1. A method for assisting a user with a search, the method comprising: providing one or more concept networks, each concept network including a plurality of units and relationships among the units, wherein the relationships among the units are selected from a group consisting of extensions, associations and alternatives; receiving a baseline query; executing, using a processing device, a baseline search using the baseline query; transmitting, using the processing device, a result of the baseline search to the user; and in response to a user request: modifying, using the processing device, the baseline query to generate a modified query based at least in part on relationship information from at least one of the concept networks, the relationship information pertaining to at least one baseline unit extracted from the baseline query; executing a modified search using the modified query; transmitting, using the processing device, to the user a result of the modified search; and prompting, via the processing device, the user to provide feedback on the result of the modified search, wherein the user feedback is usable to perform a further modification to at least one of the baseline query and the modified query.