1. A method for measuring proximity of at least two nodes in a network, comprising: computing by a processor a candidate sub-graph of the network; determining at least one cycle free escape conductivity (CFEC) proximity of the at least two nodes in accordance with the candidate sub-graph, wherein the CFEC proximity is determined in accordance with a cycle free escape probability, wherein the cycle free escape probability is a probability that a random walk originating at one of the at least two nodes reaches another one of the at least two nodes without visiting any node in the network more than once; and extracting a proximity sub-graph in accordance with the at least one cycle free escape conductivity (CFEC) proximity.