[deoxxa]

Yep, Prolog is pretty great for that kind of thing. I'm working on a project right now where I'm using Prolog (via tau-prolog) in the browser to determine permissible input options based on the user's existing selections. I'm also using it (via https://github.com/mndrix/golog) to apply those restrictions on the server, and to calculate the pricing for a configuration. In most cases I'm generating Prolog code from a collection of tick boxes, but for complex campaigns I can dig in and write a specific implementation of the required rules. Very flexible.