Well, this is highly tangential, but if you're talking about LaTeX formatting, \epsilon is not generally what you want for the "element of" symbol. Instead, use \in. The biggest difference is that \in is a binary operator and has the appropriate spacing.

Example of the difference: http://i.imgur.com/gwAqirx.png

generated by code:

  \textbackslash{}epsilon: $\epsilon$ \\ 
  Example: $x \epsilon \mathbb{R}$
  
  \textbackslash{}in: $\in$ \\ 
  Example: $x \in \mathbb{R}$

If you use \mathbin{\epsilon} instead, you'll get proper binary operator spacing, but you'll still get odd looks from people who are accustomed to \in. Admittedly, the symbol did historically begin as an epsilon, but that notation died off a while ago.