From the paper: "Second, while the recommendation system algorithm we give is asymptotically exponentially faster than previous algorithms, there are several a

From the paper: "Second, while the recommendation system algorithm we give is asymptotically exponentially faster than previous algorithms, there are several aspects of this algorithm that make direct application infeasible in practice. First, the model assumptions are somewhat constrictive. It is unclear whether the algorithm still performs well when such assumptions are not satisfied. Second, the exponents and constant factors are large (mostly as a result of using Frieze, Kannan, and Vempala’s algorithm [10]). We believe that the “true” exponents are much smaller, but our technique is fairly roundabout and likely compounds exponents unnecessarily. These issues could be addressed with more straightforward analysis combined with more sophisticated techniques."