1. A machine-implemented method comprising: analyzing digital information viewed as a labeled graph, including nodes and edges, based on a flow of authority among the nodes along the edges, the flow of authority being derived at least in part from different authority transfer rates assigned to the edges based on edge type schema information; and generating a keyword-specific ranking of the nodes in response to a query, including at least one keyword, based on a result of the analyzing; wherein the keyword-specific ranking is generated in memory by one or more computers configured to process keyword queries of the digital information comprising words; the method further comprising: receiving the query, the query including multiple keywords; wherein the analyzing the digital information comprises generating multiple initial rankings corresponding to the multiple keywords, each of the multiple initial rankings indicating authority of the nodes with respect to each respective keyword; and wherein the generating the keyword-specific ranking comprises combining the multiple initial rankings; wherein the generating the multiple initial rankings comprises topologically sorting the labeled graph, and wherein the generating the multiple initial rankings comprises identifying and removing cycles in the labeled graph to reduce the labeled graph into a directed acyclic graph (DAG) and a set of backward edges before doing keyword-specific calculation of the multiple initial rankings; identifying a set of backnodes, which are nodes of the labeled graph from which the backward edges start; and calculating node rank information in a bifurcated fashion such that calculation of the node rank information is split between (1) calculating DAG node rank information while ignoring the backward edges and (2) calculating backedges node rank information, due to the backward edges, using the identified backnodes.