1. A computer-implemented method for retrieving information comprising: storing in a data structure a plurality of attribute-value pairs associated with a collection of materials, wherein each of a plurality of values has an association with at least one of a plurality of attributes characterizing the materials; providing a user interface for entering a query to retrieve information regarding the collection of materials; displaying through the user interface a first set of navigation options corresponding to a plurality of attribute-value pairs associated with a plurality of attributes; in response to a query received at the user interface that includes a selection of at least a first attribute-value pair from the first set of navigation options: displaying through the user interface a representation of a first navigation state responsive to the query, the first navigation state corresponding to a first set of attribute-value pairs and to a first particular subset of the materials, the first set of attribute-value pairs including at least the first selected attribute-value pair, the first particular subset of the materials consisting of those materials in the collection of materials that are each described by every attribute-value pair in the first set of attribute-value pairs; and displaying through the user interface a second set of context-dependent navigation options for selecting a term corresponding to an attribute-value pair so as to navigate from the first navigation state to another navigation state, the second set of context-dependent navigation options including an option to select a term corresponding to a second attribute that was not represented by the user interface in the first set of navigation options; and in response to a selection of a term corresponding to a second attribute-value pair associated with the second attribute as a navigation option from the second set of context-dependent navigation options: displaying through the user interface a representation of a second navigation state responsive to the selection of the second attribute-value pair, the second navigation state corresponding to a second set of attribute-value pairs and to a second particular subset of the materials, the second particular subset of the materials consisting of those materials in the collection of materials that are each described by every attribute-value pair in the second set of attribute-value pairs; and displaying through the user interface a third set of navigation options for navigating from the second navigation state to another navigation state, the third set of navigation options including an option to de-select a term corresponding to an attribute-value pair other than the second attribute-value pair.