Cracking the "six degrees of separation"

University of Massachusetts Amherst researchers have developed an algorithm that helps explain the sociological underpinnings of the "six degrees of separation" theory. From the press release." Participants in the Travers and Milgram study who efficiently sent the message probably acted intuitively by combining two human traits that apply to computerized network-searching as well,say the researchers. People tend to associate with people who are like themselves,and some individuals are more gregarious than others. "Searching" using both of these factors, one can efficiently get to a target even when little is known about the network’s structure. The tendency of like to associate with like,or homophily, means that attributes of a node—an individual in the Travers and Milgram study—tend to be correlated.Bostonians often know other Bostonians,and the same holds true for qualities such as age or occupation. The second important characteristic of these networks is that some people have many more acquaintances than others. This "degree disparity" leads to some individuals acting as hubs. Taking these factors into account simultaneously results in a searching algorithm that gets messages to the target by passing it to gregarious individuals who are most like the target. Or in the language of network-searching,it favors nodes that maximize the probability of linking directly to the target, which is a function of both degree and homophily,say the scientists".

Read the theory explained on the Amherst website