This is a guide to translating the language of math textbooks and professors.

1) It can be proven...
     This may take upwards of a year, and no shorter than four hours, and
     may require something like 5 reams of scratch paper, 100 pencils,
     or 100 refills( For those who use maechanical pencils).  If you are
     only an undergraduate, you need not bother attempting the proof as
     it will be impossible for you.
2) It can be shown...
     Usually this would take the teacher about one hour of blackboard
     work, so he/she avoids doing it.  Another possibility of course is
     that the instructor doesn't understand the proof himself/herself.
3) It is obvious...
     Only to Phd's who specialize in that field, or to instructors
     who have taught the course 100 times.
4) It is easily derived...
     Meaning that the teacher figures that even the student could derive it.
     The dedicated student who wishes to do this will waste the next weekend
     in the attempt.  Also possible that the teacher read this somewhere,
     and wants to sound like he/she really has it together.
5) It is obvious...
     Only to the Author of the textbook, or Carl Gauss.  More likely is
     only Carl Gauss.  Last time I saw this was as a step in a
     proof of Fermat's last theorem.
6) The proof is beyond the scope of this text.
     Obviously this is a plot.  The reader will never find any
     text with the proof in it.  The Proof doesn't exist.  The theorem
     just turned out to be usefull to the author.
7) The proof is left up to the reader.
     ...sure let us do all the work.  Does the author think that we have
     nothing better to do than sit around with THEIR textbook, and do the
     work that THEY should have done?
8) Sample Proof:
   .
   .
   .
   4.7  At this point we assume that x is an element of the set S, and
        therefore...We know this according to L. Krueger[pg. 71]
   Question...has anyone ever bothered to see if these type of references
   exist.  Come on...we all know what happens when we are writing a fresh-
   man english composition and run out of sources...how better to prove
   your thesis with a little blurb from some obscure, and nonexistant
   source