[plank]

Not a (former) mathematicien (but as a former PhD student in theoretical physics still some affinity with math): I remember being shocked when, having derived a result using pen and lots of sheets of paper, my co-promotor told me to just write '<expression one> can be rewritten as <expression two>' and only briefly explaining how (nothing more then a line or two), as the magazine we were to publish (and did publish) the article would not want any of those calculations written out.