Finally, note that we train a separate PRA model for each relation r. Path Discovery: Given a graph and a target relation r, the total number of path types is an exponential function of the maximum path length and considering all possible paths would be computationally very expensive.
b is constructed using only path types that satisfy the following two constraints: 1. the path type is active for more than K training query nodes, and 2. the probability of reaching any correct target node t is larger than a threshold α on average for the training query nodes s. We will discuss how K, α and the training queries are chosen in Section 5.