Relating Complexity to Practical Performance in Parsing with   Wide-Coverage Unification Grammars
  The paper demonstrates that exponential complexities with respect to grammar size and input length have little impact on the performance of three unification-based parsing algorithms, using a wide-coverage grammar. The results imply that the study and optimisation of unification-based parsing must rely on empirical data until complexity theory can more accurately predict the practical behaviour of such parsers. 
John Carroll (University of Cambridge, Computer Laboratory)