1. A system including instructions recorded on a non-transitory computer-readable medium, and executable by at least one processor, the system comprising: a query collector configured to cause the at least one processor to receive a plurality of queries received from a user and applied by a search engine to obtain corresponding search results, the query collector including a session manager configured to identify at least one search session of the user during which the plurality of queries were received in a sequence; a graph manager configured to cause the at least one processor to generate, based on the plurality of queries, an initial graph of nodes, each node corresponding to at least one query and connected by an edge to another node in an order corresponding to the sequence, wherein the order and the sequence include at least one conflict in which a first parent node is connected by a first edge to at least one child node that is itself a second parent node connected by a second edge to the first parent node, and further configured to cause the at least one processor to merge at least two of the nodes based on a similarity of corresponding queries thereof, to obtain a merged node, the graph manager further including a conflict resolver configured to detect the at least one conflict and resolve the at least one conflict including determining that the second parent node corresponds to a higher value of at least one search quality metric than the first parent node, and then removing the second edge, based on the determining, to thereby transform the initial graph into a directed graph, and a representative query generator configured to relate the merged node with a domain topic of an ontology base and generate at least one representative query representing the merged node, based on the ontology base; and a suggestion generator configured to cause the at least one processor to match a current query with a matching node of the nodes, follow the directed graph from the matching node until the merged node is reached within the directed graph, and provide the at least one representative query to the user as a suggested query for a future search to be conducted by the search engine.