Fig. 3

Overview of MCTS-RNA. Each node of the search tree has an assignment event. The search tree is gradually expanded by repeating the four steps: Selection, Expansion, Simulation and Backpropagation. In the selection step, the tree is traversed from the root node to a leaf node by taking the child node with the largest UCB-score at each branch. If necessary, children nodes are added to the leaf node in the expansion step. In the simulation step, a number of sequences are generated by local search. Finally, parameters at the ancestor nodes are updated in the backpropagation step. These four steps are repeated until a sequence with the target structure is found