The assignment was to prove it not state it is obvious. They need to show that they know it is obvious and it is anything but obvious.Personally I feel it is okay to state "it is obvious" if in fact it is, or can easily be shown. Otherwise, it should be shown, IMHO.
Sometimes a person writing a proof fails to realize that their readers, who may not have been studying the topic as extensively as the author, simply may not be in the same mindset to find whatever it is, to be quite so obvious.
I have heard many complaints on the use of this phrase in texts over the years, and I have even quipped that when I read "it is obvious" I know I will most likely find it anything but!
I use "clearly" sometimes but I always make sure what I'm about to consider clear is sufficiently trivial for the reader to which the post is addressed to understand. When it comes to school work, I don't use it except for extremely basic stuff (why take risks).
They didn't prove any part of it. They just said it is clearly true.In addition, in mechanical proofs (like those so often encountered in introductory mathematics) that have many individual but similar cases to consider, I've often been guilty of proving the first case, and then briefly adding "the remaining cases can be checked in the same way" and ending the proof there. In my opinion one should not penalise if students do that in this particular context, no value is added to the proof by repeating the same argument N times.
My original question was a nice way to say this is bs but it got off track with everyone discussing the meaning of the word.Then obviously their grading should be zero. It is easy to see they had this coming. Clearly, if they had sketched some proof, it would have been different.
Trust me it was bs. They didn't try or felt that could get by with a cop out answer. This is a graduate class.Could you not just write "this need explanation" or why "why is this clear" or even just say to them thatyou can't write "this is obviou" you need to explain why it is obvious (i.e. give a proof)
I don't think it's too hard to do that and not be rude, you hardly need to walk up to them as say this us is bs you don't know what your talking about