5. The method of claim 4 , wherein each of the one or more first nodes that correspond to a keyword in the generated graph is associated with a predefined weight corresponding to a probability of occurrence of the keyword, and each of the one or more second nodes that correspond to a keyword in the generated graph is associated with a predefined weight corresponding to a probability of occurrence of the keyword.
5. The method of claim 4 , wherein each of the one or more first nodes that correspond to a keyword in the generated graph is associated with a predefined weight corresponding to a probability of occurrence of the keyword, and each of the one or more second nodes that correspond to a keyword in the generated graph is associated with a predefined weight corresponding to a probability of occurrence of the keyword. 6. The method of claim 5 , further comprising: updating the predefined weight of each of the one or more first nodes and the predefined weight of each of the one or more second nodes in the generated graph.