"Is this really a proof?" is the exact question e-mailed to me today from an undergraduate mathematics student whom I know as a highly competent student. The one sentence question was accompanied with the following demo:
I am looking for a down-to-earth, non-authoritative answer who one may give to such a student. What would be your answer if you were faced with such a question?
Update. after closure Before. Reading the question gets closed , I should stresscomments you may realized that most of them answer the question wasn't (isn't) for you inoriginal title of the sense that whether you think it ispost: "Is this really a proof or not.?" Of course, the answer to such a question is as clear as the daylight for MO users. TheAnd, such a question should be closed asap. But, the actual question was (is) in the body of the post, and it was (is) what your constructive answer would be to such a student if you were faced with such a question.
Second Update "The question" at Now, with the first linechange of the first update refers to the original title: "Is this really a proof?". Now that the title has changed, the meaningactual question is much more clearer, and I hope, worthy of the first update has also changed!MO attention.