Their implementation is often different from their formal representation, particularly in the ability to handle squares, which is NP-hard.
Their implementation is often different from their formal representation, particularly in the ability to handle squares, which is NP-hard. Quantification can be difficult sometimes because of greedy evaluation. A backtracking algorithm can be used to implement them, while another method transforms a nondeterministic finite automata to a deterministic finite automata. Formally equivalent to a type 3 Chomsky grammar, the notation for it was developed by Stephen Kleene and later adapted by Ken Thompson for use in QED [pron. "ked"]. Some of its conventions include using a dollar sign to find a newline, and using brackets to demarcate a character to be found. Used extensively in Perl and the Unix command grep, this is, FTP, what system of pattern matching?
Their implementation is often different from their formal representation, particularly in the ability to handle squares, which is NP-hard.
{regular expressions} (also accept {regex} or {regexp})