Write Texinfo documentation for grep. The manual page would be a good place to start, but Info documents are also supposed to contain a tutorial and examples. Fix the DFA matcher to never use exponential space. (Fortunately, these cases are rare.) Improve the performance of the regex backtracking matcher. This matcher is agonizingly slow, and is responsible for grep sometimes being slower than Unix grep when backreferences are used. Provide support for the Posix [= =] and [. .] constructs. This is difficult because it requires locale-dependent details of the character set and collating sequence, but Posix does not standardize any method for accessing this information!