System and method for filtering rules for manipulating search results in a hierarchical search and navigation system

A method is disclosed for modifying the results of a search performed in a collection of items by a search and navigation system. The method includes receiving a query from a user interface and determining a navigation state, defined by expressions of attribute-value pairs, based on the received query. The user interface accepts both selecting and deselecting of any of the attribute-value pairs in an expression corresponding to a navigation state to obtain an expression corresponding to a different navigation state, and each selection and deselection forms a new query. The method further includes retrieving, from the collection, items associated with the navigation state to form a set of unmodified search results, the set of unmodified search results having an arrangement for presentation to the user. A rule filter that includes a metadata expression is applied to a set of rules, each rule having a trigger, an action, and metadata. The application of the rule filter to the set of rules includes evaluating the metadata expression of the rule filter based on the metadata of each rule and passing rules for which the metadata expression of the rule filter evaluates as logical true. The trigger of each rule passed by the rule filter is evaluated, and the action of each rule for which the trigger of the rule evaluates as logical true is executed to modify the unmodified search results to form modified search results.