title: Can a RegEx with negative lookahead be represented as a finite automaton?
body: <p>I'm working on a tool for manipulating context-free languages, and the internal representation of a grammar is stored as a finite automaton. Looking farther into EBNF and RegEx, I learned that EBNF has "exceptions" and RegEx has negative lookahead. I can see how these might be modeled by a symmetric difference NFA, but had suspected they are beyond the capabilities of a regular DFA or NFA.</p>
  
  <p>But then I came across <a href="http://link.springer.com/chapter/10.1007/978-3-642-31623-4_24" rel="nofollow">this</a> which pretty plainly suggests that I was wrong. Can anyone point to a free resource that might show how to convert an EBNF with exceptions, or a RegEx with negative lookahead, into a DFA?</p>