The label of the node that minimizes the value of θ j,t is selected, where θ j,t is sampled from a normal distribution with a mean of s j,t and a variance of σ 2 j,t (n s j,t ) -1 . According to the probability matching method, nodes are randomly chosen from the pool of candidates according to the probability of "sampling the node with the minimum mean score." Here, adjacent nodes are expected to have relatively close scores, which is succinctly expressed through a normal distribution that decays continuously with respect to the score difference.