issues but without affecting the mathematics on MO via down-votes and/or removing a question.