proof techniques

Many people have seen a copy of this tongue-in-cheek email on proof techniques that's been circulating since the 80's. It' funny because it's true, and here is a couple examples from machine learning literature

• Proof by reference to inaccessible literature, The author cites a simple corollary of a theorem to be found in a privately circulated memoir of the Slovenian Philological Society, 1883.
  
  Consider all the papers citing Vapnik's Theory of Pattern Recognition published by Nauka in 1974. That book is in Russian, and is quite hard to find. For instance it's not indexed in Summit, which includes US West Coast university libraries like Berkeley and University of Washington
  
  
• Proof by forward reference: Reference is usually to a forthcoming paper of the author, which is often not as forthcoming as at first.
  
  I came across a couple of these, which I won't mention because it's a bit embarrassing to the authors
  
  
• Proof by cumbersome notation: Best done with access to at least four alphabets and special symbols.
  
  Of course this is more a matter of habit, but I found this this paper hard to read because of the notation. It uses bold, italic, and caligraphic and fractur alphabets. And if 4 alphabets isn't enough, consult this page to see 9 different alphabets you can use