Traps and Pitfalls of Topic-Biased PageRankPaolo Boldi∗ Roberto Posenato† Massimo Santini Sebastiano Vigna Dipartimento di Scienze dell’Informazione, Università degli Studi di Milano, Italyand† Dipartimento di Informatica, Università degli Studi di Verona, ItalyAbstractWe discuss a number of issues in the definition, computation and comparison of PageRank values that have been addressed sparsely in the literature, often with contradictory approaches. We study the difference between weakly and st