Quote:
Originally Posted by fgpancorbo
, sure, Cauchy like in "CauchySchwarz"? I don't want to sound cocky but I thought about bringing that ammunition myself except that I was unable to identify the inner product but now that I think about it... there is that cross term that looks very much like one... Interesting. Correction; I said earlier that I had the proof, but I still have to work out the details on paper. I just did it in my mind; the actual details are a bit more elaborated but I don't see a problem getting there .

OK, I finally got it
. It's a bit more technical that I originally thought. If I am allowed, I think that there is another hint needed, and that's the
http://en.wikipedia.org/wiki/Inequal...The_inequality . Professor Yaser, feel free to remove this comment if I am giving too much out. Maybe there is a easier way, but I needed both equalities,
http://en.wikipedia.org/wiki/Cauchy%...arz_inequality and
http://en.wikipedia.org/wiki/Inequal...The_inequality to prove the option for which I was unable to find a counter example.