What algorithm is Facebook using for People You May Know that found my neighbour

[shinamee]

http://www.quora.com/What-algorithm-is-Facebook-using-for-People-You-May-Know-that-it-was-even-able-to-find-my-neighbour-2-years-ago-whom-I-had-no-connection-with?__snids__=817719422&__nsrc__=1&__filter__=all&share=1