blackhat blog

FROM: ecomatrix.eu

Mathematics
A simple variant of the TrustRank algorithm is given by

 TrustRank = M^(-1) *  X
where the matrix M (analogue to the PageRank algorithm) is given by
 M = 1 – d  T
with
 T_ij = 1 / C_j (if page j is linking to page i)
 T_ij = 0 (otherwise)
d is a damping factor and X the source vector of the trust.

The inverse PageRank is given by

 M_inv^(-1) * X_inv
with
 M_inv = 1 –  d_inv  T_inv
The inverse transition matrix T_inv is definied by
 T_ij = 1 /  n_j (if page i is linking to page  j)
 T_ij = 0 (otherwise)
d_inv is an additional damping factor, X_inv is the source vector of the spam (the bad pages) and n_j ist he number of incoming links on page j. M_inv is nether the transponent nor the inverse matrix of M.