1. A computing device for ranking of vertices of a directed graph, the computing device comprising: a processor; an indication of links between the vertices of the directed graph; prior knowledge relating to ranking of the vertices of the directed graph; and a component that generates a ranking of the vertices based on the links between the vertices consistent with the prior knowledge relating to ranking of the vertices the component being implemented as computer-executable instructions stored in memory of the computing device for execution by the processor wherein the ranking is based on solving the following objective functions and constraints: π ⁡ ( E ) = arg ⁢ ⁢ min π ⁢  E  F 2 + c ⁢ ⁢ π T ⁡ ( I + E - P ) ⁢ ( I + E - P ) T ⁢ π 
 s.t. e T π=1 
 π≧0 
 Aπ>Bπ and E ⁡ ( π ) = arg ⁢ ⁢ min E ⁢  E  F 2 + c ⁢ ⁢ π T ⁡ ( I + E - P ) ⁢ ( I + E - P ) T ⁢ π 
 s.t. ( P−E ) e=e 
 ( P−E )≧0.