Relational/SQL database technology includes logic to optimize access to the database for answering a query - query optimization. There's a classic paper by Selinger et al. Now that we have search engines and natural language interfaces are the trend, isn't there a need for new optimization logic so that the input from the user, parsed with an NLU technique like a hidden markov model, can be translated into a query execution plan? Is anyone working on this problem? Have any papers addressed it? It will be great to hear about research along these lines.